Human immunodeficiency virus-1 seroprevalence among parturients in Los Angeles County public hospitals

To estimate the prevalence of human immunodeficiency virus type 1 (HIV-1) among parturients in an area with a high cumulative incidence of AIDS, an HIV seroprevalence study was conducted in 1988 in Los Angeles County. Test results were available from 8485 (86.1%) of the 9860 women delivering at four public hospitals. The test results were linked to demographic and medical information available from routinely collected delivery records. Three specimens were HIV-positive, for a seroprevalence of 3.5 per 10,000. The seropositive women were all Latina. The prevalence of HIV among women delivering at all hospitals in Los Angeles County has been shown to be relatively low compared with that of other metropolitan areas with a high number of AIDS cases, such as New York city, but appears to be even lower among women delivering at public hospitals during this time period. This low prevalence is attributed to the predominance of Latinas, who may have lower levels of infection, among public hospital parturients. The relatively low prevalence of HIV among injection drug users in Los Angeles County may contribute to the overall lower prevalence among women in Los Angeles County compared with those in New York city. This study supplements county-specific data obtained from statewide blinded neonatal testing by providing details on HIV seroprevalence among the catchment populations of public hospitals in Los Angeles County.

Charge movement and SR calcium release in frog skeletal muscle can be related by a Hodgkin-Huxley model with four gating particles

Charge movement currents (IQ) and calcium transients (delta[Ca2+]) were measured simultaneously in frog skeletal muscle fibers, voltage clamped in a double vaseline gap chamber, using Antipyrylazo III as the calcium indicator. The rate of release of calcium from the SR (Rrel) was calculated from the calcium transients using the removal model of Melzer, W., E. Rios, and M. F. Schneider (1987. Biophys. J. 51:849-863.). IQ and delta [Ca2+] were calculated for 100 ms depolarizing test pulses to membrane potentials from -30 to +20 mV. To eliminate an inactivating component of Rrel, each test pulse was preceded by a large, fixed prepulse to +20 mV. The resulting Rrel records, which represent the noninactivating component of Rrel, were compared with integral of IQdt.(Q), the total charge that moves. The voltage dependence of the steady state Rrel was steeper then that of Q and shifted to the right. During depolarization, the Rrel waveform was similar to that of Q but was delayed by several ms, while, during repolarization, Rrel preceded Q. All of these results could be explained with a Hodgkin-Huxley type model for E-C coupling in which four voltage sensors in the t-tubule membrane which give rise to IQ must all be in their activating positions for the calcium release channel in the SR membrane to open. his model is consistent with the structural architecture of the triadic junction in which four dihydropyridine receptors (the voltage sensors for E-C coupling) in the t-tubule membrane are closely associated with each ryanodine receptor(the calcium release channel) in the SR membrane [Block, B. A., T. Imagawa, K. P. Campbell, and C. Franzini-Armstrong. 1988. J.Cell. Biol. 107:2587-2600.]). Some aspects of this work have appeared in abstract form (Simon, B. J., and D. Hill. 1991. Biophys. J.59:64a. ([Abstr.]).

Evaluation of TRISS as a means of selecting trauma deaths for clinical peer review

This study was carried out to evaluate the predictive power of a mathematical model called TRISS in identifying avoidable trauma deaths when compared with peer review (PR). The subjects studied comprised the 24 deaths that occurred among 81 severely injured patients (Injury Severity Score greater than or equal to 16) admitted to a trauma unit over a 1 year period. Sixteen patients who had a greater than 50% probability of survival (Ps) calculated by TRISS died. Peer review concluded that five of those were potentially avoidable deaths. Eight deaths occurred in patients with a Ps less than 50%. Peer review regarded those eight as inevitable deaths. The data, when analysed, showed TRISS to have a 100% sensitivity, 42% specificity, 31% positive predictive value and a negative predictive value of 100% when compared with peer review. It is concluded that TRISS tends to over-estimate potentially avoidable death, especially in patients with severe head injury. However it is a good audit filter as it reliably excludes inevitable death.

