Objective To evaluate the safety and efficacy of a self-developed micro-normothermic machine perfusion (NMP) system (micro-perfusion device) for preserving isolated porcine limbs. Methods Five healthy Landrace pigs were selected, and their left and right forelimbs were randomly divided into the NMP group and static cold storage (SCS) group. The NMP group was perfused with the self-developed micro-perfusion device and polymerized hemoglobin perfusate for 32 hours at normothermia, while the SCS group was preserved at 4 ℃. Hemodynamic parameters such as perfusion pressure and flow were monitored. The pH value, partial pressure of oxygen (PO₂), lactic acid (Lac), creatine kinase (CK) and lactate dehydrogenase (LDH) in the perfusate were measured. Hematoxylin-eosin staining was used to assess the muscle tissue structure, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was employed to evaluate muscle cell apoptosis, and immunohistochemistry staining was applied to detect the expressions of tumor necrosis factor (TNF)-α and interleukin (IL)-6. A mixed-effects model was used to analyze the effects of time and treatment methods on tissue structure, cell apoptosis and inflammatory factors. Results The device could stably maintain a perfusion pressure of (69±15) mmHg and a flow rate of (117±42) mL/min. The pH value and electrolytes of the perfusate were generally stable, with PO₂ maintained at a high level. Lac was maintained at 5.38(3.81, 6.45) mmol/L, while CK and LDH increased over time. After 32 hours of perfusion in the NMP group, both the myocyte spacing and apoptosis rate were better than those in the SCS group. Mixed-effects model analysis showed that there were statistically significant differences in the effects of NMP treatment and SCS treatment on myocyte spacing and apoptosis rate per unit time (both P < 0.05). There were no statistically significant differences in TNF-α and IL-6 between the two groups, and mixed-effects model analysis showed no statistically significant differences in the effects of NMP treatment and SCS treatment on TNF-α and IL-6 per unit time (both P > 0.05). Conclusions The micro-perfusion device used in this study may achieve 32-hour normothermic preservation in a porcine limb amputation model, maintain basic metabolism and ionic homeostasis, reduce muscle structural damage and cell apoptosis without inducing additional inflammatory responses. This technology is expected to significantly extend the time window for replantation of amputated limbs in disaster rescue and long-distance transportation, providing an important technical basis for clinical translation and subsequent replantation research.

Objective To explore the protective effects of genetically modified porcine erythrocyte suspension as a subnormothermic normoxic mechanical perfusate on hypoxic-ischemic brain injury in cynomolgus monkeys caused by traumatic hemorrhage.Methods Cynomolgus monkeys were randomly divided into positive and negative control groups(a total of 3 monkeys,with 3 left cerebral hemispheres as the positive control group and 3 right cerebral hemispheres as the negative control group)and the subnormothermic perfusion group(n=3).The positive control group was directly sampled 1 hour after circulatory arrest,while the negative control group was placed at subnormothermic conditions for 6 hours after circulatory arrest.The subnormothermic perfusion group underwent 6 hours of subnormothermic normoxic mechanical perfusion of the bilateral common carotid arteries of the cynomolgus monkey hypoxic-ischemic brain injury model using genetically modified porcine erythrocyte suspension 1 hour after circulatory arrest.Before perfusion,cross-matching experiments were conducted between the six genetically modified pig and the cynomolgus monkeys.After the start of perfusion,the levels of routine blood indicators in the perfusate were detected at 0,1,2,3,4,5 and 6 hours.Blood oxygen saturation was recorded,and the levels of Na+,K+,Ca2+,glucose and blood pH in the perfusate were measured,as well as the levels of IgG and IgM in the perfusate.After 6 hours of perfusion,the water content of the brain tissue was measured.Nissl staining was performed on the frontal cortex and hippocampal regions,and immunofluorescence staining was used to detect the expression of glial fibrillary acidic protein(GFAP),ionized calcium-binding adapter molecule 1(Iba1)and neuronal nuclear antigen(NEUN).Results The cross-matching results between the six genetically modified pig and the cynomolgus monkeys were negative.The number of red blood cells in the perfusate decreased significantly at 3 hours of perfusion,and the hemoglobin level showed a downward trend at 1,3,5 and 6 hours.The number of white blood cells and platelets decreased at all time points.The blood oxygen saturation in the