Dentin permeability: effects of crown preparation

Sequential crown reductions of extracted human teeth were made to evaluate both regional differences in dentin permeability and the effects of tooth reduction. Two different methods of tooth reduction were used. In group 1, tooth reduction was nonuniform but was done in a manner similar to conventional crown preparations. Maximum, total crown permeability was measured using a pressurized fluid filtration technique after removing the smear layer. Regional reductions in permeability were accomplished by creating smear layers on mesial, distal, buccal, lingual, and occlusal surfaces sequentially. Between each step, changes in dentin permeability were measured. In group 2, tooth reductions were uniform and regional permeability was reduced by localized application of potassium oxalate. Both methods demonstrated increased permeability of dentin as the prepared surfaces approached the pulp chamber. Generally, the mesial surfaces were more permeable than the distal surfaces. The occlusal and lingual surfaces were the least permeable regions.

Repair of shoulder luxation in a horse

Shoulder luxation in a 3-year-old Thoroughbred filly was treated by closed reduction, using a calf jack to provide traction on the limb. Arthroscopic examination of the shoulder allowed removal of soft tissue and bony debris. After surgery, the filly was confined to a box stall for 6 months. Eight months after surgery, the filly was doing light work and was not lame. Muscular atrophy present before surgery had resolved. Use of a calf jack may allow reduction of shoulder luxation under field conditions.

The cutaneous microcirculation of the forearm in young and old subjects

Previous studies have shown a reduced cutaneous circulatory response to direct heat stress in the forearm circulations of older (60 to 80 year) subjects. The purpose of this study was to test the hypothesis that this aging effect is due to a reduced ability of the cutaneous microvessels in the forearm to respond to direct heat. Two groups of male subjects consented to participate; a group of 15 young individuals (Y; 20-39 year) and a group of 11 older (O; 60-79 year) individuals. The subjects rested in a supine position with the right forearm situated on the stage of a Leitz epiilumination microscope which was used to view the superficial cutaneous microvessels. The width of the red cell column (WRC), an index of vascular diameter, and the blood cell velocity (BCV) within the microvessels were measured by videomicroscopy at the presenting skin temperature (Ts) of 32 degrees, and then again after Ts had been elevated to 35 degrees then 40 degrees. At a Ts of 32 degrees, WRC and BCV for the Y group, respectively, averaged 6.6 microns and 0.22 mm/sec. Corresponding averages for the O subjects were 8.4 microns and 0.17 mm/sec. Between-group differences were not significant. At a skin temperature of 40 degrees, BCV was significantly higher compared to that at 32 degrees and 35 degrees for both groups (P less than 0.05); whereas, WRC did not significantly change. There were no significant between-group differences in BCV at the higher two temperatures. These results argue against a diminished blood flow response of superficial microvessels being responsible for the reduced cutaneous circulatory response to heat stress in older individuals.

Studies on yeast nucleoside triphosphate-nucleoside diphosphate transphosphorylase (nucleoside diphosphokinase). IV. Steady-state kinetic properties with thymidine nucleotides (including 3'-azido-3'-deoxythymidine analogues)

A study of the steady-state kinetics of the crystalline brewer's yeast (Saccharomyces carlsbergensis) nucleoside diphosphokinase, with the magnesium complexes of the adenine and thymidine nucleotides as reactants, has led to a postulated kinetic mechanism which proceeds through a substituted enzyme. This agrees with the earlier conclusions of Garces and Cleland [Biochemistry 1969; 8:633-640] who characterized a reaction between the magnesium complexes of the adenine and uridine nucleotides. An advantage of using thymidine nucleotides as reactants is that they permit accurate, rapid and continuous assays of the enzymatic activity in coupled-enzymatic tests. Through measurements of the initial velocities and product inhibition studies, the Michaelis constants, maximum velocities, and inhibition constants could be evaluated for the individual substrates. Competitive substrate inhibition was encountered at relatively high substrate concentrations, which also permitted an evaluation of their ability to act as 'dead-end' inhibitors. The Michaelis constants for the 3'-azido-3'-deoxythymidine (AzT) analogues were also evaluated and, although these values were only somewhat higher than those of their natural substrates, the Km's for the adenine nucleotides as paired substrates were lower and the Vmax's were drastically reduced. The pharmacological implications of these observations are touched upon and extrapolated to the cases where therapeutic doses of AzT may be employed.