Two approaches to the axillary brachial plexus. Loss of resistance to saline or paraesthesia?

A new technique of cannulation of the axillary neurovascular sheath, using loss of resistance to saline, was evaluated and compared to the established technique of eliciting paraesthesiae with a short-bevelled needle. The cannulation technique produced a more reliable block of axillary, musculocutaneous and radial nerves, significantly fewer incomplete blocks and a lower incidence of accidental vessel puncture.

SCORPIO: a system of medical teaching

Reform in medical education is gaining momentum through the efforts of organizations such as the World Federation for Medical Education. Through the advocacy of such bodies, educational priorities have been redefined to widen the range of educational settings, upgrade evaluation systems and promote the training of teachers as educators. A system of medical teaching has been developed which addresses these issues. It is known by the acronym SCORPIO. The key elements of the system are that it is Structured, Clinical, Objective Referenced, Problem-based, Integrated and Organized. SCORPIO involves delivering a syllabus through a series of lecture-demonstrations at which students, teachers and patients gather at a defined area. Following a short introductory lecture, students rotate in small groups, through a series of teaching stations. These stations are structured to provide students with a problem-based, integrated learning experience. Assessment stations may be included before, during or after the teaching circuit. The teaching system has been formally evaluated over a period of time and now has an established place in the curriculum of this medical school.

Complementary value of traditional bedside teaching and structured clinical teaching in introductory surgical studies

A prospective randomized trial was conducted to see if student performance in a combined multiple choice and objective structured clinical examination was better following a period of structured clinical teaching compared with traditional bedside teaching. Student groups were crossed over in a second phase of the experiment to allow the two teaching techniques to be compared sequentially in the same group. There was no significant difference between the two teaching techniques as measured by performance in a criterion-referenced examination. The results of the study led to modification of the curriculum for third-year introductory surgical studies to incorporate both teaching strategies, which are regarded as complementary in value.

Acute aortic occlusion presenting with lower limb paralysis

In a two year period eight patients have presented with acute aortic occlusion and a poor outcome in seven. Initial failure to diagnose aortic occlusion, with a mean delay from presentation to diagnosis of 24 hours, was mainly responsible. All patients had varying degrees of paralysis on presentation which misled clinicians although other findings of acute ischaemia (pain, absent pulses, colour change and anaesthesia) were always present. Two patients were initially referred to a neurologist, another to a neurosurgeon, and the fourth to an orthopaedic surgeon. Even after diagnosis had been established, the need for urgent revascularization was not always recognized, the mean time from diagnosis to revascularization being 13 hours. Unnecessary aortography contributed to this delay in four patients. In two patients operative treatment was not undertaken while six were treated operatively by: aortic bifurcation graft (3), aortic thromboendarterectomy and femoropopliteal bypass (1), open aortic embolectomy (1) and bilateral femoral embolectomy (1). The causes of aortic occlusion were thrombosis of an atherosclerotic aorta (5), thrombosis of an aneurysm (2) and embolism (1). In the latter patient, the heparin induced thrombocytopenia syndrome (HITS) was primarily responsible. The outcomes in the eight patients were death (5), paraplegia (1), amputation (1), and uncomplicated recovery (1). The single patient who made an uncomplicated recovery had the shortest delay from presentation to revascularization of only 2 1/4 hours. Acute aortic occlusion rivals aortic rupture as a vascular emergency and demands immediate operative intervention.