subnormothermic perfusion group remained stable at 95%-98%,and the levels of blood oxygen saturation,Na+,Ca2+,glucose and pH were stable,while the K+level first increased and then decreased.There was no significant difference in the levels of IgG and IgM before and after perfusion.The water content of brain tissue at the end of perfusion in the subnormothermic perfusion group was significantly higher than that in the positive control group(P<0.001).Nissl staining results showed that compared with the positive control group,the pyramidal neurons in the prefrontal cortex of the subnormothermic perfusion group maintained better morphological integrity,with no significant increase in enlarged and deformed cells.In the hippocampal CA1 region,there was a slight increase in enlarged and deformed cells,and a few cells with undamaged structures showed reduced cell size.In the hippocampal dentate gyrus,fewer granule neurons had compromised structural integrity,with increased cell edema.NEUN immunofluorescence staining showed that compared with the positive control group,the pyramidal neurons in the prefrontal cortex and hippocampal CA1 region of the subnormothermic perfusion group had better morphological states,with clear axons.The granule cells in the hippocampal dentate gyrus were well preserved,but the nuclei were less well protected.GFAP immunofluorescence staining showed that compared with the positive control group,the subnormothermic perfusion group had sparser protrusions that were more tightly associated with neurons.Iba1 immunofluorescence staining showed that compared with the positive control group,the subnormothermic perfusion group had thicker and fewer protrusions.Conclusions Compared with the positive control group,subnormothermic normoxic mechanical perfusion with genetically modified porcine erythrocyte perfusate increases brain tissue edema in cynomolgus monkeys,but better preserves the morphological integrity of neurons and glial cells.The protective effects may be related to the continuous oxygen and energy supply,maintenance of ion homeostasis and perfusate pH,reduced rejection,and low metabolic state of the whole brain.

Objective:To explore the effects of medication interval on the quality of split-dose bowel preparation and analyze the independent risk factors affecting the quality of bowel preparation.Methods:This pilot study involved two centers. Adult outpatients who underwent screening, surveillance, and diagnostic colonoscopy in the First Affiliated Hospital of Naval Medical University ( n=46) and the Fifth Hospital of Zhangjiakou ( n=20) between April and June 2023 were enrolled. Bowel preparation was conducted based on the guideline. Patients were divided into the short-interval group (4-<10 hours, n=45) and the long-interval group (10-16 hours, n=21) based on the time between the two administrations of polyethylene glycol during bowel preparation. Differences in terms of patient-reported outcome measurements (patient-reported willingness to repeat the bowel preparation regimen, satisfaction with bowel preparation, satisfaction with sleep), defecation frequency, Boston bowel preparation scale scores, bowel preparation bubble scores, bowel preparation qualified rates, polyp detection rates and incidence of adverse events were compared. Relevant factors influencing bowel preparation quality were analyzed by univariate logistic regression. Results:There were no significant differences in patient-reported willingness to repeat the bowel preparation regimen [88.9% (40/45) VS 85.7% (18/21), χ2<0.001, P>0.999], the satisfaction with bowel preparation [65.9% (29/45) VS 57.1% (12/21), χ2=0.469, P=0.493], or the satisfaction with sleep quality [35.6% (16/45) VS 28.6% (6/21), χ2=0.314, P=0.575] between the short-interval and long-interval groups. Similarly, no significant differences were observed between the groups in defecation frequency (11.3±4.8 VS 10.2±4.4, t=0.861, P=0.395), Boston bowel preparation scale scores (8.2±1.4 scores VS 7.9±1.2 scores, t=1.024, P=0.311), bowel preparation bubble scores (8.6±1.0 scores VS 8.4±1.5 scores, t=0.672, P=0.506), bowel preparation qualified rates [88.9% (40/45) VS 90.5% (19/21), χ2<0.001, P>0.999], polyp detection rates [33.3% (15/45) VS 47.6% (10/21), χ2=1.242, P=0.265], or incidence of adverse events [24.4% (11/45) VS 14.3% (3/21), χ2=0.381, P=0.537]. Univariate logistic analysis suggested that a low-fiber diet ( OR=8.100, 95% CI:1.400-46.849, P=0.019) was an influencing factor for qualified bowel preparation. Conclusion:Medication interval of the two doses of polyethylene glycol in a split-dose bowel preparation regimen for colonoscopy has no significant impact on bowel preparation quality. Notably, preoperative low-fiber diet emerges as an independent protective factor for qualified bowel preparation.

