Antrodia cinnamomea reduces obesity and modulates the gut microbiota in high-fat diet-fed mice.

BACKGROUND: Obesity is associated with gut microbiota dysbiosis, disrupted intestinal barrier and chronic inflammation. Given the high and increasing prevalence of obesity worldwide, anti-obesity treatments that are safe, effective and widely available would be beneficial. We examined whether the medicinal mushroom Antrodia cinnamomea may reduce obesity in mice fed with a high-fat diet (HFD). METHODS: Male C57BL/6J mice were fed a HFD for 8 weeks to induce obesity and chronic inflammation. The mice were treated with a water extract of A. cinnamomea (WEAC), and body weight, fat accumulation, inflammation markers, insulin sensitivity and the gut microbiota were monitored. RESULTS: After 8 weeks, the mean body weight of HFD-fed mice was 39.8±1.2 g compared with 35.8±1.3 g for the HFD+1% WEAC group, corresponding to a reduction of 4 g or 10% of body weight (P<0.0001). WEAC supplementation reduced fat accumulation and serum triglycerides in a statistically significant manner in HFD-fed mice. WEAC also reversed the effects of HFD on inflammation markers (interleukin-1ß, interleukin-6, tumor necrosis factor-α), insulin resistance and adipokine production (leptin and adiponectin). Notably, WEAC increased the expression of intestinal tight junctions (zonula occludens-1 and occludin) and antimicrobial proteins (Reg3g and lysozyme C) in the small intestine, leading to reduced blood endotoxemia. Finally, WEAC modulated the composition of the gut microbiota, reducing the Firmicutes/Bacteroidetes ratio and increasing the level of Akkermansia muciniphila and other bacterial species associated with anti-inflammatory properties. CONCLUSIONS: Supplementation with A. cinnamomea produces anti-obesogenic, anti-inflammatory and antidiabetic effects in HFD-fed mice by maintaining intestinal integrity and modulating the gut microbiota.

[Expression and intratumoral heterogeneity of LN-5γ2 in esophageal squamous cell carcinoma].

OBJECTIVE: The present study aimed to evaluate the expression and intratumoral heterogeneity of LN-5γ2 in esophageal squamous cell carcinoma (ESCC). METHODS: The expression of LN-5γ2 protein was examined in 135 ESCC cases by immunohistochemistry, and to analyze its relationship with the clinical relevance of patients. The protein expressions in different regions in the same tumor as well as different nests in the same region were compared. RESULTS: Moderate and high expression of LN-5γ2 protein was detected in 40.0% (54/135) of tumor tissues. Positive immunohistochemical staining was observed in 31.1% (23/74) of early stage (stages Ⅰ/Ⅱ) cases and 50.8% (31/61) of late stage (stage Ⅲ) cases, with a significant difference between these two groups (P=0.023). There was no statistical association of LN-5γ2 expression with age, sex of patients, PT sage, lymph node metastasis and degree of tumor differentiation (P>0.05). However, differential expression of LN-5γ2 protein was found at different sampling sites in the same tumor and the same sampling site in different carcinomas. CONCLUSION: High expression of LN-5γ2 is positively correlated with tumor clinical stages and there existed intratumoral heterogeneity of LN-5γ2 expression in ESCC tissues.

Smoking behaviours of adolescents, influenced by smoking of teachers, family and friends.

BACKGROUND: Smoking tobacco is a global health problem, and this study highlights adolescent smoking in Taiwan. Smoking was completely banned on campuses under the Tobacco Hazards Prevention Act and School Health Regulations. Few have investigated the association between personnel smoking/school smoking policies and adolescent smoking in Taiwan. The smoking rate has gradually increased for senior high school students in Taiwan from 10.7% in 1994 to 14.7% in 2011. AIM: This study examined the influence of family and friends' smoking on the association between the presence of teachers smoking and each stage of adolescents' smoking behaviour. METHODS: A cross-sectional survey was conducted in nine high schools (n = 921). Logistic regression analysis was used to examine the association between smoking stage, father smoking, mother smoking, sibling smoking, friends smoking and the presence of smoking teachers. RESULTS: After adjusting for gender, school type and grade, fathers', siblings' and friends' smoking were significantly associated with adolescents' ever and current smoking behaviours, but mothers' smoking was only associated with adolescents' current smoking behaviours. Friends' smoking was strongly associated with being a smoker. While there was an interaction between friends' smoking and the presence of smoking teachers on current smoking behaviours indicating the effect of the presence of smoking teachers was increased when friends did not smoke. DISCUSSION: The results suggest that teachers smoking on school may increase the likelihood of being a current smoker as their friends do not smoke. Family and friends smoking are associated with adolescent smoking. CONCLUSION: The Taiwanese government has regulated a comprehensive smoking ban in schools to prohibit both student and staff smoking on all school premises. To achieve this, schools should make tobacco control communication efforts. Nurses could address the combined influence of family and friends as well as the effect of school smoking restrictions to help prevent adolescents from smoking.

