Outcomes of the first Family Practice Chief Resident Leadership Conference.

In June 1989 the first Family Practice Chief Resident Leadership Conference was presented to 27 Texas second-year residents who had been selected to serve as chief residents during their third year. The objectives of the conference were to assist these emerging leaders to develop better stress management and leadership skills and to strengthen their ties with the Texas Academy of Family Physicians. The conference featured two major workshops on stress management and leadership skills, and included plenary speeches and large and small group discussions. This article reports the outcomes of the conference as measured by the evaluation instrument completed by participants. Analysis of the results indicated that the conference had a positive effect on the residents.

Sexual identity and practices relating to the spread of sexually transmitted diseases.

All sexually transmitted diseases are behaviorally correlated. A thorough understanding of the behaviors involved in the spread of sexually transmitted disease will increase the physician's ability to suspect, properly identify, and treat the disease. An appreciation of the common sexual behavior in contemporary American society will allow the physician to more effectively address patients' concerns about their sexuality and sexual behavior and identify areas for which further professional counseling is appropriate. Physicians are the most trusted source of health information, often counsel their patients on intimate subjects, and therefore are in a unique position to promote individual behavioral and perceptual changes for limiting the spread of sexually transmitted disease. Physicians must, therefore, be aggressive in taking sexual histories, especially for young, sexually active patients, whether heterosexual, homosexual, or bisexual. Clinicians must deliberately cultivate a comfortable, sympathetic attitude and provide an environment in which a complete and honest sexual practices history will freely flow. Once the patients at risk for STDs are identified, the physician should attempt to counsel them to reduce their risk through safer sexual practices. If little office time is available for these sensitive educational issues, then the physician should identify individuals within the office or appropriate programs in the community for referral. Representative data on the sexual behavior of all Americans will be relevant not only to the AIDS crisis but also to other national sex-related problems such as the growing incidence of chlamydia, other sexually transmitted diseases, and the costly multigenerational impact of epidemic teenage pregnancy. Comprehensive, well-designed studies of contemporary sexual behavior are needed now.

Nicardipine and propranolol in the treatment of hypertension: similar antihypertensive but dissimilar hemodynamic actions.

Although the precise cause of essential hypertension is not known, empiric treatment is indicated to reduce cardiovascular risks. Several pharmacologic classes of a antihypertensive drugs are available to reduce blood pressure, but they do so by different hemodynamic mechanisms. The physiologic therapeutic goal in patients with hypertension is to normalize the systemic vascular resistance without inducing major alterations in the cardiac output. In this study we compared the antihypertensive and hemodynamic actions of nicardipine, a calcium antagonist, with propranolol, a beta-blocking drug. Both drugs were effective in the treatment of hypertension. However, while propranolol therapy decreased the resting and exercise left ventricular ejection fraction and cardiac output, cardiac function was well preserved during nicardipine therapy. It is concluded that both nicardipine and propranolol exert similar antihypertensive actions but that they cause dissimilar hemodynamic consequences in patients with uncomplicated hypertension.

Calcium antagonists in the treatment of hypertension. An overview.

The availability of calcium antagonists has provided yet another therapeutic option in the management of hypertension. Calcium antagonists lower the blood pressure in hypertensive individuals while preserving the blood flow at the microcirculatory level. While all the available calcium antagonists are effective in the treatment of hypertension, they differ in their hemodynamic and pharmacologic actions. Nifedipine appears to be suitable for immediate treatment of severe hypertension and for chronic treatment of uncomplicated or refractory hypertension. In some but not all patients, co-administration of a beta-blocker is necessary to blunt reflex tachycardia. This problem is less likely with the tablet/long-acting formulation of nifedipine. Verapamil and diltiazem are useful as initial therapy for chronic mild-to-moderate hypertension. They are as effective as other first-line drugs in the treatment of uncomplicated hypertension. The heart rate with verapamil or diltiazem does not change or is slightly reduced, thus contrasting with nifedipine. Experience to date suggests that calcium antagonists do not cause adverse biochemical effects and in this respect are superior to diuretics and certain beta-blockers. Currently, verapamil is available as a sustained release preparation. In the near future, nifedipine or diltiazem may also be available in the long acting formulation to permit simplicity and to enhance patient compliance in the treatment of hypertension.

Effects of D-amino acids on growth rate and kidney D-amino acid oxidase in chicks.