A semi-automated neutral red based chemosensitivity assay for drug screening

A semi-automated colorimetric chemosensitivity assay was developed. The assay utilizes the vital stain neutral red for the rapid screening of potential anticancer agents using solid tumor cell lines. The cell lines used in this assay and presented in this report are CX-1 colon adenocarcinoma and A549 lung carcinoma. The assay, performed in 96 well tissue culture plates, allows for short drug exposure times (3 hrs.) followed by quantitation of cell number (neutral red absorbance) following four cell doubling times. Cell number directly correlated with absorbance of eluted neutral red at 540 nm. However, optimal amounts of dye and staining times varied between cell lines. IC50 concentrations (for inhibition of cell growth) determined using this assay were in good agreement with results from clonogenic assays using similar drug treatment conditions. The assay technique was determined to be capable of detecting antineoplastic compounds operating by a wide variety of mechanisms.

Long distance travel for routine elective surgery: questionnaire survey of patients' attitudes

OBJECTIVE

To carry out an audit and assess the acceptability of long distance travel to patients on a lengthy surgical waiting list.

DESIGN

Audit and questionnaire survey.

SETTING

Military hospital in Wiltshire.

PATIENTS

116 Patients on a general surgical waiting list at Leighton Hospital near Crewe.

INTERVENTIONS

Preselection for medical fitness at a waiting list review clinic.

RESULTS

Roughly half of patients offered the facility of travelling 120 miles (190 km) for their routine elective operation at the health authority's expense accepted. The average waiting list time declared by the patients who travelled was 28 months, and 13 patients stated that their condition prevented them from working. Only four patients regretted their decision to participate in the scheme. Lack of visitors did not cause undue concern.

CONCLUSIONS

Some patients did not agree to travel for their operation but almost all of those who did so found the scheme satisfactory. Some minor problems were encountered but these could probably be overcome by ensuring use of appropriate transport, extending the postoperative stay when necessary, and more careful selection of patients for an anaesthetic. For efficient use of theatre time in such schemes it is crucial that the operating consultant surgeon should be in charge of case selection.

Survey of general practitioners' opinions on the role of radiology in patients with low back pain

Ninety general practitioners responded to a questionnaire about the role of radiology in patients with low back pain. Their clinical indications for requesting radiographs were mostly in agreement with the opinions of radiologists, but nearly 80% requested investigations for their own or patients' reassurance. Understanding of the terms used by radiologists was good, although 25% thought that acute disc prolapse could be demonstrated on plain films. Previous training in radiology did not seem to influence knowledge. When general practitioners understood radiological terms they had clear therapeutic and specialist referral preferences. Poorly understood terms and those with which they were familiar but unclear about the implications for management were also identified.

Effects of age on cutaneous circulatory response to direct heat on the forearm

To investigate the effects of age on the response of skin blood flow in the forearm to direct heat, three groups of 20 male subjects each--young (20-39 yr); middle-aged (40-59 yr) and older (60-79 yr)--consented to have skin blood flow measured in the forearm by a TSI Model 403 laser Doppler flowmeter. This instrument detects changes in red blood cell velocity (LDV) in flow-active vessels and the volume of red blood cells flowing through these vessels (LDO). With the forearm in a 30 degrees C water bath there were no significant between-group differences in LDV or LDO. Elevating bath temperature to 35 degrees C elicited a significant increase in LDO in all three groups, but LDV did not significantly change. Increasing temperature to 40 degrees C elicited significant increases in both LDO and LDV with the former being of greater magnitude. At this temperature LDV values in both the middle-aged and older groups were significantly lower than those of the young subjects. Expressing the data during heating as percent change from 30 degrees C showed a significantly lower volume (LDO) response in the older group at 35 and 40 degrees C and a significantly lower LDV response at 40 degrees C for both the middle-aged and older subjects in comparison to the young group. It is concluded that aging decreases the response of cutaneous blood flow in the forearm to the direct effects of heat.(ABSTRACT TRUNCATED AT 250 WORDS)

Morpheus: a conformation-activity relationships and receptor modeling package

Our molecular modeling software package, MORPHEUS, allows the study of the interactions between biologically active molecules and their receptors. The package is capable of exploring the multidimensional conformational space accessible to each molecule of the data set under study. By specifying distance constraints or hypothetical receptor binding points, the package is able to filter the biologically accessible conformations of each active compound and deduce a three-dimensional model of the binding sites consistent with the properties of the agonists (or antagonists) under scrutiny. The electrostatic potentials in the environment of a putative binding site can also be investigated using the MORPHEUS package. The molecular modeling module CRYS-X, which is written in FORTRAN 77 for IBM PC machines, is capable of building, displaying and manipulating molecules.