Objective:To investigate the clinical efficacy of strengthening the spleen to nourish the lung in treating stable chronic obstructive pulmonary disease (COPD) with lung and spleen qi deficiency complicated by sarcopenia. Methods:This study was designed as a prospective study. A total of 65 patients with stable COPD and sarcopenia who received treatment at Kunshan Hospital of Chinese Medicine from January 2021 to December 2021 were included in the study. They were randomly divided into a control group and an observation group using the random number table method. The control group ( n = 34) was treated with conventional therapy, while the observation group ( n = 31) was treated with Shenling Baizhu Powder, a traditional Chinese medication based on the principle of strengthening the spleen to nourish the lung, in addition to the conventional therapy given to the control group. Both groups were treated for 1 month. Traditional Chinese medicine syndrome score, pulmonary function, grip strength, walking speed, albumin and prealbumin levels were compared between the two groups. Results:After treatment, the scores of all traditional Chinese medicine syndromes in the observation group were significantly lower than those in the control group (all P < 0.05). Compared with the control group, the levels of forced expiratory volume in the first second (FEV 1)[(1.51 ± 0.27) L vs. (1.32 ± 0.20) L, t = 3.11, P < 0.001 ] and FEV 1/forced vital capacity (FVC) [(57.20 ± 8.41)% vs. (52.89 ± 5.66)%, t = 2.30, P = 0.025] were significantly higher in the observation group. Compared with before treatment, gait speed [(1.07 ± 0.27) m/s vs. (0.90 ± 0.30) m/s, t = 7.66, P < 0.001], grip strength [(20.62 ± 5.07) kg vs. (19.42 ± 5.78) kg, t = 3.55, P < 0.001], albumin [(231.38 ± 49.40) g/L vs. (200.26 ± 65.87) g/L, t = 3.70, P < 0.001] and prealbumin [(39.53 ± 3.45) g/L vs. (35.81 ± 4.46) g/L, t = 4.08, P < 0.001] levels in the observation group were significantly increased after treatment. There were no significant differences in gait speed, grip strength, albumin, and prealbumin levels in the control group before and after treatment (all P > 0.05). Conclusions:The method of strengthening the spleen to nourish the lung shows good clinical efficacy in treating stable COPD with lung and spleen deficiency complicated by sarcopenia, and it has great potential for broader application.

Objective To analyze the clinical significance of ductoscopy,mammography,and high-frequency color Doppler ultrasonography in diagnosis of nipple bloody discharge combined with intraductal space occupying lesions.Methods The medical records of 198 patients with nipple bloody discharge combined with intraductal space occupying lesions who underwent surgical treatment from January 2023 to December 2023 were retrospectively analyzed,all the subjects were examined by ductoscopy,mammography and high-frequency color Doppler ultrasonography before operation.The results of postoperative pathology were used as the gold standard to compare and evaluate the efficacy of single and combined use of the above three methods in the diagnosis of nipple bloody discharge combined with intraductal space occupying lesions.Results The results of postoperative pathological diagnosis showed that 152 cases of intraductal benign lesions were intraductal papilloma of the breast.There were 46 malignant lesions,of which 25 were intraductal carcinoma and 21 were invasive ductal carcinoma.The detection rates of nipple bloody discharge combined with intraductal space occupying lesions were 95.45%,81.31%,84.85%and 97.47%,respectively,by ductoscopy,mammography,high-frequency color Doppler ultrasonography and combined examination.Among them,the detection rate of ductoscopy and combined examination were significantly higher than that of mammography and high-frequency color Doppler ultrasonography(P<0.05),there was no significant difference between the detection rate of ductoscopy and combined examination(P>0.05),and there was no significant difference between the detection rate of mammography and high-frequency color Doppler ultrasonography(P>0.05).The sensitivity,specificity,and accuracy of diagnosing nipple bloody discharge combined with intraductal space occupying lesions using ductoscopy were 91.30%,97.20%,and 95.77%,respectively.The above indicators of mammography were 65.00%,94.21%,and 86.96%,respectively.The above indicators of high-frequency color Doppler ultrasonography were 70.73%,96.06%,and 89.88%,respectively.The above indicators of combination of the three methods were 95.65%,97.28%,and 96.89%,respectively.The sensitivity and accuracy of the combined examination of the three methods and the use of ductoscopy alone for the diagnosis of nipple bloody discharge combined with intraductal space occupying lesions were significantly higher than those of mammography and high-frequency color Doppler ultrasonography(P<0.05).However,there was no significant difference between mammography and high-frequency color Doppler ultrasonography(P>0.05),and there was also no significant difference between the combined examination of the three methods and the use of ductoscopy alone(P>0.05).There was no significant difference in diagnostic specificity among the four groups(P>0.05).Conclusion The diagnostic sensitivity and accuracy of ductoscopy for nipple bloody discharge combined with intraductal space occupying lesions are significantly higher than those of mammography and high-frequency color Doppler ultrasonography.The combined examination of the three can improve diagnostic efficiency to a certain extent,but the effect is limited.