Studies were conducted on the effects of feeding D-amino acids on growth rate and D-amino acid oxidase (DAAO) in chick kidney. The crystalline amino acid (AA) diet provided seven amino acids either in the L-form or the DL-form at two concentrations (DL- or .5 DL-AA diets) with all diets containing equal amounts of L-amino acids. Weight gains of chicks fed the DL-AA diet were consistently lower than those fed the L- or .5 DL-AA diet. Kidney DAAO activity was significantly higher in chicks fed either the DL-AA or .5 DL-AA diet as compared with the L-AA diet. Kidney DAAO activity was essentially the same in chicks fed the DL- and .5 DL-AA diets. Increasing the nonspecific nitrogen in the diet had no effect in alleviating growth depression of the DL-AA.

Effects of a nonspecific nitrogen deficiency on growth rate and leg problems in chicks.

Five experiments were conducted using crystalline amino acid and semipurified diets containing adequate levels of all indispensable amino acids, vitamins, and minerals to study the effects of dispensable amino acids on growth and the incidence of leg abnormalities of male chicks. Purified diets containing 5% L-glutamic acid as the sole source of nonspecific nitrogen resulted in poor growth and feed efficiency, high mortality, and a high incidence of leg abnormalities with many severe cases of this condition. Increasing the dietary level of L-glutamic acid to 10% of the purified diet or supplementing the 5% L-glutamic acid diet with 2.40% glycine or 1.68% L-serine improved weight gain but did not eliminate the leg conditions. Higher L-serine (3.36%) resulted in a growth depression, indicating that this level was toxic to the birds. It was necessary to increase the dietary L-glutamic acid to 12.5% to reduce the incidence of leg problems to a minimum. Plasma dispensable amino acid levels (aspartic acid, glutamic acid, and alanine) paralleled the levels of L-glutamic acid in the diets fed to the chicks. Plasma serine and glycine levels were increased by adding either serine or glycine, but the magnitude of the increase of either amino acid was greatest with the addition of that amino acid to the diet. Plasma proline concentrations increased when chick diets were supplemented with high levels of glycine (2.4%), serine (3.36%), or glutamic acid (9.7%) in relation to those supplemented with only 5% L-glutamic acid. Feeding an intact protein (isolated soybean protein) diet did not alleviate leg disorders, although it did improve weight gain.

The effects of sorghum tannin and protein level on the performance of laying hens maintained in two temperature environments.

A study was conducted to investigate the effect of sorghum grain tannins on the performance of laying hens. A total of 144 White Leghorn hens were arrayed according to egg production during a 10-day preexperimental period into eight groups consisting of four nutritional treatments in each of two constant temperature environments (22 and 28 C). The nutritional treatments consisted of low (RS610) and high (Savanna) tannin sorghum grains compared isonitrogenously within a protein level at two protein levels (11.5 and 14.5%) in sorghum-soybean meal diets. These diets were fed for an experimental period of 6 weeks. Egg production and feed efficiency were reduced and weight loss was increased by 11.5% protein as compared with 14.5% protein. Tannin significantly reduced egg production and feed efficiency at both protein levels while egg specific gravity and shell thickness were adversely affected only at the lower level of protein. Egg weight and weight loss of hens were not affected by tannin. Except for weight loss, all parameters were slightly reduced by the higher temperature. At the end of the experiment, all hens were placed on a commercial laying ration for a 31-day period. Recovery from the treatment effects was evidenced by the similar egg production, body weight, egg weight, and shell characteristics among the previous treatments at the end of this period.

Influence of phenylalanine and lysine deficiencies on thyroid morphology in the chick.

A study was conducted to investigate the effects of dietary phenylalanine and lysine deficiencies on thyroid morphology in chicks fed crystalline amino acid diets. Both mean follicle diameter and epithelial cell height were significantly reduced in birds fed either of the deficient diets as compared with controls. These results agree with previous studies on serum T4 and T3 concentrations where the effects of an amino acid deficiency were general and not limited to precursors of thyroxine.

Methionine-cystine interrelationships in chicks and rats fed diets containing suboptimal levels of methionine.