Bitewing radiographs of children taken with and without a film-holding device

To help minimize radiation exposure, all dental radiographs must yield maximum diagnostic information. Film-holding devices have been recommended as a means of improving the diagnostic yield. Our study compared the diagnostic quality of bitewing radiographs of children taken with and without the aid of a film-holding device. 1014 bitewing radiographs (sizes 0, 1, 2) were taken of 338 children (aged 5-11 years) by senior dental students. Bitewing tabs were used for 554 radiographs and a film-holding device for the remainder. Diagnostic quality was calculated for each radiograph by dividing the number of non-overlapped contacts by the total number present. Both overall mean diagnostic yield and mean diagnostic yield for each size of film were found not to be significantly improved by use of the film-holding device. Position of overlapped contacts on each size of film was not equally distributed (P less than or equal to 0.01) among the contacts present. For size 0 and 1 films, overlap was most frequent between the maxillary first and second primary molars and for size 2 films between the maxillary first permanent molar and second primary molar/second bicuspid.

Bifurcation of scattering orders in degenerate four-wave mixing

Novel bifurcating scattering orders are predicted for the Raman-Nath regime of degenerate four-wave mixing in a medium that displays optical bistability due to increasing absorption.

Pyridoxal isonicotinoyl hydrazone and analogues. Study of their stability in acidic, neutral and basic aqueous solutions by ultraviolet-visible spectrophotometry

The ultraviolet-visible absorption spectra of the orally effective iron chelator, pyridoxal isonicotinoly hydrazone (PIH), and three analogues, pyridoxal benzoyl hydrazone (PBH), pyridoxal p-methoxybenzoyl hydrazone (PpMBH) and pyridoxal m-fluorobenzoyl hydrazone (PmFBH) have been measured in aqueous solution with various concentrations of added acid or alkali. Assignment of absorption bands to various molecular species in equilibrium in aqueous solution is made by reference to their acid ionisation constants. All four hydrazones were stable at physiologial pH, but hydrolysed in strongly acidic and basic solutions, resulting in the liberation of pyridoxal and the acid hydrazide. In acidic solutions this resulted in a dramatic decrease in the intensity of absorption at wavelengths of 225 nm and above 300 nm, allowing a quantitative estimate of the degree of acid-catalysed hydrolysis of the ligands. These results indicate that for oral administration the chelator should be administered with calcium carbonate or provided with an enteric coating to minimise acid-catalysed hydrolysis in the stomach. At high pH, base-catalysed hydrolysis occurred, resulting in a decrease in the absorption at a wavelength of 387 nm.

Differential neutrophil activation before and after endotoxin infusion in enterally versus parenterally fed volunteers

This study was done to determine whether or not increased susceptibility to infection seen in enterally versus parenterally fed patients was caused by altered neutrophil (PMN) responsiveness. To determine the differential effects of route of feeding on human PMN activation, plasma C3a levels, circulating PMN counts, PMN migration to leukotriene B4 (LTB4), the peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP) and zymosan activated serum (ZAS) and generation of LTB4 were assayed before and after and infusion of endotoxin. Nine normal volunteers were enterally (n=4) or parenterally (n=5) fed a diet sufficient to maintain body weight for seven days prior to a standard challenge of endotoxin. Samples were taken prior to the infusion and hourly thereafter for six hours. Prior to the injection of endotoxin, significant differences were seen in the two feeding groups. Plasma C3a levels, absolute circulating PMN counts and chemotaxis to LTB4 were all significantly (p less than 0.02) elevated in the enterally fed group. Generation of LTB4 was higher in the intravenously fed group at base line than the orally fed group (p less than 0.05). Plasma C3a levels rose in the enterally fed group, but not in the intravenously fed group, at two hours after infusion. Neutrophil counts rose in both feeding groups after endotoxin infusion; but the change in percentage was greater in the enterally fed group than in the intravenously fed group. Chemotaxis to FMLP and ZAS was not different during the study and did not differ between the two feeding can have significant impact on neutrophil function and that parenteral nutrition may impair host responsiveness.

Effect of pyridoxal isonicotinoyl hydrazone and other hydrazones on iron release from macrophages, reticulocytes and hepatocytes

A model consisting of 59Fe-labelled macrophages was developed for screening potential iron-chelating drugs. Mouse peritoneal macrophages, induced by previous intraperitoneal injections of 3% thioglycollate, were labelled in vitro by their exposure to immune complexes of 59Fe-transferrin-antitransferrin antibody. Optimal conditions for macrophage labelling and subsequent 59Fe release were established. Sixty-two aromatic hydrazones, the majority of which had iron binding structures similar to pyridoxal isonicotinoyl hydrazone, were synthesized by condensation of aromatic aldehydes (pyridoxal, salicylaldehyde, 2-hydroxy-1-naphthylaldehyde and 2-furaldehyde) with various acid hydrazides prepared by systematic substitutions on the benzene ring. These compounds were examined for their potential to stimulate 59Fe release from 59Fe-labelled macrophages and also from reticulocytes and hepatocytes loaded with non-heme 59Fe. The majority of hydrazones derived from pyridoxal, salicylaldehyde and 2-hydroxy-1-naphthylaldehyde seemed to be equally effective in both the macrophage and reticulocyte testing systems. However, the pyridoxal hydrazones were much more active in hepatocytes than the other groups of hydrazones. Several compounds proved to be very potent in mobilizing 59Fe. These included hydrazones derived from 2-hydroxy-1-naphthylaldehyde and benzoic acid hydrazide, p-hydroxybenzoic acid hydrazide, 2-thiophenecarboxylic acid hydrazide, and also pyridoxal benzoyl hydrazone, pyridoxal m-fluorobenzoyl hydrazone and pyridoxal 2-thiophenecarboxyl hydrazone.

