A theory of pitch for the hydrodynamic properties of molecules, helices, and achiral swimmers at low Reynolds number.

We present a theory for pitch, a matrix property that is linked to the coupling of rotational and translational motion of rigid bodies at low Reynolds numbers. The pitch matrix is a geometric property of objects in contact with a surrounding fluid, and it can be decomposed into three principal axes of pitch and their associated moments of pitch. The moments of pitch predict the translational motion in a direction parallel to each pitch axis when the object is rotated around that axis and can be used to explain translational drift, particularly for rotating helices. We also provide a symmetrized boundary element model for blocks of the resistance tensor, allowing calculation of the pitch matrix for arbitrary rigid bodies. We analyze a range of chiral objects, including chiral molecules and helices. Chiral objects with a Cn symmetry axis with n > 2 show additional symmetries in their pitch matrices. We also show that some achiral objects have non-vanishing pitch matrices, and we use this result to explain recent observations of achiral microswimmers. We also discuss the small but non-zero pitch of Lord Kelvin's isotropic helicoid.

Separation of Enantiomers through Local Vorticity: A Screw Model Mechanism.

We present a model to explain the mechanism behind enantiomeric separation under either shear flow or local rotational motion in a fluid. Local vorticity of the fluid imparts molecular rotation that couples to translational motion, sending enantiomers in opposite directions. Translation-rotation coupling of enantiomers is explored using the molecular hydrodynamic resistance tensor, and a molecular equivalent of the pitch of a screw is introduced to describe the degree of translation-rotation coupling. Molecular pitch is a structural feature of the molecules and can be easily computed, allowing rapid estimation of the pitch of 85 druglike molecules. Simulations of model enantiomers in a range of fluids such as Λ- and Δ-[Ru(bpy)3]Cl2 in water and (R, R)- and (S, S)-atorvastatin in methanol support predictions made using molecular pitch values. A competition model and continuum drift-diffusion equations are developed to predict separation of realistic racemic mixtures. We find that enantiomeric separation on a centimeter length scale can be achieved in hours, using experimentally achievable vorticities. Additionally, we find that certain achiral objects can also exhibit a nonzero molecular pitch.

Prospective controlled cohort study of Troponin I levels in patients undergoing elective spine surgery for degenerative conditions: Prone versus supine position.

Prior studies have suggested that elevated serum Troponin-I (TnI) levels immediately after non-cardiac surgical procedures (8-40%) represent subclinical cardiac stress which independently predicts increased 30-day mortality. Routine post-operative TnI monitoring has therefore been suggested as a standard of care. However, no prior studies have focussed on elective degenerative spine surgery, whilst few have measured pre-op TnI. Further, prolonged prone positioning could represent an additional, independent, cardiac stress. We planned a prospective controlled cohort study of consecutive TnI levels in routine elective spine surgery for degenerative spine conditions, incorporating 3 groups: 'prone<2h', 'prone>2h' and 'supine' positioning. TnI levels (>0.04µg/L) were recorded immediately pre-/post-surgery, and by 24h of surgery. N=120 patients were recruited. Complete results were obtained in 92 (39 supine, 53 prone). No significant between-groups differences were observed in demographic or cardiovascular risk factors. Validated TnI-elevation by 24h was not observed in any group. Spurious elevations were recorded in one 'prone<2h' and one 'prone>2h'. One non-ST segment myocardial infarction (STEMI) occurred on day 7 without TnI elevation by 24h (prone>2h). There was no 30-day mortality. CONCLUSIONS: Despite a lower cut-off, no validated TnI elevation was observed in any group by 24h after surgery. One non-STEMI had not been associated with TnI-elevation by 24h. Immediately peri-operative cardiac stress therefore appeared comparatively rare in patients undergoing routine elective spine surgery. Further, prone positioning did not represent an additional, independent, risk. Routine immediately post-operative TnI monitoring in elective spine surgery therefore appears unjustified. Our study highlighted several caveats regarding consecutive TnI testing.

Treatment of diabetic diarrhea and orthostatic hypotension with somatostatin analogue SMS 201-995.