Potential contribution of absorbed volatile fatty acids to whole-animal energy requirement in conscious swine

Chronic cannulas were placed in the hepatic portal vein, ileal vein, and carotid artery in seven crossbred growing gilts trained to consume once daily 1.2 kg of a 16% CP corn-soybean meal diet. Eleven days after surgery, each pig (37.4 kg BW) was placed in an open-circuit calorimeter and its cannulas were connected to a system for determining portal absorption of nutrients. The whole-animal heat production and net portal absorption of gut VFA were measured simultaneously for 12 h after the pig was fed 1.2 kg of feed. Plasma concentrations of VFA, including acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids, in portal and arterial samples were determined by gas chromatography after a cleanup by ion-exchange chromatography. The net portal absorption of VFA was calculated by multiplying the porto-arterial plasma concentration difference of the VFA by portal vein plasma flow. Plasma flow was estimated by the indicator-dilution technique using p-aminohippuric acid as the indicator. The energy value of absorbed VFA was the sum of products of each individual VFA multiplied by its corresponding value of the heat of combustion. The mean hourly energy value of absorbed VFA during the 12-h postprandial period was .65 +/- .03 kcal.h-1.kg BW-1. The mean hourly whole-animal heat production was 2.70 +/- .04 kcal.h-1.kg BW-1. Thus, in our 37.4-kg pigs, which were trained to consume 1.2 kg of a 16% CP corn-soybean meal diet once daily, the gut VFA absorbed into the portal vein could contribute 23.8 +/- 1.1% to whole-animal heat production if all of the absorbed VFA were combusted to CO2.

Comparing the yield of the standard Papanicolaou and endocervical brush smears

To compare the endocervical cell yield of the standard Papanicolaou smear and endocervical brush (Cytobrush) smear, cervical cytology smears using both techniques were obtained separately from each of 491 women between Aug 1, 1987, and Jan 31, 1990. The smear provided endocervical cells from 97% of the patients, while the Papanicolaou smear provided them from 64%. The brush was unsatisfactory (no endocervical cells) in 3% of the patients. In nine patients (2%) no endocervical cells were found on either specimen. In six patients (1%) the brush smear was unsatisfactory, while endocervical cells were found on the Papanicolaou smear. The study design precluded an adequate assessment of the sensitivity for detecting abnormal cells with the addition of the brush. The addition of an endocervical brush smear to the routine Papanicolaou smear appears to provide better sampling of the endocervical canal than does the standard Papanicolaou smear alone, using a cotton-tipped applicator.

Endoscopic management of gallstone pancreatitis

The use of minimally invasive techniques of removing gallstones, and the gall-bladder, is an attractive option for patients who may be severely ill with pancreatitis. We describe here a patient with gallstone pancreatitis who was managed completely by endoscopic techniques consisting of endoscopic retrograde cholangiopancreatography (ERCP) followed by laparoscopic cholecystectomy.

Effects of amiodarone administration during pregnancy in Fischer 344 rats

Amiodarone is a class III anti-arrhythmic compound that is iodinated, cationic and amphiphilic in nature. The clinical use of amiodarone may be associated with various side-effects, including pulmonary and hepatic toxicity. Use of this compound during pregnancy may therefore place the fetus at risk through in utero exposure. This study was designed to observe any gross developmental effects that may be caused by the administration of amiodarone to Fischer 344 rats during pregnancy, investigate the placental transfer of amiodarone and its principal metabolite, desethylamiodarone and determine the levels of amiodarone and desethylamiodarone in the maternal and newborn lung, liver and plasma. To conduct this study, 35 mg/kg of amiodarone was administered daily to pregnant rats for either the last 7 days of pregnancy, the last 14 days of pregnancy, or for the full 22 days of pregnancy. Drug treatment had no effect on the length of gestation or litter size. Maternal weight gain was decreased only when amiodarone was administered during the last 7 days of gestation. The birthweights of the offspring were decreased, however, crown to rump length was unaffected. Both amiodarone and desethylamiodarone accumulated in the offspring through placental transfer. The levels of both compounds were greater in maternal and newborn lung when compared to maternal and newborn liver, respectively. The maternal lung and liver concentrations of both compounds were significantly higher than the respective newborn concentrations. The newborn plasma concentrations of amiodarone and desethylamiodarone were significantly lower than maternal levels indicating that the placenta may not be totally permeable to the two drugs.