Effects of gravity on regional and capillary blood flows in the human toe

The purpose of this study was to investigate the relative effects of gravity on capillary and regional blood flows in human extremities. Eighteen male subjects 20 to 40 years of age consented to have capillary blood cell velocity (CBV) measured in nailfold vessels of the large toe via video densitometry, and to have total blood flow (TBF) to the toe measured via plethysmography. These measurements were made first with the foot at heart level (HL), then after the foot had been lowered an average of 56 cm below the heart (BH). In the HL position CBV and TBF averaged respectively 0.26 mm/sec and 2.0 ml/min/100 ml. Lowering the foot elicited a decrease in CBV in all vessels studied (P less than or equal to 0.001). Average CBV in the BH position was 0.11 mm/sec. By contrast TBF on the average increased to 2.9 ml/min/100 ml in the BH position (P less than or equal to 0.05). However, this was not a consistent finding since both increases and decreases in TBF were observed among the individual subjects. These results indicate that the immediate precapillary vessels in the cutaneous circulation of the toe will consistently vasoconstrict when the foot is placed in a dependent position. However, the net effect on vessels governing regional flow in this area, e.g., A-V shunts, appears to result from a competition between dilator and constrictor influences. The overall result of these adjustments is that during orthostasis blood is shifted away from the superficial capillaries of the lower extremities. The relevance of this to blood-tissue fluid balance is discussed.

Effect of chronically elevated androgen or estrogen on the glucose tolerance test and insulin response in female rhesus monkeys

Insulin concentrations, in response to an intravenous glucose bolus after a 24-hour fast, have been studied in female rhesus monkeys in which the circulating levels of androstenedione and testosterone or estrone and estradiol have been increased for as long as 4 1/2 years. No significant differences were observed in the basal insulin or C-peptide concentrations in the androgen or estrogen-treated animals compared with each other or with normal cycling, nontreated control animals. The insulin and C-peptide responses to intravenous glucose were similar in control and androgen-treated monkeys. Compared with both the control and androgen-treated monkeys, the responses of the estrogen-treated monkeys tended to be lower but were not significantly different. The glucose disappearance rate after the intravenous glucose bolus was not significantly different in androgen and control monkeys but was significantly slower during the initial 30 minutes in the estrogen-treated monkeys compared with both the control and androgen-treated monkeys. These studies suggest that chronically elevated androgen levels in the mature female subhuman primate do not lead to insulin resistance or overt glucose intolerance.

Fish oil increases peripheral capillary blood cell velocity in humans

Fish oils containing n-3 fatty acids have been shown in humans to decrease platelet aggregation in vitro, lower plasma triglycerides, and to increase bleeding time. The in vivo effects of fish oils on microcirculatory blood flow in humans has not been studied to date. Twenty-one male subjects were randomly assigned to either olive oil (n = 10) or fish oil (n = 11) supplemented groups to determine the effects of these oils on capillary blood flow velocity (CBV) in the nailfold area. The subjects were given the oils for three weeks (1.5 g oil/10 kg b.wt./day) in a single blind study design. In addition to CBV plasma lipid profiles, blood viscosity, blood pressure and platelet and erythrocyte fatty acids were also determined prior to and after the dietary intervention. Fish oil supplementation significantly increased CBV, by 1.75-fold (0.144 +/- 0.069 to 0.253 +/- 0.147 mm/s). The olive oil group remained unchanged. Increased levels of n-3 fatty acids were noted in platelets and erythrocytes of the fish compared to olive oil-supplemented groups. Blood viscosity was unaltered in both groups, however, blood pressure in the olive oil supplemented group was significantly decreased. Plasma triglycerides were significantly decreased in the fish oil supplemented group. These observations suggest that increases in CBV after fish oil supplementation are due to changes in vascular tone and not to alterations in blood pressure or blood viscosity.