Objective:To explore the effects of medication interval on the quality of split-dose bowel preparation and analyze the independent risk factors affecting the quality of bowel preparation.Methods:This pilot study involved two centers. Adult outpatients who underwent screening, surveillance, and diagnostic colonoscopy in the First Affiliated Hospital of Naval Medical University ( n=46) and the Fifth Hospital of Zhangjiakou ( n=20) between April and June 2023 were enrolled. Bowel preparation was conducted based on the guideline. Patients were divided into the short-interval group (4-<10 hours, n=45) and the long-interval group (10-16 hours, n=21) based on the time between the two administrations of polyethylene glycol during bowel preparation. Differences in terms of patient-reported outcome measurements (patient-reported willingness to repeat the bowel preparation regimen, satisfaction with bowel preparation, satisfaction with sleep), defecation frequency, Boston bowel preparation scale scores, bowel preparation bubble scores, bowel preparation qualified rates, polyp detection rates and incidence of adverse events were compared. Relevant factors influencing bowel preparation quality were analyzed by univariate logistic regression. Results:There were no significant differences in patient-reported willingness to repeat the bowel preparation regimen [88.9% (40/45) VS 85.7% (18/21), χ2<0.001, P>0.999], the satisfaction with bowel preparation [65.9% (29/45) VS 57.1% (12/21), χ2=0.469, P=0.493], or the satisfaction with sleep quality [35.6% (16/45) VS 28.6% (6/21), χ2=0.314, P=0.575] between the short-interval and long-interval groups. Similarly, no significant differences were observed between the groups in defecation frequency (11.3±4.8 VS 10.2±4.4, t=0.861, P=0.395), Boston bowel preparation scale scores (8.2±1.4 scores VS 7.9±1.2 scores, t=1.024, P=0.311), bowel preparation bubble scores (8.6±1.0 scores VS 8.4±1.5 scores, t=0.672, P=0.506), bowel preparation qualified rates [88.9% (40/45) VS 90.5% (19/21), χ2<0.001, P>0.999], polyp detection rates [33.3% (15/45) VS 47.6% (10/21), χ2=1.242, P=0.265], or incidence of adverse events [24.4% (11/45) VS 14.3% (3/21), χ2=0.381, P=0.537]. Univariate logistic analysis suggested that a low-fiber diet ( OR=8.100, 95% CI:1.400-46.849, P=0.019) was an influencing factor for qualified bowel preparation. Conclusion:Medication interval of the two doses of polyethylene glycol in a split-dose bowel preparation regimen for colonoscopy has no significant impact on bowel preparation quality. Notably, preoperative low-fiber diet emerges as an independent protective factor for qualified bowel preparation.