A diabetic patient was treated with a somatostatin analogue, SMS 201-995, to control chronic diarrhea and orthostatic hypotension. The patient was injected with 50 micrograms, 100 micrograms, and 150 micrograms of SMS 201-995 subcutaneously twice daily for three days at each dose. Stool weight decreased from a basal mean value of 906 g per 24 hours to 628 g, 445 g, and 408 g per 24 hours, respectively. Diarrhea remained suppressed for 18 months when the patient was last seen. When SMS 201-995 was then given at 5 micrograms to 10 micrograms per hour by continuous subcutaneous infusion, stool weight decreased to a mean of 321 g per 24 hours. Basal blood pressure, which averaged 99/71 mm Hg, rose to 133/91 mm Hg five minutes after 75 micrograms of SMS 201-995 was injected subcutaneously; it remained elevated for six hours after injection. Serum motilin levels decreased significantly from 126 pg/ml before injection of SMS 201-995 to 52 pg/ml after injection. Serum norepinephrine levels rose from 50 pg/ml supine (normal range, 150 to 550 pg/ml) and 52 pg/ml erect before injection of SMS 201-995 to 72 pg/ml supine and 110 pg/ml erect after injection. SMS 201-995 may raise blood pressure, in part by increasing the release of circulating norepinephrine.

Cycloserine-induced Stevens-Johnson syndrome in an AIDS patient with multidrug-resistant tuberculosis.

We report a case of cycloserine-induced Stevens-Johnson syndrome (SJS) in a 38-year-old male with the acquired immune deficiency syndrome (AIDS) and multidrug resistant tuberculosis (MDR-TB). The patient developed a cutaneous reaction after 60 days of therapy with ofloxacin, streptomycin (SM), pyrazinamide (PZA), ethambutol (EMB), and cycloserine (CSN). All drugs were stopped and the rash improved. Due to the severity of his disease, anti-tuberculosis drugs were resumed, one at a time. The patient developed a recurrent rash consistent with SJS, which began when CSN was restarted. CSN was stopped and the SJS began to gradually resolve with palliative treatment despite continuation of the other anti-tuberculosis drugs. However, the patient's overall condition gradually deteriorated and he died. To our knowledge, this is the first case of probable CSN-related SJS.

Assessing the consistency and educational benefits of students' clinical experiences during an ambulatory care internal medicine rotation.

BACKGROUND: Although ambulatory care settings are being used increasingly in undergraduate clinical education, variability in the depth and breadth of students' contacts with basic medical problems may compromise the educational benefits of this teaching modality. The present study examines the nature of such variation and the educational effectiveness of ambulatory care education. METHOD: During the one-month ambulatory care component of the third-year internal medicine rotation at the University of Michigan Medical School, 43 students in 1989-90 and 1990-91 recorded the patient problems they saw at a hospital and satellite clinics. In addition, the students' diagnostic-recognition abilities were assessed before and after the component. The extents of the students' experiences in various categories of patient problems were quantified and correlated with their diagnostic abilities in relevant content areas. RESULTS: The students saw many categories of problems but few instances in any given category. There were numerous and potentially worrisome gaps in their exposure to several typical ambulatory care problems. Although the students showed significant increases in diagnostic-recognition abilities, these increases were not correlated with the students' levels of experience in any of the relevant problem categories. CONCLUSION: The variability and potentially worrisome gaps in the students' experiences in the ambulatory care settings studied are probably representative of students' experiences in such settings, and should be considered in the implementation and evaluation of educational experiences in ambulatory care.

Analysis of the costs and benefits of using standardized patients to help teach physical diagnosis.

BACKGROUND: Although a majority of medical schools use standardized patients (SPs) for teaching or evaluating students, the costs and benefits of such programs have not been examined in depth. In 1992-93 the Tulane University School of Medicine reduced by 40% the faculty-precepted sessions in its physical diagnosis program in order to incorporate seven focused examinations using SPs to teach basic examination skills. METHOD: Costs for the revised program included costs for SPs, staff, supplies, and faculty. Faculty cost was estimated at a minimum to equal hourly salary and at a maximum to equal this salary plus potential collectible billings. An objective structured clinical examination (OSCE) was used to assess the skill acquisitions of 150 second-year students in 1991-92, before SPs were used, and in 1992-93, when SPs were used. An unpaired t-test was then used to compare the OSCE performances of the two groups of students. Chi-square analysis was used to compare the evaluations of the physical diagnosis program by the 1992-93 and 1991-92 students. RESULTS: The cost of incorporating SPs into the program was $43,800. The amount of time spent teaching by faculty was reduced by 608 hours, costing between $33 (salary) and $108 (salary plus potential revenue) per hour. Thus, the total savings in the cost of faculty time was between $20,064 and $65,664. Despite the reduction in faculty involvement, the students' performance on the OSCE did not change, and the students' evaluations of the course became significantly more favorable. CONCLUSION: The incorporation of SPs as instructors in the physical diagnosis program was accomplished at a minimal cost and resulted in an increase in students' enthusiasm for the purpose, with no loss of skill acquisition as measured by the OSCE.