Gaze-evoked tinnitus

Two patients developed gaze-evoked tinnitus in the year following removal of a cerebellopontine angle mass. The eighth nerve was transected in both cases. The noise was present with saccades, pursuit, and vestibuloocular eye movements. We postulate the tinnitus was due to an abnormal interaction between the vestibular nucleus and the cochlear nucleus, possibly secondary to neural sprouting.

Prospective evaluation of a risk scoring system for predicting preterm delivery in black inner city women

Nine percent of United States births are preterm. The ability to efficiently identify women destined to deliver before term would enable obstetricians to initiate early intervention. The Papiernik-Creasy risk scoring system is being extensively applied for this purpose, without prospective validation in this country. We evaluated prospectively its ability to predict high risk women in a black inner city population, when applied once early in pregnancy. The system, based on social, past medical, and current pregnancy problems, failed to identify at-risk patients. Adjusting the score cutoff and reweighting factors with discriminate analysis did not improve the predictive value. Analysis of an additional 60 social, demographic, and medical factors failed to produce a useful alternative risk assessment tool. We suggest that risk scoring systems such as these may not be helpful in socioeconomically at-risk populations.

Effects of tobacco smoke inhalation on capillary blood flow in human skin

To measure the effects of tobacco smoke inhalation on capillary blood flow in human skin, 20 female tobacco smokers consented to smoke three cigarettes with nicotine levels of 0.50, 0.98, and 1.90 mg per cigarette, each on a separate occasion. Measurements of blood flow velocity and vascular diameter were made along the venous limb of capillaries within the nailfold skin of the third finger via videomicroscopy before and for 5 min after the smoking of each cigarette. Capillary blood flow (CBF) was calculated as a product of capillary cross-sectional area and flow velocity. Resting pre-smoke CBF for all experiments combined averaged 4.7 X 10(4) mu 3/sec. All three cigarettes elicited a significant reduction in CBF with the maximal effect within the first 2 min of the post-smoke period (p less than or equal to .05). Respective CBF values during this time averaged 3.6, 3.4, and 2.7 mu 3/sec for the low-, medium-, and high-nicotine cigarettes. Although the data suggested a downward trend in CBF with increasing nicotine levels, the post-smoke values were not significantly different among the three cigarettes. It is concluded that acute tobacco smoke inhalation reduces CBF in human skin, but the effect is not related to the nicotine content of the cigarettes. The changes in cutaneous CBF observed with tobacco smoking are less compared to reported effects of smoke inhalation on total digital blood flow.

Using a business plan to develop a freestanding radiology center

Physicians, hospitals and investors are closely scrutinizing the market for freestanding diagnostic and therapeutic centers. Developing a center's business plan can be a critical first step for physicians to gauge the profitability of a new project. Elements of a plan include: volume projections, referral issues, regulatory environment, financial and performance indicators, accountability, time frames and a marketing plan.

Relative effects of static muscle contraction on digital artery and nailfold capillary blood flow velocities

Previous studies have shown that a decrease in blood flow to the finger is not necessarily accompanied by a corresponding change of blood flow in nailfold capillaries. The purpose of this study was to determine if nailfold capillary blood flow remains relatively stable during a decrease in finger blood flow induced by muscle contractions. Four male subjects 20 to 30 years of age exerted 2-min periods of static calf muscle contraction at levels of 7.5, 15, 30, and 45% of their maximum voluntary contractile force (MVC) while systemic blood pressure (BP), and flow velocities in the digital artery (VEL-A) and nailfold capillaries (VEL-C) were measured by, respectively, Doppler ultrasound and video densitometry. Each subject repeated the series five times. There was a significant linear decrease in VEL-A with increasing force of contraction for each subject individually (P less than or equal to 0.009) and for the group as a whole (P less than or equal to 0.0001); whereas VEL-C did not significantly change during muscle contraction. These results indicate that the initial cutaneous constrictor response in the finger during the onset of leg muscle exercise is not reflected to the nailfold capillaries.

Medical school education in hypertension management: a national survey

Results of a survey of 90 medical schools in 44 states indicate that only 11 had specific hypertension sections, and that after completion of four years of medical school, students had received only 18 hours of instruction in the management of hypertension. Undergraduate students spent only an average of 1.5 weeks in clinics specifically designated for the treatment of hypertension, and small numbers of students were involved in each school at any one time. Specific instruction during residency training was also minimal. Even when ward round and general medical clinic teaching hours are included, instruction in the management of hypertension is limited for a disease that is the most common chronic illness in the United States and accounts for over 5 percent of all physician visits by adults. An increased emphasis should be placed on training for the management of hypertension within the undergraduate curriculum and within the existing general medical and hypertension clinics.