Effects of ractopamine on genetically obese and lean pigs

Twenty-eight genetically obese and 24 lean barrows (65.0 and 68.7 kg average BW, respectively) were allotted within genotype to a 16% CP corn-soybean meal basal diet or this basal diet + 20 ppm ractopamine (a phenethanolamine beta-adrenergic agonist) and allowed ad libitum access to feed for 48 d. Compared to lean pigs, obese pigs had lower ADG, gain to feed ratio, longissimus muscle area, predicted amount of muscle, and weights of trimmed loin and ham, ham lean, heart, spleen, kidney and gastrointestinal tract (P less than .05). Obese pigs also had shorter carcass but higher dressing percentage, backfat thickness, fat depth, fat area, untrimmed loin weight and fasting plasma urea N concentration (P less than .05). Dietary supplementation with 20 ppm ractopamine reduced daily feed intake and improved gain to feed ratio in both lean and obese pigs (P less than .05). Pigs fed ractopamine had shorter carcasses, less fat depth and fat area, smaller weights of stomach and colon plus rectum, but higher dressing percentages, longissimus muscle areas, weights of trimmed Boston butts, picnics and loins, ham lean and predicted amounts of muscle than pigs not fed ractopamine (P less than .05). Supplemental ractopamine had no effect on fasting plasma concentrations of urea N, nonesterified fatty acids, triglyceride or glucose (P greater than .05). No genotype x ractopamine interactions for the criteria described above were detected (P greater than .05). These results suggest that ractopamine will improve the efficiency of feed utilization and carcass leanness in swine with different propensities for body fat deposition.

Responses to cimaterol in genetically obese and lean pigs

Twenty-four genetically obese and 24 lean barrows were allotted within genotype to either a 16% CP corn-soybean meal basal diet, the basal + .69 ppm cimaterol or the basal + 1.38 ppm cimaterol. Pigs had ad libitum access to their diets from 59.3 kg to 104.5 kg body weight. No genotype x cimaterol interactions were detected (P greater than .05). Neither genotype nor cimaterol supplementation had any effect (P greater than .05) on average daily weight gain or gain-to-feed ratio. Compared with lean pigs, obese pigs had higher fasting plasma urea nitrogen (BUN), a smaller gastrointestinal tract and a greater dressing percentage with a shorter and fatter carcass (P less than .05). Cimaterol produced a higher fasting plasma BUN, a greater dressing percentage with a leaner carcass and a higher shear force value for loin chops (P less than .05). Cimaterol also tended (P less than .10) to increase heart weight. However, no difference was observed in these measurements between pigs fed .69 or 1.38 ppm cimaterol. In lean pigs fed the basal or .69 ppm cimaterol diet, there was no difference (P greater than .05) in the 8 to 24 h postprandial whole-animal heat production. Cimaterol effectively decreased fat deposition and increased lean accretion both in genetically obese and in lean pigs; there were no differential responses to cimaterol in pigs with different propensities to deposit body fat.

Oxygen consumption by portal vein-drained organs and by whole animal in conscious growing swine

