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Biomedical subjects

K D Smith

Publications and source records attributed to K D Smith.

207 records · Page 12Linked to original sources
PubMedDate not supplied

Evaluation of sperm counts and total sperm counts in 2543 men requesting vasectomy.

Semen analyses were performed on semen specimens from 2543 men requesting vasectomy at Planned Parenthood of Houston and the results were compared to earlier reports of semen analyses in allegedly fertile men. The comparisons suggest that mean sperm counts and mean total sperm counts are significantly lower than those reported in 1951. Furthermore, a shifting pattern of frequency distribution of sperm counts and total sperm counts was noted. Greater percentages of men with sperm counts 20 million/ml and total sperm counts below 100 million/ejaculate were found in the present report and other recent reports than had been noted in 1951. These data suggest that standards of male infertility proposed in 1951 are no longer applicable.

Cell Count↗
PubMedDate not supplied

Adenosine antagonist properties of carbamazepine.

The binding of adenosine agonists and antagonists to the adenosine receptor is differentially affected by both temperature and guanine nucleotides. Agonist binding is facilitated at higher temperatures; the reverse is true for adenosine antagonists. In the present study, we demonstrate the feasibility of utilizing the temperature dependency of agonist/antagonist binding to the adenosine receptor in binding inhibition studies. We show that the anticonvulsant drug carbamazepine (CBZ) and several of its structural analogs behave in a manner identical to that of a series of adenosine antagonists; i.e., they are more potent inhibitors of [3H]cyclohexyladenosine (CHA) binding at 8 degrees C as compared to 37 degrees C and are equipotent as inhibitors of [3H]diethylphenylxanthine (DPX) binding at 0 and 30 degrees. We also show that the potency of CBZ and derivatives as inhibitors of [3H]CHA binding is markedly increased in the presence of 10 microM GppNHp, whereas their potency as inhibitors of [3H]DPX binding is unaffected by this guanine nucleotide. These data in conjunction with past studies support the hypothesis that CBZ and its derivatives act as adenosine antagonists at the level of binding interactions at the adenosine receptor.

Adenosine↗
PubMedDate not supplied

Utilization of commercial laboratory results in management of hyperandrogenism in women.

OBJECTIVE: To compare results from testosterone radioimmunoassay kits commonly used by commercial laboratories as well as their reference ranges and to analyze the scientific literature for ranges of serum testosterone levels in normal women and those with hyperandrogenism. METHODS: We reviewed quality assurance reports of various testosterone ligand challenges from four groups of laboratories and summarized testosterone data from 17 published reports about normal women and 14 studies of hyperandrogenic women. RESULTS: A significant variability was demonstrated between the radioimmunoassay kits at all concentrations (for example, a sample with a mean testosterone level of 96.1 ng/dL was reported by some laboratories as containing 71.8 ng/dL and by others as 123.4 ng/dL). All laboratories provide essentially the same "reference range" (approximately 10 to 90 ng/dL) but do not report how the range was established. The scientific literature clearly shows a significant separation in serum testosterone levels between normal (that is, not hyperandrogenic) and hyperandrogenic women. Most hyperandrogenic women had testosterone levels >50 ng/dL, whereas most normal control subjects had levels <40 ng/dL. Thus, most of these women with hyperandrogenism would have been considered to have normal testosterone levels if the reference ranges of commercial laboratories were used. CONCLUSION: These data illustrate the difficulty that physicians face when they are required to use different commercial laboratories to measure serum testosterone levels. We propose that (1) reference ranges be established on a clinically defined population for each hormone and method used, (2) laboratory reports include information about method and reference range population, and (3) physicians be allowed to choose which laboratories are used for their patients' hormone determinations, for consistency of results.

Journal Article↗
PubMedDate not supplied

Serum testosterone levels and reference ranges in reproductive-age women.

OBJECTIVE: To determine the levels of serum testosterone and dehydroepiandrosterone sulfate (DHEAS) in women with no clinical signs of hyperandrogenism and no history of glucocorticoid or oral contraceptive use and to compare these levels with the reference ranges provided by commercial laboratories. METHODS: We undertook a cross-sectional retrospective study of 271 reproductive-age women encountered at an endocrinology clinic for complaints of potential thyroid problems. Serum testosterone and DHEAS levels were determined, and statistical analyses were performed. RESULTS: The serum testosterone level in women with no acne, hirsutism, or menstrual dysfunction was 14.1 +/- 0.9 ng/dL (mean +/- standard error of the mean) (95% confidence interval [CI] = 12.4 to 15.8). This group was considered our study reference population. In women with menstrual dysfunction but no acne or hirsutism, the mean testosterone level was significantly higher (17.9 +/- 1.1 ng/dL; 95% CI = 15.7 to 20.0; P<0.002); with mild hirsutism, it further increased (38.4 +/- 5.1 ng/dL; 95% CI = 27.4 to 49.4; P<0.005); and with moderate to severe hirsutism, it was still higher (49.0 +/- 2.3 ng/dL; 95% CI = 44.4 to 53.6; P<0.003). Serum DHEAS levels showed similar patterns. The upper limit (mean + 2 standard deviations) of testosterone in our study reference population was 28 ng/dL, a level that provided a sensitivity of 84% for detecting hyperandrogenemia. The detection of hyperandrogenemia is essentially impossible when the upper limit of the reference range for testosterone from commercial laboratories (95 ng/dL) is used. CONCLUSION: The testosterone levels reported herein and in the literature for hyperandrogenic women both are within the reference (normal) ranges provided by commercial laboratories. These observations demonstrate why diagnosis of hyperandrogenemia in hyperandrogenic women is difficult when commercial laboratories are used and why this condition is not detected in most affected women. Commercial laboratories should reevaluate the methods used for establishing their reference ranges for serum testosterone.

