Accessible chromatin maps of inflammatory bowel disease intestine nominate cell-type mediators of genetic disease risk

Inflammatory Bowel Disease ( IBD ) is a chronic and often debilitating autoinflammatory condition, with an increasing incidence in children. Standard-of-care therapies lead to sustained transmural healing and clinical remission in fewer than one-third of patients. For children, TNFα inhibition remains the only FDA-approved biologic therapy, providing an even greater urgency to understanding mechanisms of response. Genome-wide association studies ( GWAS ) have identified 418 independent genetic risk loci contributing to IBD, yet the majority are noncoding and their mechanisms of action are difficult to decipher. If causal, they likely alter transcription factor ( TF ) binding and downstream gene expression in particular cell types and contexts. To bridge this knowledge gap, we built a novel resource: multiome-seq (tandem single-nuclei ( sn )RNA-seq and chromatin accessibility ( snATAC )-seq) of intestinal tissue from pediatric IBD patients, where anti-TNF response was defined by endoscopic healing. From the snATAC-seq data, we generated a first-time atlas of chromatin accessibility (putative regulatory elements) for diverse intestinal cell types in the context of IBD. For cell types/contexts mediating genetic risk, we reasoned that accessible chromatin will co-localize with genetic disease risk loci. We systematically tested for significant co-localization of our chromatin accessibility maps and risk variants for 758 GWAS traits. Globally, genetic risk variants for IBD, autoimmune and inflammatory diseases are enriched in accessible chromatin of immune populations, while other traits (e.g., colorectal cancer, metabolic) are enriched in epithelial and stromal populations. This resource opens new avenues to uncover the complex molecular and cellular mechanisms mediating genetic disease risk.

A plausibly causal functional lupus-associated risk variant in the STAT1-STAT4 locus

Systemic lupus erythematosus (SLE or lupus) (OMIM: 152700) is a chronic autoimmune disease with debilitating inflammation that affects multiple organ systems. The STAT1-STAT4 locus is one of the first and most highly replicated genetic loci associated with lupus risk. We performed a fine-mapping study to identify plausible causal variants within the STAT1-STAT4 locus associated with increased lupus disease risk. Using complementary frequentist and Bayesian approaches in trans-ancestral Discovery and Replication cohorts, we found one variant whose association with lupus risk is supported across ancestries in both the Discovery and Replication cohorts: rs11889341. In B cell lines from patients with lupus and healthy controls, the lupus risk allele of rs11889341 was associated with increased STAT1 expression. We demonstrated that the transcription factor HMGA1, a member of the HMG transcription factor family with an AT-hook DNA-binding domain, has enriched binding to the risk allele compared with the non-risk allele of rs11889341. We identified a genotype-dependent repressive element in the DNA within the intron of STAT4 surrounding rs11889341. Consistent with expression quantitative trait locus (eQTL) analysis, the lupus risk allele of rs11889341 decreased the activity of this putative repressor. Altogether, we present a plausible molecular mechanism for increased lupus risk at the STAT1-STAT4 locus in which the risk allele of rs11889341, the most probable causal variant, leads to elevated STAT1 expression in B cells due to decreased repressor activity mediated by increased binding of HMGA1.

Single-institution experience comparing double-barreled wet colostomy to ileal conduit for urinary and fecal diversion

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Background: Patients with advanced primary or recurrent colorectal cancers that undergo total pelvic exenteration for cure or palliation require proximal urinary and fecal diversion. The most commonly used diversion technique is use of an ileal conduit (IC) and end colostomy. At our institute, the double-barreled wet colostomy (DBWC) has been shown to be have similar outcomes and technically feasible.

Methods: Between 2004 and 2010, 37 patients underwent total pelvic exenteration for advanced primary or recurrent colorectal cancer. Two groups were identified based on the technique used for their urinary diversion, either by way of an IC (n = 4) or DBWC (n = 33). Demographics, periprocedural events, and outcomes were compared between the two groups.