The effect of pre-procedure anxiety on sedative requirements for sedation during colonoscopy.

This study investigated the effects of pre-procedural anxiety (assessed using the Beck Anxiety Inventory) on sedative requirements in 135 patients undergoing sedation for colonoscopy. Deep sedation was defined as loss of consciousness and no response to colonoscopy, and was achieved by target-controlled infusion of propofol. Patients' characteristics, baseline haemodynamic profiles, Beck Anxiety Inventory scores, effect-site propofol concentration at loss of consciousness and characteristics of recovery were recorded. No correlations were found between Beck Anxiety Inventory scores and effect-site propofol concentration at loss of consciousness or baseline haemodynamic profiles. There was no statistical difference in the characteristics of recovery among patients with different levels of anxiety. In conclusion, in patients receiving deep sedation for colonoscopies, the level of pre-procedural anxiety did not relate to the sedative requirement or post-procedural recovery characteristics.

Comparison of clinical outcome of single-incision laparoscopic surgery using a simplified access system with conventional laparoscopic surgery for malignant colorectal disease.

AIM: Instrument crowding is encountered in single-incision laparoscopic surgery (SILS). Our aim was to compare the results of SILS with those of conventional laparoscopic surgery (CLS) for malignant colorectal disease. METHODS: The records of 27 patients who received SILS for the treatment of malignant disease using a home-made multiple-port system were compared with those of 68 patients who received CLS performed in a standard manner using four to five trocar sites. RESULTS: There were no significant differences in age, gender, disease stage, tumour location or tumour size between the SILS and CLS groups. The most common surgery was high anterior resection in both groups (SILS, 63.0%vs CLS, 58.8%). There were no significant differences between the groups in types of surgery performed, length of bowel resected, resection margin, blood loss, duration of surgery or postoperative complications. Postoperative pain scores were significantly higher in the SILS group than in the CLS group (3.07 ± 1.14 vs 2.41 ± 0.63, respectively, P < 0.001). CONCLUSIONS: SILS is as effective as CLS, and is not associated with increased duration of surgery, blood loss or complications.

Carotid intima-media thickness in Chinese Type 2 diabetic subjects with or without microalbuminuria.

BACKGROUND: To examine the association of microalbuminuria (MAU) with the carotid intima-media thickness (CIMT) in Chinese Type 2 diabetic subjects. MATERIALS AND METHODS: Two hundred and thirty-nine patients (64±13 yr, 154 males) were divided into 2 groups: one with MAU (no.=119) or one without (no.=120). We recorded clinical and biochemical data as well as CIMT and ankle-brachial index (ABI). RESULTS: The patients with MAU had had diabetes mellitus (DM) longer, had higher blood pressure (BP). They also had lower estimated glomerular filtration rate (eGFR) and higher levels of circulating glucose, glycated hemoglobin, high sensitivity C-reactive protein than those without. Lower mean ABI was found in those with MAU, however, they did not have higher mean CIMT (0.72±0.15 vs 0.71±0.16 mm, p=0.525). In patients without MAU, CIMT correlated with age, DM duration, systolic BP, eGFR, albumin- to-creatinine ratio, and ABI. However, in those with MAU, CIMT correlated only with age and eGFR. Multivariate regression analysis revealed that mean CIMT correlated only with age for patients without MAU, but correlated with age and body mass index for those with MAU. Dividing the patients into 5 age groups, we found that the older the patient, the higher the mean CIMT with no group differences between those with and without MAU in both genders. However, patients with eGFR below 60 ml/min/1.73 m(2) had higher mean CIMT than those above (0.75±0.16 vs 0.69±0.14 mm, p=0.005). CONCLUSIONS: Type 2 diabetic patients with MAU were not associated with higher CIMT. Conversely, those with deterioration of renal function were more likely associated.

