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Biomedical subjects

J K Williams

Publications and source records attributed to J K Williams.

At least 127 records · Page 7Linked to original sources
PubMed1992

School-aged children with Turner's syndrome.

Turner's syndrome (TS) is an abnormality of the X chromosome associated with cognitive and psychosocial adjustment problems as well as congenital anomalies. Children with TS are at risk for problems in academic achievement and psychosocial development. Recognition of these risks allows nurses to provide nursing interventions including anticipatory guidance, facilitation of parental interactions with the school, and interventions for management of problems in psychosocial development.

Adolescent↗
PubMed1991

Fluoro-Gold's toxicity makes it inferior to True Blue for long-term studies of dorsal root ganglion neurons and motoneurons.

We studied the long-term effects of two retrogradely transported fluorescent dyes on survival of dorsal root ganglion neurons (DRGNs) and motoneurons (MNs). In adult female rats, we labeled DRGNs and MNs by soaking the cut sciatic nerve in Fluoro-Gold or True Blue. With True Blue, we found no difference in the number of labeled MNs or DRGNs in rats surviving 4 days or 20 weeks after nerve soak. With Fluoro-Gold, labeled DRGNs and MNs were decreased at 20 weeks compared with 4 days. Since there was no offsetting increase in unlabeled DRGNs at 20 weeks, Fluoro-Gold caused cell death.

Animals↗
PubMed1991

Effects of oestrogens and progestogens on coronary atherosclerosis and osteoporosis of monkeys.

We have used the cynomolgus macaque as a model for the study of the effects of endogenous and exogenous sex steroid hormones on atherosclerosis and osteoporosis. As in human beings, premenopausal female cynomolgus macaques develop much less extensive coronary artery atherosclerosis than their male counterparts. Furthermore, surgical menopause results in a more atherogenic plasma lipoprotein pattern and an approximate doubling of atherosclerosis extent. Frequent pregnancy, a hyperoestrogenic state, results in an approximate 50% reduction in atherosclerosis extent. Physiological replacement with 17 beta-oestradiol alone or in combination with progesterone prevents the increase in coronary artery atherosclerosis extent associated with ovariectomy. This effect is independent of plasma lipoprotein concentrations and appears to be accounted for, at least in part, by an inhibitory effect of oestrogen replacement therapy on the uptake and degradation of LDL by the artery wall. Also, as in human beings, treatment with certain types of combination oral contraceptives results in marked decreases in plasma HDL-C concentration. Nonetheless, coronary artery atherosclerosis extent is reduced in monkeys by oral contraceptive treatment, and this effect is most pronounced among animals at highest risk due to theoretically adverse plasma lipoprotein profiles. It appears that, as with oestrogen replacement therapy, this effect can be accounted for, at least in part, by an inhibition of the uptake and degradation of low density lipoprotein by the artery wall. The monkey also appears to be a good model for studies of postmenopausal bone loss. As in women, surgical menopause results in significant diminution of bone mineral density and bone mineral content. Also, serum biomarkers of bone turnover (total alkaline phosphatase, acid phosphatase, tartrate-resistant acid phosphatase and osteocalcin) are increased in surgically postmenopausal monkeys, indicating increased bone turnover resulting from the surgical menopause. These increases in bone loss and indices of bone turnover were prevented by physiological oestrogen replacement therapy. Cynomolgus monkeys seem to be exceptionally useful models for studies of the effects of sex steroid hormones on atherosclerosis and osteoporosis, two major public health problems in postmenopausal women.

Animals↗
PubMed1991

Loss of flow-mediated endothelium-dependent dilation occurs early in the development of atherosclerosis.