Results: The two groups were similar in the terms of age, gender, and comorbidities. Thirty-three patients (89%) underwent a DBWC and four patients (11%) underwent an IC. All of these patients underwent a total pelvic exenteration for advanced primary (27%) or recurrent colorectal cancer (73%) either for cure or for palliation. Twenty patients underwent R0 resection (54%), and 17 patients had non-R0 resection (46%). Complications, length of stay, and operative times between both groups were similar. Median survival for both groups showed no statistical difference.

Conclusions: DBWC is a safe and feasible alternative to the traditional ileal conduit for urinary diversion. It provides a single stoma to care for, and an intact contralateral abdominal muscle to use as a vertical rectus abdominus musculocutaneous flap for reconstruction. This technique is easy to learn and is not associated with higher operative times, length of stay, morbidity, or mortality.

[Table: see text]

No significant financial relationships to disclose.

Oxygen cost of sprint training

AIM

The purpose of the study was to profile the oxygen uptake of sprinters during various portions of a typical sprint training workout.

METHODS

This was a descriptive study of 11 female sprinters and jumpers on an NCAA Division II university track team. Subjects were assessed for VO(2max), and VO(2) and HR kinetics during a 65 min typical sprint training session on a treadmill. The sprint session included a warm-up, static stretching, acceleration runs, 8x20 s sprints at 150% of velocity VO(2max) (vVO(2max)) with a 3-min walk recovery, and a cool-down.

RESULTS

Mean VO(2) and HR (M+/-SD) for the entire 65 min sprint training session were 19.1+/-7.6 mL/kg/min and 138.7+/-24.0 b/min, respectively. VO(2) rose to 33 mL/kg/min during and immediately following each 20 s sprint which represented 73% of VO(2max). VO(2) during and after each sprint remained nearly constant (P>0.05) rather than rising as hypothesized.

CONCLUSION

VO(2) during a 65 min sprint training workout in female college athletes varies greatly but was elevated to 33 mL/kg/min following each 20 s sprint. VO(2) did not rise across the series of eight sprints. These results suggest that chronic sprint training may elicit a moderate aerobic training effect. Implications for training are discussed.

The antennal system and cockroach evasive behavior. II. Stimulus identification and localization are separable antennal functions

Cockroaches ( Periplaneta americana) orient their antennae toward moving objects based on visual cues. Presumably, this allows exploration of novel objects by the antennal flagellum. We used videographic and electrophysiological methods to determine if receptors on the flagellum are essential for triggering escape, or if they enable cockroaches to discriminate threatening from non-threatening objects that are encountered. When a flagellum was removed, and replaced with a plastic fiber, deflection of a "prosthetic flagellum" still activated the descending mechanosensory interneurons associated with escape and produced typical escape responses. However, escape was essentially eliminated by constraining the movement of the scape and pedicel at the antennal base. When cockroaches approached and briefly explored the surface of a spider or another cockroach with the flagellum, they produced escape significantly more often in response to subsequent controlled contact from a spider than from a cockroach. This discrimination did not depend on visual or wind-sensory input, but required flagellar palpation of the surface. The crucial sensory cues appear to involve texture rather than surface chemicals. These results indicate that cockroaches acquire basic information on stimulus identity during exploration of surfaces with flagellar receptors, but that basal receptors are triggers for escape behavior.

Xenoendocrine disrupters-tiered screening and testing: filling key data gaps

The US Environmental Protection Agency (EPA) is developing a screening and testing program for endocrine disrupting chemicals (EDCs) to detect alterations of hypothalamic-pituitary-gonadal (HPG) function, estrogen (ER), androgen (AR) and thyroid hormone synthesis and AR and ER receptor-mediated effects in mammals and other animals. High priority chemicals would be evaluated in the Tier 1 Screening (T1S) battery and chemicals positive in T1S would then be tested (Tier 2). T1S includes in vitro ER and AR receptor binding and/or gene expression, an assessment of steroidogenesis and mammalian (rat) and nonmammalian in vivo assays (Table 1). In vivo, the uterotropic assay detects estrogens and antiestrogens, while steroidogenesis, antithyroid activity, (anti)estrogenicity and HPG function are assessed in a 'Pubertal Female Assay'. (Anti-) androgens are detected in the Hershberger Assay (weight of AR-dependent tissues in castrate-immature-male rats). Fish and amphibian assays also are being developed. The fathead minnow assay can identify EDCs displaying several mechanisms of concern, including AR and ER receptor agonists and antagonists and inhibitors of steroid hormone synthesis. An amphibian metamorphosis assay is being developed to detect thyroid-active substances. Several alternative mammalian in vivo assays have been proposed. Of these, a short-term pubertal male rat assay appears most promising. An in utero-lactational screening protocol also is being evaluated. For Tier 2, the numbers of endocrine sensitive endpoints and offspring (F1) examined in multigenerational tests need to be expanded for EDCs. Consideration should be given to tailoring T2, based on the results of T1S. Tier 1 and 2 also should examine relevant mixtures of EDCs. Toxicants that induce malformations in AR-dependent tissues produce cumulative effects even when two chemicals act via different mechanisms of action.