Effects of ischemia on capillary density and flow velocity in nailfolds of human toes

The purpose of this study was to investigate reactive hyperemia in the capillary network of human skin in terms of the flow per capillary and the density of flow-active capillaries. Seventeen male subjects 20 to 40 years of age were seated with their right foot placed on the stage of a Leitz epi-ilumination microscope such that the nailfold capillary field in their large toes could be viewed. These vessels were video taped while flow velocity in the right posterior tibial artery was recorded via Doppler ultrasound at rest, then following a 45-sec period of arterial occlusion to the foot. Subsequent to experimentation flow velocity in single nailfold capillaries was measured via video densitometry and the number of flow-active capillaries in the field of view were counted. Following the release of arterial occlusion arterial flow velocity increased 142% above rest, the velocity in single capillaries increased by 54%, and the density of flow-active capillaries, as identified by the presence of red cells, decreased by 37%. The fact that capillary flow velocity increased to a lesser degree than arterial velocity during reactive hyperemia vis-a-vis a decrease in the number of flow-active capillaries indicates that ischemia to the foot elicits a smaller dilatory effect in vascular elements controlling blood flow to the superficial cutaneous region of the toe as compared to other regional vascular networks.

The effect of chronic and acyclic elevation of circulating androstenedione or estrone concentrations on ovarian function in the rhesus monkey

The concept that chronically elevated blood androstenedione concentrations increase the incidence of anovulation in the primate and that acyclic elevated basal blood androgen and/or estrogen concentrations cause abnormal gonadotropin secretion was studied. Regularly menstruating female rhesus monkeys were implanted sc with Silastic tubing filled with androstenedione or estrone and compared with controls. Androstenedione implants increased the serum androstenedione concentrations from 1.6 +/- 0.1 (SE) ng/ml to 6.30 +/- 0.27 ng/ml. By peripheral conversion the testosterone concentration increased from control values of 279 +/- 10 (SE) pg/ml to 1280 +/- 41 pg/ml. The testosterone concentration in the estrone-treated monkeys was 247 +/- 9.7 pg/ml. The estrone concentrations were: controls, 63.2 +/- 3.1 (SE) pg/ml; androstenedione-treated monkeys, 63.2 +/- 3.1 pg/ml; and estrone-treated animals, 150 +/- 5.3 pg/ml. The corresponding estradiol concentrations were: control animals, 35.1 +/- 2.1 (SE) pg/ml; androstenedione animals, 30.9 +/- 1.8 pg/ml; and estrone-treated monkeys, 65.7 +/- 3.9 pg/ml. There was no difference in the morning serum cortisol concentrations between any of the three groups or between ovulatory or anovulatory months. The chronic elevation of either androstenedione or estrone caused an increased incidence of anovulation compared with the controls. Increased estrogen concentrations caused increased anovulation during both summer and winter months; however, increased androgen concentrations caused increased anovulation only during the summer months. However, LH concentrations were unaffected in either group but were lower during anovulation months in all three groups. An LH or FSH surge followed an estradiol bolus in three of four control animals and four of six androstenedione-treated but none of the estrone-treated monkeys. Histological examination of ovarian biopsies demonstrated thickening of the tunica albuginea ovarii in androgen-treated ovaries and an apparent increased number of atretic follicles. Corpora lutea were absent in the ovaries of the estrogen-treated monkeys, but otherwise these ovaries were similar to those of controls. It is concluded that chronic acyclic elevation of blood androstenedione (and resultant testosterone) increases seasonal anovulation in the rhesus monkey. Increased blood estrone (and resultant estradiol) leads to almost complete anovulation throughout the year and renders the central nervous system-pituitary axis insensitive to positive feedback effect of estradiol. Neither treatment caused an increase in basal LH concentrations.(ABSTRACT TRUNCATED AT 400 WORDS)

Amniostat FLM: a new technique for detection of phosphatidylglycerol in amniotic fluid

Amniostat-FLM (AFLM) is an immunologic semi-quantitative slide agglutination test for determining the presence of phosphatidylglycerol (PG) in amniotic fluid. We analyzed 178 samples for the presence of PG by both AFLM and our standard thin-layer chromatographic technique (TLC). Both tests agreed in 135 of 178 cases. All fluids with a mature AFLM had PG detected by TLC assay. All of the 43 discordant samples were classified as immature by AFLM although PG was present by TLC. Among the 151 patients who delivered within 72 hours of amniocentesis, 17 cases of respiratory distress syndrome (RDS) occurred. All were correctly predicted by immature tests. However, an immature AFLM was associated with RDS in only 21% of cases (11/53) while 37% of cases (17/46) with an immature TLC test resulted in neonates with RDS. We conclude that the AFLM is a very simple, rapid, and sensitive test for identifying infants who will develop RDS but is less specific than the TLC assay. Though a mature AFLM will predict fetal pulmonary maturity, an immature result should be confirmed by thin-layer chromatographic analysis.