BACKGROUND: Healthy arteries exhibit endothelium-dependent dilation in response to both local acetylcholine and increased blood flow. In humans, clinically overt coronary artery disease is characterized by loss of dilation to both acetylcholine and blood flow. The temporal relation, however, between functional abnormalities of the endothelium and the development of atherosclerosis has not been established. METHODS AND RESULTS: We examined endothelial vasodilator function in vivo at an early stage of the development of atherosclerosis. Two groups of seven Macaca fascicularis monkeys were studied; one group was fed a high cholesterol diet (0.73-1.0 mg cholesterol per calorie) for 11 months. Cholesterol feeding was associated with increased plasma cholesterol levels and with intimal thickening of the iliac arteries but with no reduction in luminal diameter. Endothelium-dependent vasomotor responses of the iliac arteries were then examined in vivo by quantitative contrast angiography. Acetylcholine produced significant dilation in the controls but paradoxical constriction in the group with early atherosclerosis (+9.0 +/- 3.2% versus -5.3 +/- 5.4%, p less than 0.05). In response to a twofold increase in blood flow achieved by administering adenosine distal to the arterial segment under examination, the controls again dilated, whereas the atherosclerotic group failed to dilate (+ 11.6 +/- 2.1% versus + 0.5 +/- 2.4%, p less than 0.05). Both groups, however, were able to dilate, and dilated equally, to the nonendothelium-dependent agent nitroglycerin (+ 13.7 +/- 4.8% versus + 19.1 +/- 4.3%, NS). CONCLUSIONS: Endothelium-dependent vasodilation in response to both acetylcholine and increased blood flow may be lost early in the course of developing atherosclerosis before the appearance of stenosing and occlusive disease.

Acetylcholine↗
PubMed1991

Psychosocial factors impair vascular responses of coronary arteries.

BACKGROUND: Four sets of monkeys were used to examine the effect of chronic psychosocial disruption and diet on dilator responses of coronary arteries. METHODS AND RESULTS: One set consisted of monkeys consuming monkey chow and living in a stable social setting (nonatherosclerotic controls, n = 6). Three sets consumed an atherogenic diet for 14 months followed by one of three treatments for the next 16 months: 1) a high-cholesterol diet and housed in unstable social groups (n = 9); 2) a low-cholesterol diet and housed in unstable (n = 8); or 3) stable groups (n = 10). Quantitative coronary angiography revealed that intracoronary infusion of acetylcholine resulted in a change of diameter (versus infusion of 5% dextrose in water) of +4 +/- 1% in control monkeys and -11 +/- 4% in unstable monkeys consuming a high-cholesterol diet (p less than 0.05). In monkeys consuming the cholesterol-lowering diet, the change in artery diameter was +2 +/- 4% in stable and -10 +/- 4% in unstable social conditions (p less than 0.05) despite a similar plaque size (0.4 +/- 0.2 and 0.5 +/- 0.1 mm2) and total plasma cholesterol concentrations (179 +/- 9 and 172 +/- 6 mg/dl), respectively. The arterial response to nitroglycerin was similar among all groups of monkeys. CONCLUSIONS: We conclude that chronic social disruption is associated with relative arterial constriction in response to acetylcholine in atherosclerotic monkeys consuming a cholesterol-lowering diet.

Animals↗
PubMed1991

Coronary heart disease in rhesus monkeys with diet-induced coronary artery atherosclerosis.

Diet-induced coronary artery atherosclerosis develops in rhesus monkeys (Macaca mulatta). The goal of this study was to establish the rhesus monkey as an animal model of coronary heart disease (CHD). From a colony of 160 rhesus monkeys fed an atherogenic diet, we identified 14 monkeys with electrocardiographic and echocardiographic evidence of CHD. When compared with 14 rhesus monkeys matched for age, gender, and dietary history with normal electrocardiograms and echocardiograms, monkeys with CHD had higher arterial blood pressures (mean +/- SEM, 92 +/- 4 mm Hg vs 75 +/- 5 mm Hg, respectively), lower high-density lipoprotein cholesterol concentrations (mean +/- SEM, 1.70 +/- 0.25 mmol/L vs 2.32 +/- 0.28 mmol/L [66 +/- 10 mg/dL vs 90 +/- 11 mg/dl]), and lower A-l apolipoprotein concentrations (mean +/- SEM, 200 +/- 17 mg/dL vs 252 +/- 15 mg/dL). Monkeys with CHD tended to have higher total plasma cholesterol concentrations (mean +/- SEM, 11.6 +/- 1.55 mmol/L vs 9.36 +/- 0.93 mmol/L [450 +/- 60 mg/dL vs 362 +/- 36 mg/dL]) and higher low-density lipoprotein cholesterol concentrations (mean +/- SEM, 8.71 +/- 1.75 mmol/L vs 6.12 +/- 0.90 mmol/L [337 +/- 68 mg/dL vs 237 +/- 35 mg/dl]) than monkeys with normal electrocardiograms and echocardiograms. We conclude that rhesus monkeys, like human beings, develop CHD as a complication of coronary artery atherosclerosis. Furthermore, risk factors for CHD in rhesus monkeys and human beings are similar.