Post-operative analgesia following total knee replacement: an evaluation of the addition of an obturator nerve block to combined femoral and sciatic nerve block

BACKGROUND

Femoral and sciatic nerve block may not provide complete post-operative analgesia following total knee replacement. This study was designed to evaluate whether the addition of an obturator nerve block to combined femoral and sciatic nerve block improves the quality of post-operative analgesia following primary total knee replacement.

METHODS

Sixty patients were randomised into one of two groups: combined femoral and sciatic nerve block with 15 ml 0.75% ropivacaine to each nerve or combined femoral and sciatic nerve block with 15 ml 0.75% ropivacaine to each nerve and an obturator nerve block with 5 ml 0.75% ropivacaine.

RESULTS

Peripheral nerve blocks were successful in 85% of patients. The group which received the obturator nerve block showed a significant increase in the time until their first request for analgesia (mean 257.0 vs. 433.6 min) and a significant reduction in the total requirements for morphine throughout the study period (mean 83.8 vs. 63.0 mg) (P<0.05). There were no systemic or neurological sequelae in any of the groups.

CONCLUSIONS

The addition of an obturator nerve block to femoral and sciatic blockade improved post-operative analgesia following total knee replacement.

Intrathecal ropivacaine for total hip arthroplasty: double-blind comparative study with isobaric 7.5 mg ml(-1) and 10 mg ml(-1) solutions

This study was designed to evaluate the efficacy and safety of two concentrations of intrathecal ropivacaine, 7.5 and 10 mg ml(-1), in patients undergoing total hip arthroplasty. One hundred and four patients, ASA I-III, were randomized to receive an intrathecal injection of one of two concentrations of isobaric ropivacaine. Group 1 (n=51) received 2.5 ml of 7.5 mg ml(-1) ropivacaine (18.75 mg). Group 2 (n=53) received 2.5 ml of 10 mg ml(-1) ropivacaine (25 mg). The onset and offset of sensory block at dermatome level T10, maximum upper and lower spread of sensory block and the onset, intensity and duration of motor block were recorded, as were safety data. Onset of motor and sensory block was rapid with no significant differences between the two groups. The median time of onset of sensory block at the T10 dermatome was 2 min (range 1-25 min) in Group 1 and 2 min (range 1-21 min) in Group 2. The median duration of sensory block at the T10 dermatome was 3.0 h (range 0.5-4.2 h) in Group 1 and 3.4 h (1.1-5.9 h) in Group 2 (P=0.002). The median duration of complete motor block was significantly prolonged (P<0.05) in Group 2 compared with Group 1 (1.9 vs 1.2 h, respectively). Anaesthetic conditions were excellent in all but one patient. Intrathecal ropivacaine, in doses of 18.75 and 25 mg, was well tolerated and provided effective anaesthesia for total hip arthroplasty.

The accuracy of the ACSM stair-stepping equation

PURPOSE

The purpose of this study was to determine the accuracy of the ACSM equation used to estimate the oxygen cost of stepping exercise. The equation appears as: VO2 (mL.kg(-1).min(-1)) = 0.2 (steps.min(-1)) + (step height, m x steps.min(-1) x 2.4) + 3.5.