Electromyographic analysis of selected muscles during sitting push-ups. Effects of position and sex.

The purpose of this study was to determine if differences in EMG activity of the latissimus dorsi, pectoralis major and triceps brachii occurred between muscles and between the 16 male and 16 female subjects performing push-ups from three different sitting positions. Surface electrodes and associated instrumentation recorded a linear envelope during seated push-ups performed 1) in a wheelchair, 2) in a long-sit position with elbows at 90 degrees, and 3) in a long-sit position with maximum elbow flexion and shoulder abduction. Results showed that women produced greater mean EMG activity than men in all muscles at all positions. Altering the exercise position did not have a consistent effect on level of activity recorded from either sex. The study concludes that use of these exercises should be based on a knowledge of the differences in muscle activity in exercise positions for men and women before treatment objectives can be effectively accomplished.

Neurofilament-like immunoreactivity in the sea anemone Condylactis gigantea (Cnidaria: Anthozoa).

The neuronal cytoskeleton contains neurofilament proteins that serve as markers for nervous tissue in many species across phyla. Antiserum generated to mammalian neurofilaments was used for immunocytochemical staining of tissues in the sea anemone Condylactis gigantea (Cnidaria: Anthozoa). Specific staining, visible at the light and electron microscope levels, was found in the tissues of the tentacle. Proteins were extracted from the tissues and solubilized. SDS-polyacrylamide gel electrophoresis and Western blotting revealed two bands of MWr 156 kD and 74 kD that reacted with antiserum generated to neurofilaments. The protein bands also bound a monoclonal antibody shown to react with a highly conserved epitope in many classes of intermediate filaments. These data suggest that the neurons of this anthozoan contain neurofilament-like proteins with molecular properties similar to those of mammalian neurons.

Blunt bile duct injuries in children.

Three of 87 children with blunt liver injuries initially managed without operation required late intervention for bile leakage. Abdominal computed tomography scans in these patients showed liver injuries extending into the porta hepatis. Clinical courses were characterized by persistent abdominal pain, low-grade fever, and prolonged ileus. Radionucleide scan confirmed the suspicion of bile leakage. One patient had complete transection of the common bile duct, which was repaired surgically. Another had partial transection of the left hepatic duct, managed successfully with transampullary biliary decompression. The third patient with an intrahepatic injury was managed with a drain placed at celiotomy. Nonoperative management of blunt pediatric liver injuries carries a risk of persistent bile leakage. Radionucleide scan and endoscopic retrograde cholangiopancreatography are reliable modes of diagnosis and localization. Transampullary biliary decompression is a newer, effective modality for management of the proximal and/or partial bile duct injuries. Treatment must be individualized according to the site and extent of injury.

Resistance training and hormone replacement increase MMP-2 activity, quality and quantity of bone in ovariectomized rats