Right- and left-subclavian vein port-a-cath systems: comparison of complications.

BACKGROUND: Central venous access systems are frequently used for delivery of medications; however, few studies have compared surgical and postoperative complications of right versus left access via the subclavian vein (SCV). The aim of this study was to compare the surgical and postoperative complications associated with Port-A-Cath system insertion via the right and left SCV. METHODS: The medical records of patients who received Port-A-Cath insertion via the SCV for parenteral chemotherapy between August 2004 and July 2008 were reviewed. The incidence of surgical and postoperative complications was compared between patients who received right- versus left-SCV Port-A-Cath insertion. RESULTS: A total of 1,848 patients were included in the study. Right-SCV catheterization was attempted in 1,029 (55.7%) patients and was successful in 866 (84.2%). Left-SCV catheterization was attempted in 819 (44.3%) patients and was successful in 651 (79.5%). The mean length of postoperative follow-up was 417.3 ± 401.3 and 396.7 ± 379.9 days for the right- and left-SCV groups, respectively. The incidence of SCV puncture failure was significantly lower in the right-SCV group (12.3%) compared with the left-SCV group (16.8%, p = 0.006). The incidence of catheter knotting at the ipsilateral brachiocephalic vein was also significantly lower in the right-SCV group (0.0%) compared with the left-SCV group (0.5%, p = 0.038), as was the incidence of catheter occlusion (1.0% for right SCV vs. 3.5% for left SCV, p = 0.001). CONCLUSION: These findings suggest that the right-SCV approach is superior to the left-SCV approach for Port-A-Cath insertion.

Effects of sebum on drug transport across the human stratum corneum in vivo.

The objective of this study was to investigate the effect of sebum on drug transport across the human stratum corneum (SC) in vivo for two model compounds, 4-cyanophenol (CP) and cimetidine (CM), of different lipophilicity and molecular size by utilizing noninvasive tape-stripping techniques, in conjunction with an unsteady-state diffusion model for data analysis. The results demonstrated that the SC permeability of the relatively hydrophilic CM on the forehead may be as much as four times the permeability on the forearm. The administration of sebum supplementation to the forearm increased the SC permeability of CM more than threefold, but did not have the same effect with regard to CP. Removal of sebum from the forehead demonstrated a small but significant effect (-22%) on the SC permeability of CM. The presence of sebum on the forehead or forearm increased the diffusion of both molecules, but the effect on partition varied between sites and drugs. The change in the SC permeability of the relatively hydrophilic drug using sebum treatment may be attributable to the altered barrier function of the SC due to the disordering structures of the intercellular lipid molecules.

Involvement of the cyclic-AMP-dependent protein kinase A pathway in thyroxine effects on calcitonin secretion from TT cells.

Previous studies have demonstrated that plasma calcitonin is lower in hypothyroid patients and that thyroxine stimulates the human thyroid to release calcitonin. Therefore, thyroid hormones may regulate the secretion of calcitonin, but further work is needed to address this possibility in more detail. TT cells, a model of human thyroid C cells, were incubated in a medium containing vehicle, thyroxine, or thyroxine methyl-hemisuccinate-bovine serum albumin (BSA-L-T(4), thyroxine was immobilized and linked to BSA); then, the levels of secreted calcitonin (hCT), calcitonin mRNA, and cAMP were measured. To study links that connect the cAMP-dependent protein kinase A (PKA) pathway to the observed thyroxine effects, cells were treated with either vehicle or thyroxine plus SQ22536 [an adenylyl cyclase (AC) inhibitor], KT5720 (a PKA inhibitor), or 3-isobutyl-1-methylxanthine (IBMX, a phosphodiesterase inhibitor). The activity levels of AC and PKA, and secreted calcitonin were then measured. The results indicate that thyroxine increases calcitonin secretion, cellular cAMP accumulation, and the activities of AC and PKA, but does not increase hCT mRNA levels in TT cells. BSA-L-T(4) also increases calcitonin secretion. These effects are inhibited by SQ22536, and KT5720 and suggest that the nongenomic thyroxine effects that stimulate calcitonin secretion from TT cells involve the cAMP-dependent PKA pathway.

[Application of cloud-based information platform in China National Birth Cohort].