METHODS

Subjects were 55 men and women between the ages of 19 and 35 yr. Steady-state VO2 was measured at six different combinations of step heights and step rates. Step heights were 0.1, 0.2, and 0.3 m (4, 8, and 12 in, respectively) and step rates were 20 and 25 steps.min(-1). Predicted VO2 for each workload was derived from the ACSM equation.

RESULTS

Mean differences between actual and predicted VO2 values ranged from -0.2 to -1.1 mL.kg(-1).min(-1) and was -0.6 mL.kg(-1).min(-1) for all workloads combined. All differences except the lowest were significant (P < or = 0.05). Total errors ranged from 1.3 to 2.5 mL.kg(-1).min(-1) and was 1.9 mL.kg(-1).min(-1) for all workloads combined. For all workloads combined, the correlation between actual and predicted VO2 was r = 0.95 with a SEE = 1.7 mL.kg(-1).min(-1). The statistics are comparable to other ACSM prediction equations.

CONCLUSION

Although all of the mean differences except one were statistically significant, they were judged negligible from a practical standpoint. Therefore, it was concluded that the ACSM equation is an accurate predictor of the oxygen cost of stair-stepping exercise.

Effects of environmental antiandrogens on reproductive development in experimental animals

Chemicals that act as androgen receptor (AR) agonists and antagonists or inhibit fetal steroidogenesis can induce reproductive malformations in humans and laboratory animals. Several environmental chemicals disrupt development in rats and/or rabbits at fetal concentrations at, or near, exposure levels seen in some segments of the human population. In rats, fetal tissues concentrations of 10-20 p.p.m. of the DDT metabolite, p,p'-DDE, are correlated with reproductive abnormalities in male offspring. These concentrations are similar to those measured in first-trimester human fetal tissues in the late 1960s. The pesticides vinclozolin, procymidone, linuron and DDT are AR antagonists. They reduce male rat anogenital distance, and induce areolas at relatively low dosages. Hypospadias, agenesis of the sex accessory tissues and retained nipples are seen in the middle dosages, while undescended testes and epididymal agenesis are seen in the highest doses. Phthalate esters (PE) inhibit testosterone synthesis during fetal life, but do not appear to be AR antagonists. Prenatal administration of a single low dose of dioxin (50-1,000 ng TCDD/kg) alters the differentiation of androgen-dependent tissues at p.p.t. concentrations, but the mechanism of action likely involves interaction with a hormone-like nuclear transcription factor, the hormone-like receptor AhR, rather than AR. p,p'-DDT and p,p'-DDE, vinclozolin and di-n-butyl phthalate affect reproductive function in rabbits when administered during prenatal and/or neonatal life. Cryptorchidism and carcinoma in situ-like (CIS) testicular lesions were seen in male rabbits treated during development with p,p'-DDT or p,p'-DDE. Extrapolation of effects from rodents to humans would be enhanced if future studies incorporate determination of tissue concentrations of the active metabolites. Knowledge of the tissue concentrations of the active toxicants also would provide an important link to in-vitro studies, which provide more useful mechanistic information when they are executed at relevant concentrations.

"So that our souls don't get damaged": the impact of racism on maternal thinking and practice related to the protection of daughters

Racism influences the conceptualization of motherhood and the practice of mothering. Narrative analysis was completed on 246 stories collected through five focus groups. Twenty-five African American women participated in the study. The results indicate that living in a racist society profoundly impacts the maternal thinking and practice of African American women in relation to protecting their daughters. Protection of children was viewed as a communal responsibility. Issues related to the provision of safe and nurturing physical, aesthetic, and spiritual environments are addressed. The influence that maternal responsibilities have on women's own health is also discussed. Suggestions are provided for mental health providers who wish to work more effectively with African American women.