Can preterm deliveries be prevented?

Our hospital serves poor, inner-city women who have a 17% preterm delivery rate. Middle-class women in San Francisco at high risk for preterm delivery have benefited from an antepartum program which emphasized patient education and close follow-up. Using a controlled, randomized design, we are investigating the impact of similar interventions. Patients determined to be at high risk before 18 weeks' gestation on the basis of the Creasy system are randomly assigned to the Preterm Labor Prevention Clinic or serve as high-risk controls. Sixty-four women assigned to the Preterm Labor Prevention Clinic and 68 high-risk control women have been delivered of their infants. No significant differences were noted for the percentages of preterm infants, mean gestational age, or birth weight. Preterm rupture of the membranes accounted for 40% of preterm deliveries in all high-risk patients. Thirty percent of preterm births were indicated for maternal or fetal reasons. The remaining 30% represented failure of tocolytic therapy.

Male violence toward females: victim and aggressor variables

The present study focused on the effects of two variables that have been proposed as determinants of male violence toward female targets in American society. One target variable, verbal attack, and one aggressor variable, masculine performance, were manipulated. Forty male research participants competed in a reaction-time task with a female confederate who had previously criticized them or remained silent when the males' performance on a physical strength task appeared to be average or considerably below the norms for male performance. The significant interaction between the two variables indicated that inhibitions against harming females were reduced when the male performed poorly on a masculine task in the presence of a female who criticized his performance. Results are discussed in terms of their relevance to control and understanding of male-to-female aggression in the natural ecology.

Measurement of portal and hepatic blood flows using a modified method for surgical placement of catheters in the major splanchnic vessels of sheep

A modified catheterization and para-aminohippurate dye dilution technique was used to measure portal and hepatic blood flows in sheep. Blood flows (mean +/- 1SD) for 7 healthy sheep were 1.54 +/- 0.71 L/min and 1.98 +/- 0.75 L/min for portal and hepatic flows, respectively. Blood flow measurement was facilitated when dye injection rates produced blood para-aminohippurate acid concentrations greater than 15 mg/L. Uniform mixing of dye with blood was confirmed in 1 sheep with 2 portal vein catheters. Surgery to place the catheters was facilitated by using a ventral para-costal approach. Blood gas analysis was useful in confirming the placement of the catheters. Useful catheter life in this experiment was 41 days, which was longer than in previous reports. Treating the catheters with an organo-silane preparation, protecting the catheters against dislodgement, and use of a belly bandage to minimize damage to the external parts of the catheter may have prolonged catheter life in this experiment.

Comparison of resting capillary flow dynamics in the finger and toe nailfolds

The purpose of this study was to compare capillary dynamics in the nailfold regions of the human toes and fingers. Capillary blood flow velocity (VEL), vessel diameter, the total number of capillaries and the number of capillaries with active flow per mm2 of tissue were measured in the toe nailfold region of 17 and in the finger nailfolds of 15 male subjects 20 to 40 years of age. All measurements were made in the rest state at a skin temperature of 32 degrees C. Group averages were: (Formula: see text). These results demonstrate that compared to the finger the nailfold capillaries in the toe have a lower blood flow per vessel but a much higher capillary density. The combination of these factors indicates that total capillary blood flow is higher in the toe nailfold system.

Hepatic and extrahepatic lactate metabolism in sheep: effects of lactate loading and pH

Hepatic lactate metabolism was studied in five sheep receiving infusions of either lactic acid or sodium lactate using an arteriovenous difference technique. Hepatic uptake of lactate was a saturable process with second order (Michaelis-Menten) kinetics. Although lactic acid infusion decreased blood pH, hepatic saturation of lactate uptake occurred before changes in pH could influence hepatic lactate metabolism. The Vmax for hepatic lactate metabolism is 5.72 mmol X kg-0.75 X h-1 and the Km 3.06 mmol/l. These findings have therapeutic relevance. In acidosis, the hepatic response to therapeutic administration of sodium lactate during fluid therapy will be variable. If plasma lactate is low, lactated fluids may increase hepatic uptake and produce an alkalizing effect. If plasma lactate is already high, hepatic lactate metabolism is nearly saturated, and additional lactate will not produce a hepatic alkalizing response. Extrahepatic tissues switch from lactate production to lactate utilization under conditions of lactate loading. They remove more lactate than liver at high plasma lactate concentrations. Muscle may be important in lactate removal in certain types of exercise.