Studies were continued with both chicks and rats on the previously reported (featherston and Rogler, 1978) growth depression observed when a crystalline amino acid diet adequate in all nonsulfur-containing amino acids and containing .2% DL-methionine and .2% L-cystine was supplemented with an additional .2% L-cystine. In the present investigation, an average growth depression of 37% was observed in chicks fed a diet containing .4% L-cystine and .2% DL-methionine as compared with chicks fed a diet containing .2% L-cystine and the same level of methionine. A comparable depression was noted when cystine was replaced by L-cysteine. In contrast, an additional .2% of another amino acid (L-tryptophan) did not depress growth. When the high and low cystine diets were meal-fed, results obtained were similar to those observed with ad libitum feeding, but the magnitude of the difference was reduced. Foot-pad lesions, similar to those described in turkey poults fed methionine-deficient diets, were observed in two experiments. Factorial analysis of plasma amino acids indicated that the total of all amino acids analyzed was significantly (P < .05) higher in chicks fed the lower cystine or cysteine diets. Plasma methionine was slightly lower (P < .10) but plasma cystine was significantly (P < .05) higher in chicks fed the cystine or cysteine supplemented diets. A study with .2 and .4% L-cystine and 200, 600, and 2000 mg/kg of choline (factorial design) demonstrated a significant (P < .05) depression in weight gain due to the added L-cystine, no significant (P < .05) differences due to choline, and the absence of a cystine-choline interaction. No detrimental effects were observed when weanling rats were fed a crystalline amino acid diet containing .1% DL-methionine and .2% L-cystine supplemented with additional L-cystine.

Influence of dietary cystine on intestinal absorption and tissue distribution of methionine in the chick.

Studies were conducted on intestinal absorption and tissue distribution of methionine by chicks fed a crystalline amino acid diet containing .2% DL-methionine and .2 or .4% L-cystine or L-cysteine. Chicks fed the higher level of cystine or cysteine had previously been shown to exhibit depressed growth as opposed to chicks fed the lower level of these amino acids. In two experiments, 35S radioactivity of whole plasma and the protein and supernatant fractions were compared among chicks fed the different treatments at 30 or 60 min after oral intubation of L-[35S]-methionine into the crops. When the data were analyzed factorially, a significant level effect was noted for whole plasma and the protein and supernatant fractions, all of which were higher for chicks fed .2% L-cystine than those fed .4% L-cystine. Results with chicks fed the two levels of L-cysteine generally agreed with those of chicks fed L-cystine, although the differences were not as great. The labeled methionine was also added to diets containing .2 or .4% L-cystine of meal-fed chicks. Higher levels of radioactivity were observed in the liver but not in muscle or plasma of chicks fed the lower level of cystine at 7 hr after oral consumption of the isotope. No significant differences in liver, muscle, or plasma radioactivity were noted in a fourth experiment between chicks fed .2 or .4% L-cystine at 24 hr after intraperitoneal injection of L-[35S]-methionine. In vitro studies showed no differences in methionine accumulation by isolated intestinal segments incubated with three levels of cystine.

Effects of dietary phenylalanine and tyrosine on circulating thyroid hormone levels and growth in the chick.

Studies were conducted to investigate the effects of a phenylalanine-tyrosine deficiency on serum thyroid hormone concentrations and growth in chicks from 0 to 14 days of age. Birds fed diets severely deficient in aromatic amino acids (AAA), lysine or valine were found in most trials to have reduced serum concentrations of either 3,5,3'-triiodothyronine (T3) or 3,5,3',5'-tetraiodothyronine (T4). Approximately one-half of the samples assayed did not show detectable levels of 3,3',5'-triiodothyronine (reverse T3). The reduction in serum thyroid hormone levels was not observed until chick growth was markedly affected and was not specific for AAA deficiency. Phenylalanine alone could not efficiently supply tyrosine when dietary AAA were suboptimal as evidenced by significantly greater weight gains in chicks fed 50:50 or 55:45 (mole:mole) mixtures of phenylalanine and tyrosine as compared with birds fed the same total amount (moles) of AAA supplied solely by phenylalanine. However, at or above requirement levels, phenylalanine could completely meet the chick's demand for tyrosine. Serum tyrosine concentrations generally reflected the dietary levels of AAA.

Methionine-cystine interrelations in chicks fed diets containing suboptimal levels of methionine.

Studies were conducted with chicks on the interrelationship between cystine and methionine in either crystalline amino acid or wheat-peanut meal diets containing suboptimal levels of these two amino acids. The crystalline amino acid basal diet contained 0.2% DL-menthionine and 0.2% L-cystine whereas the wheat-peanut meal diet contained 0.2% methionine and 0.26% cystine. Marked improvements in weight gain and feed efficiency were observed when these diets were supplemented with 0.2 to 0.6% DL-methionine. When similar levels of L-cystine were added to the basal diets containing 0.2% methionine, chick growth was depressed. When the diets contained 0.4% methionine, the growth depressing effect of cystine was not observed. These results point to the existence of an antagonism of cystine on methionine utilization when the dietary level of methionine is suboptimal.

Investigations of leg abnormalities in chicks consuming high tannin sorghum grain diets.