Perinatal exposure to the phthalates DEHP, BBP, and DINP, but not DEP, DMP, or DOTP, alters sexual differentiation of the male rat

In mammals, exposure to antiandrogenic chemicals during sexual differentiation can produce malformations of the reproductive tract. Perinatal administration of AR antagonists like vinclozolin and procymidone or chemicals like di(2-ethylhexyl) phthalate (DEHP) that inhibit fetal testicular testosterone production demasculinize the males such that they display reduced anogenital distance (AGD), retained nipples, cleft phallus with hypospadias, undescended testes, a vaginal pouch, epididymal agenesis, and small to absent sex accessory glands as adults. In addition to DEHP, di-n-butyl (DBP) also has been shown to display antiandrogenic activity and induce malformations in male rats. In the current investigation, we examined several phthalate esters to determine if they altered sexual differentiation in an antiandrogenic manner. We hypothesized that the phthalate esters that altered testis function in the pubertal male rat would also alter testis function in the fetal male and produce malformations of androgen-dependent tissues. In this regard, we expected that benzyl butyl (BBP) and diethylhexyl (DEHP) phthalate would alter sexual differentiation, while dioctyl tere- (DOTP or DEHT), diethyl (DEP), and dimethyl (DMP) phthalate would not. We expected that the phthalate mixture diisononyl phthalate (DINP) would be weakly active due to the presence of some phthalates with a 6-7 ester group. DEHP, BBP, DINP, DEP, DMP, or DOTP were administered orally to the dam at 0.75 g/kg from gestational day (GD) 14 to postnatal day (PND) 3. None of the treatments induced overt maternal toxicity or reduced litter sizes. While only DEHP treatment reduced maternal weight gain during the entire dosing period by about 15 g, both DEHP and DINP reduced pregnancy weight gain to GD 21 by 24 g and 14 g, respectively. DEHP and BBP treatments reduced pup weight at birth (15%). Male (but not female) pups from the DEHP and BBP groups displayed shortened AGDs (about 30%) and reduced testis weights (about 35%). As infants, males in the DEHP, BBP, and DINP groups displayed femalelike areolas/nipples (87, 70, and 22% (p < 0.01), respectively, versus 0% in other groups). All three of the phthalate treatments that induced areolas also induced a significant incidence of reproductive malformations. The percentages of males with malformations were 82% (p < 0.0001) for DEHP, 84% (p < 0.0001) for BBP, and 7.7% (p < 0.04) in the DINP group. In summary, DEHP, BBP, and DINP all altered sexual differentiation, whereas DOTP, DEP, and DMP were ineffective at this dose. Whereas DEHP and BBP were of equivalent potency, DINP was about an order of magnitude less active.

Muscular endurance and wheelchair propulsion in children with cerebral palsy or myelomeningocele

Bivariate correlations between muscular endurance or resistance used during six-repetition maximum (6-RM) for eight upper body exercises (shoulder flexion, extension, abduction, internal and external rotation, elbow flexion, extension and shoulder flexion/elbow extension (bench press), 50-meter dash, and 12-minute wheelchair propulsion tests were examined in six children with diagnoses of cerebral palsy or myelomeningocele. Correlations were determined before and after resistance training. Before training, only elbow extension correlated significantly with the 12-minute test. Following training, significant correlations (p less than or equal to 0.05) were found between all 6-RM exercises and 12-minute test scores. Additionally, significant correlations were found between all 6-RM exercises (except elbow flexion, which approached significance) and 50-meter dash scores. The results of this clinical case investigation indicate that the relationship between muscular endurance (6-RM) and wheelchair propulsion improves as muscular endurance increases.

Stimulation of peripheral blood T cells by an activated T-cell line: a novel human autologous T-T lymphocyte reaction

T lymphocyte interactions have generally been described between discrete functional subsets. In our investigation of murine T-cell interactions we described a type of T-T interaction termed the 'Syngeneic T-T Lymphocyte Reaction' in which activated T-cell clones stimulated the proliferation of resting T cells mainly through a mechanism involving cell to cell contact. To investigate whether similar reactions occur in the human immune system we used the human autoreactive T-cell line C.1 to stimulate peripheral T cells. Line C.1 cells, which are not transformed and do not secrete IL2, consistently caused proliferation of purified freshly isolated autologous peripheral human T cells as measured by a [3H]-thymidine incorporation assay. The proliferation was seen in both the CD4 and CD8 subsets and could be inhibited with anti-DR and anti-CD2 antibodies. The stimulation is not due to carryover of classical antigen-presenting cells or to the C.1 line cells acting as antigen-presenting cells. We propose that some activated T cells, probably by expression of a surface molecule, can stimulate resting T cells thereby allowing for antigen-non-specific augmentation of the immune response.