Journal Article↗
PubMedDate not supplied

Development of an automatic control algorithm for the electrohydraulic total artificial heart without transducers.

To achieve a reliable and simple implantable total artificial heart, the number of implanted transducers providing the physiologic information required for automatic control should be minimized. To address this need, a new automatic control algorithm, based on a transducerless electrohydraulic total artificial heart (EHTAH) system, is proposed. The current EHTAH physiologic control algorithm relies on two implanted pressure transducers. Without these transducers, the information required for automatic control must be extracted from the running motor's parameters. These parameters correlated with the differential pressure across the axial flow pump used to actuate the EHTAH. Changes in this differential were chosen as a cue for cardiac output control. This algorithm can be viewed as depending upon systemic vascular resistance determined by subtracting mean right atrial pressure (RAP) from mean aortic pressure (AoP) and dividing the result by total cardiac output (CO). The difference between mean AoP and mean RAP was confirmed to correlate with the differential hydraulic pressure across the energy converter during the left systolic phase. As an interim configuration, a single differential pressure transducer measuring the differential hydraulic pressure across the energy converter was tested on a Donovan mock circulation system. The resultant CO response shows good sensitivity according to changes in both preload and afterload.

Algorithms↗
PubMedDate not supplied

Risk factors for pregnancy loss apparent at conception in infertile couples.

Charts of 206 consecutive pregnancies occurring in couples seen because of infertility were analyzed in an attempt to identify factors, apparent at the time of conception, which may impose risks on pregnancy outcome. These factors were compared in 34 spontaneous abortions and 172 full-term pregnancies. Although the mean age was similar in both groups, women 35 years or older had a significantly higher incidence of spontaneous abortion than younger women. Menstrual history, gravidity, and parity and incidence of previous induced abortions were not different in the spontaneous abortion and term groups. Data collected from basal body temperature charts suggested a slightly higher risk for spontaneous abortion in women with previous anovulatory cycles. The mean follicular phase in the conception cycle was 16 days in both groups. However, a twofold increase in abortion rate was noticed in conceptions with follicular phases shorter than 12 days or longer than 16 days, in comparison with those with follicular phases of 13-15 days' duration. The mean daily temperature increment in the early luteal phase was the same in both groups. No relation between sperm count or motility and spontaneous abortion was observed. Different treatment modalities during the conception cycle had no effect on abortion rate, except for a trend toward lower spontaneous abortion incidence in women who received only prednisone.

Abortion, Spontaneous↗
PubMedDate not supplied

Serum hormone changes in parturients given steroid preparations to suppress lactation.

Prior to the introduction of bromocriptine as the drug of choice for the suppression of puerperal lactation, long-acting sex steroid preparations, especially estrogen-androgen combinations, were utilized for many years to suppress postpartum lactation. In spite of the popularity of these steroids, little information is available concerning serum hormonal levels following their postpartum administration. In this study, 31 postpartum women were divided into three groups: group C, 12 women receiving no hormone therapy; group E + T, 10 women receiving an estrogen-testosterone preparation; group E, 9 women receiving an estrogen preparation. Immediately after delivery, serum estradiol, testosterone, and prolactin levels were elevated--and similar--in the three groups. Following treatment, serum estradiol levels were higher in groups E + T and E than in group C. In group E + T, serum testosterone levels increased to the high adult male range by 24 hours after injection and rose further to as high as 7,000 ng% (mean 2,000 ng%) by 72 hours. At 2 weeks, serum testosterone levels in this group of patients were still above the upper limit of the normal adult male range. After 6 weeks, the mean serum testosterone level was still five times the normal level for a nonpregnant female.

Adolescent↗
PubMedDate not supplied

Standards and criteria: group child care for sick children.

With the establishment of several statewide sick child care programs, a group of concerned health professionals recognized the need to develop guidelines and nursing care criteria for these centers. A task force was formed to design guidelines for the planning and development of facilities that provide care for children with recuperating illnesses.

Ambulatory Care Facilities↗