Birth cohort is an important observational study which can continuously and dynamically collect the exposure changes and health outcomes from gametophyte development to adolescence and even old age. However, because of its complex design and difficult implementation, how to construct birth cohort with high quality and high efficiency is the main difficulty faced by epidemiologists at home and abroad. In 2016, China National Birth Cohort was officially launched. The network and information technology were used to explore, and a set of "cloud-based information platform" was established to support this queue construction, containing 16 units in China. After four years of development, the platform has formed a complete set of programs about the construction of cohort information platform, which including recruitment and follow-up management of participants, real-time data interaction, queue quality control, multi-level authority management and function division. The relevant design framework and functional elements provide the references to the future information construction of large-scale birth cohort and even population-based research in China.

Effect of different types of sugar on gut physiology and microbiota in overfed goose.

To explored the difference of goose fatty liver formation induced-by different types of sugar from the intestinal physiology and the gut microflora, an integrated analysis of intestinal physiology and gut microbiota metagenomes was performed using samples collected from the geese including the normal-feeding geese and the overfed geese which were overfed with maize flour or overfeeding dietary supplementation with 10% sugar (glucose, fructose or sucrose, respectively), respectively. The results showed that the foie gras weight of the fructose group and the sucrose group was heavier (P < 0.05) than other groups. Compared with the control group, the ileum weight was significantly higher (P < 0.01), and the cecum weight was significantly lower in the sugar treatment groups (P < 0.001). Compared with the control group, the ratio of villi height to crypt depth in the fructose group was the highest in jejunum (P < 0.05); the trypsin activity of the ileum was higher in the fructose group and the sucrose group (P < 0.05). At the phylum level, Firmicutes, Proteobacteria and Bacteroidetes were the main intestinal flora of geese; and the abundance of Firmicutes in the jejunum was higher in the sugar treatment groups than that of the maize flour group. At the genus level, the abundance of Lactobacillus in the jejunum was higher (P < 0.05) in the sugar treatment groups than that of the maize flour group. In conclusion, forced-feeding diet supplementation with sugar induced stronger digestion and absorption capacity, increased the abundance of Firmicutes and Bacteroidetes and the abundance of Lactobacillus (especially fructose and sucrose) in the gut. So, the fructose and sucrose had higher induction on hepatic steatosis in goose fatty liver formation.

Biological analysis of flexor tendon repair-failure stump tissue: A potential recycling of tissue for tendon regeneration.

OBJECTIVES: Re-rupture is common after primary flexor tendon repair. Characterization of the biological changes in the ruptured tendon stumps would be helpful, not only to understand the biological responses to the failed tendon repair, but also to investigate if the tendon stumps could be used as a recycling biomaterial for tendon regeneration in the secondary grafting surgery. METHODS: A canine flexor tendon repair and failure model was used. Following six weeks of repair failure, the tendon stumps were analyzed and characterized as isolated tendon-derived stem cells (TDSCs). RESULTS: Failed-repair stump tissue showed cellular accumulation of crumpled and disoriented collagen fibres. Compared with normal tendon, stump tissue had significantly higher gene expression of collagens I and III, matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and insulin-like growth factor (IGF). The stump TDSCs presented both mesenchymal stem and haematopoietic cell markers with significantly increased expression of CD34, CD44, and CD90 markers. Stump TDSCs exhibited similar migration but a lower proliferation rate, as well as similar osteogenic differentiation but a lower chondrogenic/adipogenic differentiation capability, compared with normal TDSCs. Stump TDSCs also showed increasing levels of SRY-box 2 (Sox2), octamer-binding transcription factor 4 (Oct4), tenomodulin (TNMD), and scleraxis (Scx) protein and gene expression. CONCLUSION: We found that a failed repair stump had increased cellularity that preserved both mesenchymal and haematopoietic stem cell characteristics, with higher collagen synthesis, MMP, and growth factor gene expression. This study provides evidence that tendon stump tissue has regenerative potential.Cite this article: C-C. Lu, T. Zhang, R. L. Reisdorf, P. C. Amadio, K-N. An, S. L. Moran, A. Gingery, C. Zhao. Biological analysis of flexor tendon repair-failure stump tissue: A potential recycling of tissue for tendon regeneration. Bone Joint Res 2019;8:232-245. DOI: 10.1302/2046-3758.86.BJR-2018-0239.R1.

From fertilization to gastrulation: axis formation in the mouse embryo.