Triphasic response of prostacyclin production in rabbit thoracic aorta in early atherosclerosis

Atherosclerosis was induced in male rabbits by administration of a 2% cholesterol diet for up to 18 weeks. The animals were assessed for aortic microsomal prostanoid synthesis, morphologic assessment and serum cholesterol levels. Serum levels of cholesterol increased from control values of 84 +/- 9 ng/dl to 1632 +/- 227 ng/dl at 2 weeks (20-fold increase), and 4859 +/- 829 ng/dl at 9 weeks (57-fold increase). Aortic microsomal prostacyclin synthesis fell significantly at 2 weeks of cholesterol feeding which predated the morphologic appearance of atherosclerotic plaque in the 7 week group. Aortic microsomal PGI2 synthesis significantly increased by 7 weeks and did not fall until the 18 week group when a highly significant increase in aortic plaque developed. These findings suggest a triphasic response of aortic PGI2 synthesis with the development of early atherosclerosis. Phase one is a fall in aortic PGI2 synthesis which predates the appearance of plaque. In phase 2, a significant rise in aortic PGI2 with the appearance of plaque could represent compensation of aortic endothelium to prevent further plaque development. In phase 3, decreased aortic PGI2 could indicate replacement of normal endothelium by atherosclerotic plaque.

Common bile duct ligation in rabbit: a new model of acute cholecystitis description of histology and bile analysis

The early stages of acute cholecystitis have been difficult to investigate due to the animal models developed and utilized over the past 60 years. A new model of animal acute cholecystitis induced by common bile duct ligation in the rabbit for 1 to 4 days produces histologic changes which are nearly identical to acute human cholecystitis. These changes include subserosal edema, hemorrhage, white cell infiltration, and dilatation of lymphatics. An inflammation scoring system is described with a range from 0 (not present) to 11 (the most severe). The inflammation score was 2 +/- 0.7 in control rising to 6.3 +/- 1.2 at 1 day of ligation and increasing further with time of duct ligation (P less than 0.01 all groups compared to control). Analysis of bile lithogenic index and concentrations of cholesterol, bile acids, and phospholipids showed no differences among control and experimental groups. Our findings show that the model of rabbit common bile duct ligation produces a histologic picture identical to human cholecystitis without chemical or physical manipulation of the gallbladder or significant changes in the bile lithogenic index.

Elevated PGI2 and PGE2 production in the rat ileum following mild hypotension

Ileal prostaglandin (PGs) biosynthesis was compared in female rats in normal mild hemorrhage (exposed to mild hypotension, reperfusion, and maintenance on hyperalimentation for 5 days) and control groups (instrumentation and hyperalimentation without hemorrhage). Tissue PG levels were analyzed by radiochromatographic analysis of microsomal membrane fractions prepared from the ileum in each group. Total cyclooxygenase activity in the normal and control groups was modest, with low levels of 6-keto-PGF1 alpha, PGE2, PGF2 alpha, thromboxane B2, PGA2, and PGD2 being produced. Hemorrhage, reperfusion, and maintenance on hyperalimentation for 5 days markedly induced total cyclooxygenase activity in the female rat ileum. Ileal microsomal membrane fractions obtained from the mild hemorrhage group synthesized levels of individual PGs three- to seven-fold higher than the normal or control groups, with 6-keto- PGF1 alpha (breakdown product of prostacyclin), PGE2, and PGA2 demonstrating the highest levels of biosynthesis. These data suggest that the gastrointestinal tract could serve as a source for the elevated PGs known to occur in various shock models.