Objective:To explore the efficacy and safety of one-hole split endoscope (OSE) minimally invasive surgery for the treatment of single-segment thoracic ossification of the ligamentum flavum (TOLF).Methods:This retrospective non-randomized controlled study included 41 patients with single-segment TOLF who underwent surgery at Qilu Hospital of Shandong University between July 2019 and July 2023. Patients were divided into two groups: the OSE group (19 cases) treated with one-hole split endoscope minimally invasive surgery and the open group (22 cases) treated with traditional laminectomy and pedicle screw fixation. There were no significant differences between the two groups on gender, age, disease duration, affected segment, presence or absence of dural ossification, and residual cross-sectional vertebral canal area on CT ( P>0.05). Additionally, perioperative surgical time, estimated blood loss (EBL), incision length, hospital stay duration, hospitalization costs and follow-up duration were compared. The Japanese Orthopaedic Association (JOA) score and Oswestry Disability Index (ODI) were compared preoperatively and at the last follow-up. Complications were also recorded. Results:All patients successfully completed the surgery with no significant differences at the last follow-up ( P>0.05). Compared with the open group, the OSE group had a significantly shorter operative time (133.1±16.8 vs. 160.5±22.6 min), lower EBL (91.2±15.0 vs. 192.5±43.8 ml), shorter incision length (2.6±0.5 vs. 7.9±1.9 cm), reduced hospital stay (3.9±0.8 vs. 5.6±0.8 days), and lower hospitalization costs (34,874.9±4,568.6 vs. 53,162.3±9,815.6 yuan) (all P<0.05). AAt the final follow-up, JOA scores (8.5±0.8 vs. 8.6±1.2) and ODI values (16.7%±2.1% vs. 17.7%±4.4%) showed no significant differences between the OSE and open groups ( P>0.05). During the perioperative period and follow-up, complications occurred in 2 patients in the OSE group (1 cerebrospinal fluid leak, 1 poor wound healing) and in 8 patients in the open group (5 cerebrospinal fluid leaks, 1 neurological deterioration, 2 poor wound healing). Conclusion:OSE minimally invasive surgery is an effective treatment for single-segment thoracic ossification of the ligamentum flavum. Compared with open surgery, it provides advantages such as minimal invasiveness and fewer complications.

Objective:To explore the efficacy and safety of one-hole split endoscope (OSE) minimally invasive surgery for the treatment of single-segment thoracic ossification of the ligamentum flavum (TOLF).Methods:This retrospective non-randomized controlled study included 41 patients with single-segment TOLF who underwent surgery at Qilu Hospital of Shandong University between July 2019 and July 2023. Patients were divided into two groups: the OSE group (19 cases) treated with one-hole split endoscope minimally invasive surgery and the open group (22 cases) treated with traditional laminectomy and pedicle screw fixation. There were no significant differences between the two groups on gender, age, disease duration, affected segment, presence or absence of dural ossification, and residual cross-sectional vertebral canal area on CT ( P>0.05). Additionally, perioperative surgical time, estimated blood loss (EBL), incision length, hospital stay duration, hospitalization costs and follow-up duration were compared. The Japanese Orthopaedic Association (JOA) score and Oswestry Disability Index (ODI) were compared preoperatively and at the last follow-up. Complications were also recorded. Results:All patients successfully completed the surgery with no significant differences at the last follow-up ( P>0.05). Compared with the open group, the OSE group had a significantly shorter operative time (133.1±16.8 vs. 160.5±22.6 min), lower EBL (91.2±15.0 vs. 192.5±43.8 ml), shorter incision length (2.6±0.5 vs. 7.9±1.9 cm), reduced hospital stay (3.9±0.8 vs. 5.6±0.8 days), and lower hospitalization costs (34,874.9±4,568.6 vs. 53,162.3±9,815.6 yuan) (all P<0.05). AAt the final follow-up, JOA scores (8.5±0.8 vs. 8.6±1.2) and ODI values (16.7%±2.1% vs. 17.7%±4.4%) showed no significant differences between the OSE and open groups ( P>0.05). During the perioperative period and follow-up, complications occurred in 2 patients in the OSE group (1 cerebrospinal fluid leak, 1 poor wound healing) and in 8 patients in the open group (5 cerebrospinal fluid leaks, 1 neurological deterioration, 2 poor wound healing). Conclusion:OSE minimally invasive surgery is an effective treatment for single-segment thoracic ossification of the ligamentum flavum. Compared with open surgery, it provides advantages such as minimal invasiveness and fewer complications.