A method was developed to measure simultaneously the O2 consumption (VO) by the whole animal and by the hepatic portal vein-drained organs (PVDO), including the gastrointestinal tract, spleen, and pancreas in conscious 3.5- to 4-month-old swine. The method was used to determine (i) the effect of feeding on hepatic portal vein blood flow rate (Qpv) and VO by PVDO and by the whole animal, and (ii) the significance of PVDO on the oxidative demand in the pig. Chronic cannulas were placed in the hepatic portal vein, carotid artery, and ileal vein. The Qpv was determined by an indicator dilution technique employing continuous constant infusion of 1% p-aminohippuric acid into the ileal vein. The VO2 by PVDO was estimated by multiplying Qpv by arterial-portal vein O2 difference measured with an arterial-venous O2 difference analyzer connected to the carotid artery and portal vein cannulas. Whole animal VO2 was measured with an open circuit indirect calorimeter. In seven pigs (3.5- to 4-month-old, 37.4 +/- 0.8 kg) trained to be fed once daily, feeding (1.2 kg of feed mixed with 1.2 liter of H2O) caused postprandial (6 hr) Qpv to increase more than 34 +/- 15% above the preprandial value of 34.5 +/- 4.2 ml.min-1.kg-1 body wt. The postprandial VO2 by PVDO was elevated more than 46 +/- 12% above the value of 1.52 +/- 0.20 ml.min-1.kg-1 body wt observed during the preprandial period. Whole animal VO2 increased 45 +/- 9 and 33 +/- 7% above the preprandial value of 6.23 +/- 0.57 ml.min-1.kg-1 body wt for the first 6 hr and the 7 to 12 hr after feeding, respectively. Although PVDO represent only 5% of body weight, they used 25% of whole body VO2. The study clearly illustrates the significance of PVDO on the whole animal oxidative demand in conscious growing swine.

Gross and microscopic anatomy of the kidney of the West Indian manatee, Trichechus manatus (Mammalia: Sirenia)

Examination of the gross and microscopic anatomy of the kidney of the West Indian manatee, Trichechus manatus, revealed that: (1) the medulla is about 6 times thicker than the cortex; (2) juxtamedullary glomeruli have a mean diameter 1.3 times greater than that of cortical glomeruli; (3) juxtamedullary glomeruli have 1.7 times as much volume as cortical glomeruli; (4) there are about twice as many cortical glomeruli as juxtamedullary glomeruli per square millimeter of cortical tissue, and (5) the vasa recta are closely juxtaposed to the thin loops of Henle in the outer medulla. Many of these results suggest an enhanced urine-concentrating ability in this species.

Prospective randomized trial of polytetrafluoroethylene and Dacron aortic prosthesis. I. Perioperative results

Over a two year period 80 patients were entered into a prospective randomized trial comparing polytetrafluoroethylene (PTFE) and Dacron infrarenal aortic reconstructions. Fifty-four patients were treated for aneurysm (30 single tubed grafts; 24 bifurcation grafts), and 26 patients were treated for occlusive disease (26 bifurcation grafts). The groups were matched for age, sex and preoperative risk factors. Five patients died after operation (6.3%) including two from hemorrhage, but there were no significant differences in mortality and morbidity between the PTFE and Dacron groups. The volume of blood lost at operation (1930 +/- 1340 ml, all patients); the volume of blood transfused (2.98 +/- 2.43 units); the volume of crystalloids infused (3050 +/- 1390 ml); the intraoperative heparin dosage (67.9 +/- 20.5 mg); the clamp time (71.6 +/- 34.5 min); and the total operating time (228.1 +/- 78.3 min) also showed no significant differences between PTFE and Dacron. The ankle systolic pressure index rose more for PTFE (0.96 +/- 0.24) than for Dacron (0.82 +/- 0.20; P less than 0.002) at the time of discharge. This partially reflects a difference in the index between the groups before operation (PTFE 0.79 +/- 0.30; Dacron 0.72 +/- 0.32), but it may also indicate that PTFE is less thrombogenic than Dacron.

Nd: YAG laser iridectomies: 100 consecutive cases

We reviewed the patient charts of our first 100 consecutive Nd:YAG laser iridectomies. Our success rate (99%) is the same as that reported by others. Iris bleeding was not problematic. We did find that relative pupillary block may still be present with a patent but very small Nd:YAG iridectomy; that transillumination is not an adequate criterion for assessing patency; and that a Nd:YAG laser iridectomy, probably in part because of its small size, frequently closes with chronic inflammation.