Studies were conducted into the etiology of leg abnormalities noted in chicks fed high tannin sorghum grain diets. These anomalies were characterized by a bowing of the legs with a swelling of the hock joints. The incidence of these leg problems was found to be markedly higher when the amino acids in the diet provided by soybean meal were replaced by crystalline amino acids. Supplemental vitamins and minerals had no alleviating effect on the leg problem. Bone mineralization was apparently not influenced by tannins as demonstrated by similar bone ash values for chicks fed high or low tannin sorghums. A possible alteration caused by tannin in the organic matrix of bone is discussed. High tannin sorghum depressed chick growth and feed conversion when compared with low tannin sorghum in both sorghum-soybean meal and sorghum-amino acid rations. This growth depression was overcome by supplementing the high tannin sorghum-soybean meal diet with .15% DL-methionine, but no growth response was observed from a similar supplementation of a high tannin sorghum-amino acid diet.

Glycine-serine interrelations in the chick.

Glycine and serine are involved in numerous important functions in the body in addition to protein synthesis. Glycine is synthesized by higher animals; however, the rate is not adequate to support maximal growth of the chick. Studies indicate that chicks fed a glycine-serine free crystalline amino acid diet grow at approximately 80% the rate of chicks fed the same diet supplemented with glycine. An equimolar quantity of L-serine has been shown to support equal chick performance as glycine, thus indicating that serine conversion is adequate to meet the dietary need for glycine. The serine-glycine interconversion is catalyzed by the folic acid containing enzyme sering hydroxymethyltransferase, and a deficiency of this vitamin decreases the effectiveness of serine in meeting the chick's dietary need for glycine. Studies with chicks fed normal and high levels of a crystalline amino acid mixture devoid of glycine and serine indicate that the chick has the metabolic potential to synthesize more of these two amino acids than should be required for normal growth. The observed dietary response to glycine or serine or both indicates, however, that this synthetic potential is not being utilized.

Uric acid excretion by the chick as an indicator of dietary protein quality.

The objective of this investigation was to determine whether uric acid excretion could serve as an indicator of dietary protein quality. In the first study, 15% protein diets were formulated using either whole egg protein, soybean meal, safflower meal or casein, or the latter 3 proteins supplemented with their most limiting amino acid (methionine, lysine and arginine, respectively). Chicks fed diets supplemented with the limiting amino acid grew more rapidly and efficiently and excreted less uric acid. Good agreement was noted between uric acid excretion and protein efficiency ratio (PER) as indicators of protein quality. Two studies were conducted with chicks fed diets containing raw soybean flakes or flakes autoclaved for varying periods of time and fed with or without methionine and lysine supplementation. Similar chick performance, uric acid excretion and PER were noted with chicks fed the soybean flakes which had been autoclaved for 20, 40 or 120 min. Poorer chick performance and PER were noted with chicks fed soybean flakes or flakes autoclaved for 10 min. When the diets were supplemented with methionine and lysine, the negative effects of inadequate heating were partially alleviated. The results indicated that adequate heating and amino acid supplementation of soybean flakes were both essential for maximal chick performance, that the two factors influence the utlization of the protein in different ways and that the two effects were additive.

Relative utilization of serine and glycine by chicks.

Studies were conducted on the relative utilizaiton of glycine and serine by chicks fed basal crystalline amino acid diets devoid of these amino acids. The crystalline amino acid mixture was fed at one and three times the requirement levels, thereby stimulating uric acid synthesis at differing rates. In addition, 5 per cent L-glutamine replaced L-glutamic acid on an isonitrogenous basis in three diets containing normal levels of amino acids in the second study. Chicks fed diets devoid of glycine and serine grew less rapidly and less efficiently than chicks fed diets containing either serine or glycine plus serine. These decreases were roughly the same whether the diet contained normal or high levels of amino acids. Serine was as efficient as glycine in supporting chick growth and feed efficiency regardless of whether diets containing normal or high levels of amino acids were fed. Chicks fed diets containing high levels of amino acids grew approximately 81 per cent as rapidly, but 24 per cent more efficiently, than chicks fed normal levels of amino acids, and excreted approximately twice the amount of uric acid per gram of nitrogen consumed. In spite of increased uric acid excretion by chicks fed the high amino acid diets, the dietary void in glycine and serine was no more detrimental to chick growth or feed efficiency than that noted when normal levels of amino acids were fed. Feeding 5 per cent L-glutamine rather than L-glutamic acid in the diet containing normal levels of amino acids had little effect on weight gain, feed efficiency or uric acid excretion. The absence of cystine from the amino acid mixture used in the third study did not have a marked influence on the relative utilization of glycine and serine by the chick.