Animals↗
PubMed1991

Synthesis of IL-1 alpha and IL-1 beta by arterial cells in atherosclerosis.

Interleukin-1 (IL-1) has been implicated as a regulatory protein in the development and clinical sequelae of atherosclerosis. To determine which cells in the atherosclerotic plaque synthesize IL-1 in situ, the authors evaluated histologic sections of iliac arteries from cynomolgus monkeys using probes for IL-1 alpha and beta. A polyclonal antibody to IL-1 alpha and beta was used to determine if proteins were concomitantly produced. The predominant cells expressing IL-1 alpha and beta mRNA were foam cells in the intima. Adherent leukocytes and vascular smooth muscle cells (VSMCs) expressed mRNA for IL-1 alpha. Microvascular endothelium expressed mRNA for both IL-1 alpha and beta. IL-1 proteins were located frequently in cells expressing IL-1 mRNA. These results indicate that endothelium and VSMCs, in conjunction with macrophages, serve as localized sources of IL-1 protein synthesis. These findings suggest that vascular cells may contribute directly to the pathogenesis of atherosclerotic vascular disease by actively secreting potent biologic mediators that modify vascular and immune cell function.

Animals↗
PubMed1991

Oral contraceptives and reproductive system cancer. Benefits and risks.

Large epidemiologic studies conducted to date in the United States and abroad have not demonstrated any statistically significant increase in the overall incidence of breast cancer among women who used oral contraceptives (OCs). The cumulative risk of breast cancer among women less than 60 years of age is clearly not related to OC use, although the incidence of breast cancer in certain subgroups of premenopausal women who used OCs may be increased and warrants monitoring. Evidence of a latency period in the development of breast cancer among OC users is not convincing. Studies to date have indicated that the risk of invasive cervical cancer appears to be unaffected by OC use. The data on cervical intraepithelial neoplasia are inconclusive and fraught with confounding variables. There is unequivocal evidence that OC use reduces the incidence of other reproductive system cancers, notably ovarian and endometrial.

Breast Neoplasms↗
PubMed1990

Use of the labor-delivery-recovery room in an urban tertiary care hospital.

Single-room maternity care is an attractive delivery system to obstetricians and consumers. We reviewed the first 15 months' experience in a committed labor-delivery-recovery room unit where all patients were admitted for single-room care regardless of risk. The rate of transfer to a traditional delivery room for vaginal delivery was 3.8%.

Delivery Rooms↗
PubMed1990

Retrograde transport of fluoro-gold in corticospinal and rubrospinal neurons 10 and 20 weeks after T-9 spinal cord transection.

Retrograde labeling with horseradish peroxidase is greatly diminished in corticospinal and rubrospinal neurons axotomized by complete T-9 spinal cord transection. We found, 10 or 20 weeks after a complete T-9 cord transection, that the number of corticospinal and rubrospinal neurons retrogradely labeled after Fluoro-Gold insertion into a new transection at T-1 did not differ from that of controls. While transection alters uptake, transport, and/or intracellular metabolism of some transportable substances, it does not affect the ability of the neurons to be retrogradely labeled with Fluoro-Gold.