Objective:To develop a convolutional neural network model of whole slide imaging of cerebrospinal fluid cells for rapid and accurate identification and classification of tumor cells in cerebrospinal fluid.Methods:A total of 8 692 cerebrospinal fluid cytology smears from Huashan Hospital Affiliated to Fudan University from January 2nd, 2019, to December 27th, 2024. As randomly assigned, the training set included 4 941 benign and 1 745 malignant samples, while the validation set comprised of 1 368 benign and 638 malignant samples. Whole-slide digital images were acquired using a cytopathology scanner, cells (clusters) were annotated for classification, and a deep learning model was constructed via tiled image patches for cell detection and classification. Model performance was evaluated using accuracy, sensitivity, specificity, and other indicators. The classification efficiency of manual microscopy was compared.Results:The model achieved a mean precision of 96.75% for cerebrospinal fluid cell classification. For malignant tumor cells, the classification accuracy was 96.61% (mAP=98.36%, AUC=0.97). Subtype classification accuracies for epithelial/epithelioid tumors and small round cell tumors were 97.13% (AUC=0.98) and 95.58% (AUC=0.93), respectively. Compared with manual microscopy, which took (9.70±0.82) minutes for classifying 200 cells, (18.27±1.21) minutes for 500 cells, and often exceeded 60 minutes or infeasible for full slides, the AI model took (3.46±0.49) seconds for 200 cells, (6.76±0.82) seconds for 500 cells, and a median of 48.57 seconds for full slides ( P<0.001), representing an efficiency improvement of approximately 161-170 times, significantly enhancing diagnostic efficiency. Conclusion:This fully automated hierarchical deep learning model enables efficient and accurate tumor cell identification and classification in CSF, providing an effective auxiliary tool for the rapid diagnosis of meningeal carcinomatosis.

Objective To explore the mechanism of Lidan Huatan Huoxue Decoction improving cognitive impairment caused by obesity based on metabolomics.Methods Twenty-four 6-week-old male SD rats were randomly divided into a normal group fed with regular diet(Con,n=6)and a modeling group fed with high-fat and high-sugar diet(n=18).Rats with a body mass that is 20%higher than the standard body mass of their age-matched peers fed with ordinary diet were considered to have a successful obese model established.The presence of cognitive impairment was assessed by Morris water maze and Barnes maze tests.After the obese-induced cognitive impairment(OICI)model was established,the modeling rats were randomly divided into a model group(Model,n=6),a donepezil group(Donepezil,n=6),and a Lidan Huatan Huoxue Decoction group(LHH,n=6).Drugs were administered to the donepezil and LHH groups by gastric intubation.The donepezil group was administered with a dose of 0.45 mg·(kg·d)-1,while the LHH group was administered with a dose of 25 g·(kg·d)-1.The normal and model groups were given the same volume of normal saline by gastric intubation for 8 weeks.Before the rats were sacrificed,water maze and Barnes maze experiments were conducted to assess cognitive function.After sacrifice,specimens were collected for biochemical and histological examination of liver tissue and brain tissue.Non-targeted metabolomic analysis using liquid chromatography-mass spectrometry(LC-MS)was performed on feces,serum,and brain tissue to analyze changes in differential metabolites in rats.Results Compared with the model group,the intervention of Donepezil and LHH effectively improved the learning and memory ability of OICI rats(P<0.05 or P<0.01),inhibited the overactivation of hippocampal microglia,and increased the number of hippocampal synaptic proteins.LHH improved metabolic-related indicators in OICI rats(P<0.05 or P<0.01).Metabolomic analysis showed significant differences in metabolites in feces,serum,and brain tissue between the model group and the normal group.The main affected pathways in fecal metabolites included steroid biosynthesis,caffeine metabolism,lysosome,vitamin B6 metabolism,phenylalanine,tyrosine,and tryptophan biosynthesis.The main affected pathways in serum metabolites included central carbon metabolism in cancer,pentose phosphate pathway,mineral absorption,protein digestion and absorption,and aminoacyl-tRNA biosynthesis.The main affected pathways in brain tissue metabolites included glycerophospholipid metabolism,β-alanine metabolism,propionic acid metabolism,niacin and nicotinamide metabolism,and caffeine metabolism.After LHH intervention,fecal metabolites showed the most significant changes,mainly involving vitamin B6 metabolism,vitamin digestion and absorption,histidine metabolism,fructose and mannose metabolism,and steroid biosynthesis.Conclusion LHH can improve cognitive impairment in obese rats mainly by regulating fecal metabolites.The main pathways involved include vitamin B6 metabolism,vitamin digestion and absorption,histidine metabolism,fructose and mannose metabolism,and steroid biosynthesis.Among them,vitamin B6 metabolism and vitamin digestion and absorption may be the most important pathways.