Effect of zinc source and picolinic acid on 65Zn uptake in an in vitro continuous-flow perfusion system for pig and poultry intestinal segments

Twenty weanling pigs and fourteen 9-wk-old broiler chickens were used in three continuous-flow in vitro perfusion experiments using noneverted intestinal sacs to 1) determine differences in 65Zn absorption due to location within the intestinal tract, 2) evaluate 65Zn uptake from ZnCl2 and Zn-methionine (ZnMet) with or without added picolinic acid (PA) in pig intestinal sacs and 3) evaluate 65Zn uptake from ZnCl2 and ZnMet in chicken intestinal sacs. No differences in 65Zn uptake due to gut segment position were observed in the pigs. A Zn source x PA interaction was observed for 65Zn uptake into the pig gut tissue and for 65Zn uptake to the serosal side of the gut sacs. Total 65Zn absorption in the pig gut sacs from the two Zn sources was not different, but the addition of a 5 M ratio of PA to Zn depressed 65Zn absorption. No differences were observed in total 65Zn absorption or 65Zn uptake in poultry gut sac tissue. There was, however, greater uptake of 65Zn from ZnCl2 to the serosal side of the sacs than from ZnMet. The data indicate that 65Zn from ZnCl2 and ZnMet is similar in total absorption and that the addition of PA depresses Zn uptake.

Influence of picolinic acid on the uptake of 65zinc-amino acid complexes by the everted rat gut

Three hundred fifty rats were used in three experiments to: 1) validate the everted gut procedure as an in vitro technique for estimating Zn absorption, 2) determine the effect of increasing ratios of picolinic acid (PA) to Zn on Zn absorption and 3) determine the effect of PA on absorption of Zn and amino acid complexes at pH 6, 7 and 8. In the first experiment the time delay between tissue collection with subsequent storage in ice-cold saline and start of tissue incubation was 0, 10, 20 or 30 min. A linear decrease was observed for 65Zn uptake with increasing delay time. Lysine absorption was not affected by delay time. In the second experiment, molar ratios of PA:Zn of 0, .5, 1.0, 1.5, 2.0 and 2.5 with Zn held constant were evaluated. A linear decrease in 65Zn absorption from 65ZnCl2 occurred as the molar ratio of PA to Zn increased. In the third experiment, 0 and 5 molar ratios of PA to a constant Zn level were evaluated using 65ZnCl2, 65Zn-14C-methionine (ZnMet) and 65Zn-3H-lysine (ZnLys) at pH 6, 7 and 8. The addition of PA decreased Zn absorption regardless of Zn source. The data suggest that the Zn sources used were of similar biological value. The data do not support the theory that PA facilitates Zn absorption.

Zinc-amino acid complexes for swine

Two experiments were conducted to determine the effect of sources of dietary zinc on gain, feed conversion and blood and bone traits of swine. In the first experiment 96 pigs were used in a 28-d study. The pigs were fed diets with no supplemental Zn or with either 9 or 12 ppm supplemental Zn from zinc sulfate (ZnSO4), zinc methionine (ZnMet) or zinc methionine with picolinic acid (ZnMet w/PA), each with or without 5% added corn oil. There were differences (P less than .05) in average daily gain (ADG) and average daily feed intake (ADFI) between the pigs fed the two organic Zn sources, with those fed ZnMet w/PA showing the better gains and feed conversion. However, neither organic Zn source resulted in pig performance that was different from either the diet with no supplemental Zn or the diets supplemented with Zn from ZnSO4. In the second experiment the same dietary Zn sources and treatments were fed as in Exp. 1 except that corn oil was deleted as a variable. No differences in ADG, ADFI, feed/gain (F/G) or in changes in serum Zn or Cu were observed among treatments during either the 21-d nursery or the 56-d growing periods. During the subsequent 56-d finishing period ADG and ADFI were greater (P less than .01) for pigs fed the Zn-supplemented diets than for those fed the diets without supplemental Zn. There were no differences among treatments in F/G during the finishing period. Zn content of bone ash was lower (P less than .01) in the non-Zn-supplemented pigs. These data suggest that the Zn sources used are of similar biological value and do not support the theory that picolinic acid aids Zn absorption.