Animals↗
PubMed1990

Thrombin activity induced by balloon angioplasty of the coronary artery in Macaca fascicularis (cynomolgus monkey).

In this paper we address the question of whether balloon angioplasty induces thrombin action. In the studies reported here we measured fibrinopeptide A levels in a group of atherosclerotic monkeys undergoing coronary angioplasty. A blood collection catheter was introduced into the inferior vena cava through a femoral vein, and the angioplasty catheter introduced via the femoral artery. Heparin was administered immediately after insertion of the arterial catheter. Serial blood samples were collected for 20 min before angioplasty and for 10 min after angioplasty. Baseline levels of FpA were high, presumably in response to the trauma of introducing the catheters. After heparin administration the FpA concentration declined with a half-time of 1.1 min. In response to balloon inflation there was a clear increase in the concentration of FpA, despite the presence of a therapeutic concentration of heparin. The magnitude of the FpA rise was markedly different between animals, but was evident in the aggregate data after subtraction of background levels of FpA. By integration of the plasma FpA concentration curve, the amount of fibrinogen converted to fibrin in response to angioplasty was calculated to be approximately 0.4 mg/animal. We conclude that angioplasty induces significant activation of the coagulation system.

Angioplasty, Balloon, Coronary↗
PubMed1990

Major trauma in pregnant women: maternal/fetal outcome.

One regional trauma center's experience with a large number of seriously injured pregnant women was reviewed to identify factors affecting maternal and fetal outcome after injury. Of 318 pregnant women who suffered trauma from January 1984 through December 1988, 25 (8%) were severely injured and would have required hospital admission even in the absence of pregnancy. Physical examination, except for the inappropriate absence of fetal heart tones, was a poor predictor of fetal status. Sonography proved to be the most accurate modality for acutely assessing fetal status. There was one (4%) maternal death, consistent with predicted mortality (TRISS methodology). Four pregnancies were lost and one neonate died because of injuries sustained, not because of surgery or anesthesia. There was significant difference between the ISS (average, 9) and CTS (average, 16) of women with surviving pregnancies or successful deliveries and the ISS (average, 30) and CTS (average, 12) of women who lost pregnancies or witnessed neonatal death. Fetal outcome relates to direct fetal injury and to the acute hemodynamic insult associated with maternal trauma. Maternal evaluation and treatment should occur in a stepwise and organized fashion following the general principles of trauma care (ATLS guidelines) in conjunction with perinatal specialists. Uterine ultrasonography should be an integral component of the initial evaluation. With expedient resuscitation, evaluation, and intervention, maternal and fetal survival can be expected.

Adolescent↗
PubMed1990

Estrogen modulates responses of atherosclerotic coronary arteries.

Although evidence indicates that estrogen replacement therapy reduces risk of coronary heart disease, the mechanism remains unknown. Among the possibilities are that estrogen replacement therapy may 1) inhibit growth of atherosclerotic plaque and 2) decrease the prevalence of transient myocardial ischemia and myocardial infarction by modulating vasomotion in atherosclerotic coronary arteries. Using quantitative coronary angiography, we determined vasomotor responses of atherosclerotic coronary arteries in ovariectomized cynomolgus monkeys; six were given physiological estrogen "replacement" by subcutaneous implants, and six were not. Intracoronary infusion of the endothelium-dependent dilator acetylcholine (1 X 10(-6) M) caused paradoxical constriction of coronary arteries (from 1.2 +/- 0.2 to 0.6 +/- 0.1 mm, p less than 0.05) in the estrogen-deficient monkeys. However, acetylcholine tended to minimally dilate the left circumflex coronary artery in estrogen-treated monkeys (from 1.2 +/- 0.2 to 1.5 +/- 0.2 mm, p greater than 0.2). Although estrogen replacement therapy reduced plaque extent in coronary arteries, altered vasomotion was not related to plaque extent. We conclude that estrogen modulates vasomotion of atherosclerotic coronary arteries of monkeys and speculate that estrogen-modulated constrictor responses of atherosclerotic coronary arteries may reduce the incidence of coronary heart disease in postmenopausal women.