Although much remains unknown about how the embryonic axis is laid down in the mouse, it is now clear that reciprocal interactions between the extraembryonic and embryonic lineages establish and reinforce patterning of the embryo. At early post-implantation stages, the extraembryonic ectoderm appears to impart proximal-posterior identity to the adjacent proximal epiblast, whereas the distal visceral endoderm signals to the underlying epiblast to restrict posterior identity as it moves anteriorward. At gastrulation, the visceral endoderm is necessary for specifying anterior primitive streak derivatives, which, in turn, pattern the anterior epiblast. Polarity of these extraembryonic tissues can be traced back to the blastocyst stage, where asymmetry has been linked to the point of sperm entry at fertilization.

Atorvastatin does not affect insulin sensitivity and the adiponectin or leptin levels in hyperlipidemic Type 2 diabetes.

BACKGROUND: In addition to lipid lowering, further pleotropic effects of statins have been postulated. We aimed to study if the various pleotropic effects are due indirectly to the modulation of adipocytokines. MATERIALS AND METHODS: We studied the effect of atorvastatin on insulin sensitivity and the plasma adiponectin and leptin concentrations. Our randomized open labeled study had 29 hyperlipidemic Type 2 diabetic patients (14 females, 15 males, mean age 60.0+/-2.2 yr). They were randomized into three 12-week atorvastatin intervention types. Each day patients were given either 10 mg (no.=10), 20 mg (no.=10) or 40 mg (no.=9). Evaluations were performed before and after intervention. RESULTS: All baseline characteristics were statistically identical in the 3 groups. Drop in total cholesterol, LDL-cholesterol, and triglyceride levels were measured at the end. With 10 mg the drop was 30%, 37%, and 30%. The 20 mg group was 43%, 54%, and 34%. The 40 mg group was 42%, 51%, and 27%. Groups had no significant change of body mass index, HDLcholesterol, and glycated hemoglobin levels. Also, levels of insulin, adiponectin, leptin, homeostasis model assessment index (HOMA) and Quantitative Insulin Sensitivity Check Index (QUICKI) stayed the same. Pooled parameters of all 29 patients showed no difference in levels of insulin, adiponectin, leptin, HOMA, and QUICKI before and after treatment. CONCLUSIONS: Atorvstatin does not affect insulin sensitivity and the adiponectin or leptin levels in hyperlipidemic Type 2 diabetes.

Development and Validation of a Natural Language Processing Tool to Identify Patients Treated for Pneumonia across VA Emergency Departments.

BACKGROUND: Identifying pneumonia using diagnosis codes alone may be insufficient for research on clinical decision making. Natural language processing (NLP) may enable the inclusion of cases missed by diagnosis codes. OBJECTIVES: This article (1) develops a NLP tool that identifies the clinical assertion of pneumonia from physician emergency department (ED) notes, and (2) compares classification methods using diagnosis codes versus NLP against a gold standard of manual chart review to identify patients initially treated for pneumonia. METHODS: Among a national population of ED visits occurring between 2006 and 2012 across the Veterans Affairs health system, we extracted 811 physician documents containing search terms for pneumonia for training, and 100 random documents for validation. Two reviewers annotated span- and document-level classifications of the clinical assertion of pneumonia. An NLP tool using a support vector machine was trained on the enriched documents. We extracted diagnosis codes assigned in the ED and upon hospital discharge and calculated performance characteristics for diagnosis codes, NLP, and NLP plus diagnosis codes against manual review in training and validation sets. RESULTS: Among the training documents, 51% contained clinical assertions of pneumonia; in the validation set, 9% were classified with pneumonia, of which 100% contained pneumonia search terms. After enriching with search terms, the NLP system alone demonstrated a recall/sensitivity of 0.72 (training) and 0.55 (validation), and a precision/positive predictive value (PPV) of 0.89 (training) and 0.71 (validation). ED-assigned diagnostic codes demonstrated lower recall/sensitivity (0.48 and 0.44) but higher precision/PPV (0.95 in training, 1.0 in validation); the NLP system identified more "possible-treated" cases than diagnostic coding. An approach combining NLP and ED-assigned diagnostic coding classification achieved the best performance (sensitivity 0.89 and PPV 0.80). CONCLUSION: System-wide application of NLP to clinical text can increase capture of initial diagnostic hypotheses, an important inclusion when studying diagnosis and clinical decision-making under uncertainty.