Analysis of human sperm function following exposure to the ionophore A23187. Comparison of normospermic and oligozoospermic men

Time exposure photomicrography and interspecific in vitro fertilization techniques have been used to compare the responses to the divalent cation ionophore A23187 of spermatozoa from normal fertile and oligozoospermic men. The fertilizing capacity of spermatozoa from the fertile controls produced a bell-shaped dose response curve when assessed in the presence of ionophore. The optimal responses occurred in the presence of 50 and 100 microM A23187. At this concentration, a mean penetration rate of about 75%, in association with multiple polyspermy, was observed without significant changes in motility patterns. At higher doses of A23187, there was a decline in fertilization rates, an independent reduction in sperm motility, and a significant decrease in the amplitude of lateral sperm head displacement. In contrast to the fertile controls, spermatozoa recovered from patients with oligozoospermia failed to exhibit a significant change in their fertilizing potential following exposure to A23187. Calculations based on the Poisson distribution theory indicated that this lack of responsiveness was not related to any differences in the motility of the spermatozoa from the oligozoospermic patients compared to the controls. These results suggest that calcium ionophores may be of value in providing a rapid and sensitive indicator of the functional competence of human spermatozoa, which circumvents problems concerning the rate and efficiency of sperm capacitation encountered with conventional protocols.

Tissue sites of aromatization in the female rhesus monkey

Nine female rhesus monkeys (four in the follicular and five in the luteal phases of their cycles) had catheters implanted and were infused iv with [7-3H]androstenedione (A) and [4-14C]estrone (E1) for 4 h. Blood samples were drawn at intervals from the hepatic, renal, jugular, uterine, and brachial veins and the femoral artery. The samples were analyzed for radioactivity as A and E1. The mean +/- SE MCRs for A and E1 were 280 +/- 40 and 270 +/- 30 liters/day, respectively. The mean extractions across the liver measured in six of the monkeys were 0.83 +/- 0.03 for A and 0.71 +/- 0.06 for E1. The percentage of A entering each tissue, which was measured as E1 leaving the tissue (pA,E1AV), was 0.20 +/- 0.10 for splanchnic, 0.21 +/- 0.11 for renal, 0.46 +/- 0.21 for jugular, 2.36 +/- 1.27 for arm, and 0.35 +/- 0.10 for uterine veins. Because of the sampling technique, the value for the uterus may be a reflection of ovarian blood admixture with uterine blood. There were no apparent differences in tissue aromatization between values in the follicular and luteal phases of the cycle. The overall mean value for the percentage of A infused and measured as E1 in arterial blood (pA,E1BB) was 1.01 +/- 0.38%. Using previously reported tissue blood flow, we calculate that the contributions to the overall aromatization rate of tissues drained by the brachial, renal, jugular, hepatic, and uterine veins are 23%, 5%, 5%, 4%, and 0.2%, respectively. Thus, the splanchnic tissue is a minor site for extraglandular aromatization of androgens in the rhesus monkey. An important site appears to be the arm, which reflects aromatization in adipose tissue, muscle, skin, and supporting structures.

Facility report: Holston Valley Hospital and Medical Center

Part of an expanding institution, the respiratory services department at Holston Valley Hospital and Medical Center, Kingsport, Tenn, performs an impressive number and variety of procedures. Twelve-hour shifts and a new school of respiratory therapy are unique aspects.

Genetic bisalbuminaemia occurring together with myeloma

Bisalbuminaemia occurring together with paraproteinaemia in a case of proven myelomatosis is described. The albumin variant was investigated by dye-binding, electrophoresis at pH 5·0, 6·8, and 8·6, and by relative mobility studies compared with known genetically inherited variants. The present variant was indistinguishable from the previously described Pollibauer type.

The dilemma of essentiality in homosexual theory

A close examination of the literature on homosexuality reveals a long history of definitional crises in which the central consideration has been the maintenance of a belief in homosexuality as a state of being. This paper asks what, if anything, can be considered essential to the homosexual category. To answer this question, various approaches to homosexuality in the literature have been examined: as a general state of being (the person), as a state of desire (sexual orientation), as a form of behavior (sexual acts), and, more recently, as a personal identification (sexual identity). In addition, the interrelationships of these categorizations are explored.

Nonketotic hypoglycemia: an early indicator of systemic carnitine deficiency

In systemic carnitine deficiency, an early phase of nonketotic hypoglycemia and liver dysfunction may precede a late phase of encephalopathy and myopathy. We studied two children with recurrent episodes of nonketotic hypoglycemia who were found to have systemic carnitine deficiency without myopathy or encephalopathy. Early institution of appropriate therapy prevented the onset of late debilitating complications in one patient, whereas therapeutic noncompliance in the other patient led to an episode of encephalopathy and myopathy. Metabolic studies indicated that decreased availability of alanine may be a factor in the genesis of hypoglycemia; concurrent depletion of cerebral glucose, ketones, and glycogen may be the cause of the encephalopathy.