AIMS: The aim of the present study was to investigate the influence of resistance training (RT) and hormone replacement (HR) on MMP-2 activity, biomechanical and physical properties bone of ovariectomized (OVX) rats. METHODS: Sprague-Dawley female rats were grouped into six experimental groups (n = 11 per group): sham-operated sedentary (SHAM Sed), ovariectomized sedentary (OVX Sed), sham-operated resistance training (SHAM RT), ovariectomized resistance training (OVX RT), ovariectomized sedentary hormone replacement (OVX Sed-HR), and ovariectomized resistance training hormone replacement (OVX RT-HR). HR groups received implanted silastic capsules with a 5% solution of 17ß-estradiol (50 mg 17ß-estradiol/ml of sunflower oil). In a 12-week RT period (27 sessions; 4-9 climbs) the animals climbed a 1.1 m vertical ladder with weights attached to their tails. Biomechanical and physical bone analyses were performed using a universal testing machine, and MMP-2 activity analysis was done by zymography. RESULTS: Bone density and bone mineral content was higher in the RT and HR groups. The MMP-2 activity was higher in the RT and HR groups. The biomechanical analysis (stiffness, fracture load and maximum load) demonstrated better bone tissue quality in the RT associated with HR. CONCLUSION: The RT alone as well as when it is associated with HR was efficient in increasing MMP-2 activity, biomechanical and biophysical properties bone of ovariectomized rats.(AU)

Spontaneous bacterial peritonitis in Wilson's disease.

Spontaneous bacterial peritonitis associated with Wilson's disease has been previously reported in only one case. We report two cases where this infection developed and seriously complicated the course of illness. As with spontaneous bacterial peritonitis occurring with other underlying diseases, early diagnosis and treatment are critical to improved outcome. Recognition that it can occur with Wilson's disease is important, and paracentesis should be performed without delay when suspicious features are present.

Career preferences and career outcomes of Australian medical students.

Students entering three Australian medical schools were followed over a 15-year period to trace both movement into the profession and the longer-term outcomes of early career aspirations. A variety of student entry characteristics are examined together with aspirations, attainments and self-images. The results indicate that women, rather than men, are more likely to enter medical school with aspirations that involve specialty training. As they proceed through medical school, both groups move away from the idea of pursuing specialty training, although women tend to decide earlier than men that specialty practice is not for them. Women students are more likely than men to attain career goals if these involve general practice and less likely to if these involve specialization. The results indicate that although at graduation women medical practitioners have the same career goals and desires as men, if additional training is required women are unlikely to have their aspirations fulfilled.

Functional properties of lymphocyte subpopulations in hepatitis B virus infection. I. Suppressor cell control of T lymphocyte responsiveness.

Hepatocellular injury in hepatitis B virus infection may be produced by an autoaggressive hepatocytotoxic immune response. To test the hypothesis that acquired suppressor cell defects may participate in such a response, we assessed the functional integrity of 2 suppressor cell populations in patients with type B viral hepatitis. Spontaneous suppression of the 1-way mixed lymphocyte response by radiation-resistant, adherent peripheral blood mononuclear cells decreases during the acute phase of disease, returns towards normal with clinical recovery, but remains depressed in patients with chronic hepatitis. The degree of spontaneous suppressor cell dysfunction correlates inversely with at least 1 biochemical parameter of hepatocellular injury (SGPT). The functional integrity of this suppressor cell fluctuates during chronic hepatitis and may reflect currently undefined biologic variables in this disease. Mitogen-induced suppression on lymphocyte activation by radiation resistant, nonadherent suppressor cells is also depressed in acute and chronic hepatitis, but it does not correlate with biochemical evidence of hepatocellular injury on an individual-patient basis. Documentation of these generalized defects of nonspecific suppressor cell function establishes a basis for the possible existence of specific anomalies of immuno-regulation that may permit the expression of normally suppressed auoaggressive hepatocytotoxic immune mechanisms in viral hepatitis.

Functional properties of lymphocyte subpopulations in hepatitis B virus infection. II. Cytotoxic effector cell killing of targets that naturally express hepatitis B surface antigen and liver-specific lipoprotein.

Cytotoxic effector cell responsiveness to host and/or virus-determined hepatocyte surface membrane antigens has been postulated as an important pathogenetic determinant of hepatocellular injury in hepatitis B virus infection. Assuming that such effector cell populations would be detectable in peripheral blood, the present study was designed to examine 2 questions: first, whether target cells that normally express liver-specific protein (LSP) and hepatitis B surface antigen (HBsAg) are selectively destroyed by peripheral blood effector cells from patients with viral hepatitis; second, whether cytotoxic effector cell function emerges coincident with the development of defective suppressor cell activity in the same patients. No evidence of increased HBsAg or LSP specific cytotoxic effector cell activity was found in the peripheral blood natural killer (NK) or T killer cell populations of patients with acute or chronic viral hepatitis.