Development and Evaluation of a Tissue-Engineered Fibrin-based Canine Mitral Valve Three-dimensional Cell Culture System.

Myxomatous mitral valve disease is the most common cardiac disease of the dog, but examination of the associated cellular and molecular events has relied on the use of cadaveric valve tissue, in which functional studies cannot be undertaken. The aim of this study was to develop a three-dimensional (3D) cell co-culture model as an experimental platform to examine disease pathogenesis. Mitral valve interstitial (VIC) and endothelial (VEC) cells were cultured from normal and diseased canine (VIC only) valves. VICs were embedded in a fibrin-based hydrogel matrix and one surface was lined with VECs. The 3D static cultures (constructs) were examined qualitatively and semiquantitatively by light microscopy, immunofluorescence microscopy and protein immunoblotting. Some constructs were manipulated and the endothelium damaged, and the response examined. The construct gross morphology and histology demonstrated native tissue-like features and comparable expression patterns of cellular (α-smooth muscle actin [SMA] and embryonic smooth muscle myosin heavy chain [SMemb]) and extracellular matrix associated markers (matrix metalloproteinase [MMP]-1 and MMP-3), reminiscent of diseased valves. There were no differences between constructs containing normal valve VICs and VECs (type 1) and those containing diseased valve VICs and normal valve VECs (type 2). Mechanical manipulation and endothelial damage (type 3) tended to decrease α-SMA and SMemb expression, suggesting reversal of VIC activation, but with retention of SMemb+ cells adjacent to the wounded endothelium consistent with response to injury. Fibrin-based 3D mitral valve constructs can be produced using primary cell cultures derived from canine mitral valves, and show a phenotype reminiscent of diseased valves. The constructs demonstrate a response to endothelial damage indicating their utility as experimental platforms.

Clostridium innocuum is a vancomycin-resistant pathogen that may cause antibiotic-associated diarrhoea.

OBJECTIVES: Clostridium innocuum can cause extraintestinal infection in patients with underlying diseases. The role of C. innocuum in antibiotic-associated diarrhoea (AAD) remains unknown. METHODS: Clinical information of 103 patients from whom C. innocuum was isolated was reviewed. We carried out cellular and animal experiments to examine the pathogenic potential of C. innocuum in AAD. RESULTS: Eighty-eight per cent (91/103) of the 103 patients received antibiotics within 2 weeks of diarrhoea onset. Patients were further classified into two groups, severe colitis and diarrhoea, according to clinical severity level. The mortality rate was 13.6% (14/103) among the patients from whom C. innocuum was isolated. The lowest concentrations at which 90% of the isolates were inhibited for metronidazole and vancomycin were 0.5 and 16 mg/L, respectively. All isolates tested were susceptible to metronidazole but resistant to vancomycin. Nineteen randomly selected isolates (ten from severe colitis group, nine from diarrhoea group) were subjected to further in vitro cellular examinations. The level of cytotoxicity to Vero cells was significantly higher in isolates from the severe colitis group at both 24 and 48 hours after inoculation (24 and 48 hours, p 0.042 and 0.033, respectively). We observed apoptotic changes that subsequently led to cell death in C. innocuum-infected Vero cells. Tissue damages, necrotic changes and oedema were observed in the mouse ileal loop infected by C. innocuum. CONCLUSIONS: Vancomycin-resistant C. innocuum may play a potential role as a causative agent of AAD. The clinical manifestations of AAD caused by C. innocuum were diarrhoea or severe colitis, including pseudomembranous colitis.

Cytotoxic effects of chemotherapeutic drugs on mouse testis cells.

Studies of testicular cell killing in mice by several chemotherapeutic drugs have been performed to EVALUATE THE HARMFUL EFFECTS OF ONCOLYTIC AGENTS ON REPRODUCTION. Seven drugs, Adriamycin, 1-beta-D-arabinofuranosylcytosine, bleomycin, cyclophosphamide, hydroxyurea, vinblastine, and vincristine, given as single injections, were cytotoxic to differentiated spermatogonia. Adriamycin was also highly effective in killing stem cells. The other drugs produced little or no stem cell loss even at doses toxic to the animals. Negligible killing of spermatocytes and spermatids was noted at any dose level. The results demonstrated that oncolytic agents preferntially killed cells at specific stages of the spermatogenic pathway in mice at doses within the clinical range for humans.