Effects of sex hormones on rabbit gallbladder prostaglandin biosynthesis

The influence of sex hormones on female and male rabbit gallbladder prostaglandin biosynthesis was examined by radiochromatographic analysis of microsomal membrane fractions. Normal male rabbit total cyclooxygenase activity was modest, producing small amounts of PGE2, PGF2 alpha and 6-keto-PGF1 alpha (breakdown product of PGI2). The normal female gallbladder (GB) microsomes demonstrated an increase in total cyclooxygenase activity when compared to the normal male rabbit gallbladder microsomes. The major prostaglandin (PG) products produced were 6-keto-PGF1 alpha, PGE2 (fivefold higher activity than the male), and PGF2 alpha. The effect of exogenous sex hormones was studied by comparing GB PG biosynthesis in male rabbits treated with exogenous estrogen (50 micrograms/kg sub Q X 5 days) and female rabbits treated with exogenous testosterone (2.5 mg/kg sub Q X 5 days). Exogenous estrogen significantly increased total cyclooxygenase activity in the male rabbit GB microsomes with a significant increase in 6-keto-PGF1 alpha production when compared to the normal male. Exogenous testosterone significantly decreased female rabbit GB total cyclooxygenase activity with a significant decrease in PGE2 biosynthesis and a substantial lowering in 6-keto-PGF1 alpha production. These data suggest that the major sex hormones, estrogen and testosterone, have potent but opposite effects on rabbit GB PG biosynthesis. Both sex hormones may contribute to the sex differences found in our original studies in rabbit GB biosynthesis.

Facile autoplast generation and transformation in Bacillus thuringiensis subsp. kurstaki

We describe a method for maximizing the rate of conversion of Bacillus thuringiensis subsp. kurstaki vegetative cells to osmotically fragile forms in the absence of exogenously added enzymes. Optimal generation of autoplasts occurred in 50 mM sodium acetate buffer (pH 7.0) at 37 degrees C with 10% (wt/vol) polyethylene glycol as an osmotic stabilizer. The maximum autolytic rate resulted in a conversion of greater than 90% of bacilli to spherical autoplasts in 6 min. Autoplasts regained bacillary morphology upon plating on DM3-G regeneration medium, with reversion frequencies ranging from 1.2 x 10(-1) to 5.3 x 10(-3). The autoplasts could efficiently take up exogenously added plasmid DNA. The presence of plasmids was verified by Southern hybridization analysis.

Suggestions for use of behavioral measures in treating bruxism

Nonfunctional grinding and gnashing of teeth during sleep is a behavior known as nocturnal bruxism, which affects a significant number of persons. It may lead to serious dental problems. Current practices by dentists and psychologists involve EMG monitoring of masseter muscle tension and contingent arousal for bruxing. Here assumed efficacy of arousal combined with overcorrection procedures rather than use of arousal alone guides treatment. Intermittent contingency schedules have been effective in long-term maintenance and generalization of behaviors.

Nucleoid structure in freeze fractures of Streptococcus faecalis: effects of filtration and chilling

With the techniques used in this study, the nucleoid of Streptococcus faecalis could not be seen in freeze-etch preparations unless glutaraldehyde had been added to cultures of cells before they were frozen. With time, the nucleoid became visible as a network of fibers, apparently as a result of the aggregation of individual chromosomal elements in the presence of glutaraldehyde. When glutaraldehyde was added to undisturbed cultures, the fibers that became visible were observed in small patches that were seemingly scattered throughout the cytoplasm. However, if cells were chilled or placed on filters before glutaraldehyde was added, the fibers which then developed were seen in large central areas. The appearance of centralized nucleoids in freeze fractures of cells that had been chilled or filtered could be correlated with a decrease in the central density of the cytoplasm, as seen by light microscopy, in cells embedded in gelatin or bovine serum albumin. These observations are discussed in relation to a model for the normal structure of the nucleoid which suggests that the treatments routinely used to study the morphology-physiology of cells (chilling, filtration, and fixation) result in a reorganization of the cytoplasm, leading to an increase in the centralization of nuclear material.

Temporary vascular bypass for perfusion of a renal transplant during abdominal aneurysmectomy

A temporary vascular bypass was utilized to maintain perfusion of a renal transplant during abdominal aortic aneurysmectomy. The shunt, of polyvinyl tubing, was placed between the upper abdominal aorta and the common iliac artery, where the perfusion pressure was only 15 mm Hg less than systemic pressure. The transplanted kidney fuctioned normally during 71 minutes of aortic cross clamping, and there was no evidence of postoperative renal failure.