Acetylcholine↗
PubMed1990

Evaluation of blunt abdominal trauma in the third trimester of pregnancy: maternal and fetal considerations.

With the active life-style of today's pregnant women, the effects of trauma have become an important obstetric concern. A protocol was developed to monitor pregnancies complicated by major blunt abdominal trauma in the third trimester, looking specifically for delayed placental and/or fetal problems. Of the 84 pregnancies studied, the most serious complication was placental abruption. Although abruption occurred in only two cases, one case was associated with a ruptured uterus and fetal death. There were no cases of delayed abruption or delayed fetal compromise. The most common complication was preterm labor, occurring in 28% of cases when the traumatic insult happened before 37 weeks' gestation. Of these 17 patients, 15 were successfully treated with tocolysis. There were no cases of direct fetal injury or Rh-isoimmunization. A revised protocol is recommended for limited outpatient observation with nonstress testing and screening ultrasonography to rule out preterm labor and placental abruption and to document fetal well-being.

Abdominal Injuries↗
PubMed1989

Vasa vasorum in the carotid sinus of atherosclerotic monkeys: implications for baroreceptor function.

The carotid sinus is unusually susceptible to development of severe atherosclerotic lesions. The purposes of this study were to examine effects of atherosclerosis on blood flow through vasa vasorum in the carotid sinus and to examine responses to humoral stimuli. Blood flow to vasa in the carotid sinus was measured with microspheres in 8 normal and 9 atherosclerotic cynomolgus monkeys. Blood flow to vasa in intima-media (in ml/min per 100 g) was 0.5 +/- 0.3 (mean +/- SE) in normal and 21 +/- 5 in atherosclerotic monkeys (P less than 0.05). Flow to adventitial vasa was 37 +/- 5 in normal monkeys and 50 +/- 7 in atherosclerotic monkeys (P greater than 0.05). Infusion of phenylephrine did not affect blood flow in normal or atherosclerotic monkeys. Infusion of serotonin did not affect blood flow to vasa in normal monkeys, but decreased flow to vasa in both intima-media and adventitia of atherosclerotic monkeys. In normal media, histological examination demonstrated the presence of a few vasa vasorum, which penetrated from adventitia. In atherosclerotic monkeys, medial vasa were much more frequent. Thus, (1) atherosclerosis produces marked increases in blood flow through vasa in intima-media of the carotid sinus, probably as a consequence of proliferation of vasa, and (2) in atherosclerotic monkeys, vasa constrict in response to serotonin. Based on these findings, we speculate that when serotonin is released as platelets aggregate at plaques in the carotid artery, serotonin may be delivered through vasa to nerves in the carotid sinus and thereby affect baroreceptor function.

Animals↗
PubMed1989

Hypothesis: vasoconstriction contributes to amaurosis fugax.

Platelets play a critical role in the pathophysiology of amaurosis fugax. Emboli to retinal vessels apparently produce amaurosis but, in addition, we propose that augmented vasoconstrictor responses and vasospasm may contribute to amaurosis. In this study we tested the hypothesis that constrictor responses of retinal vessels to serotonin, which is released when platelets aggregate, are potentiated in experimental atherosclerosis. Blood flow to the retina was measured in normal and atherosclerotic cynomolgus monkeys. In normal monkeys, infusion of serotonin did not alter flow to the retina. In atherosclerotic monkeys, infusion of serotonin reduced retinal blood flow (in milliliters per minute per 100 g) from 66 +/- 7 (mean +/- SE) to 5 +/- 2. Infusion of serotonin in atherosclerotic monkeys abolished the retinal response to light. Thus, atherosclerosis greatly potentiates constrictor responses to serotonin in the retinal circulation and produces a profound but reversible impairment of retinal function. We propose that altered responses to vasoactive substances that are released by platelets may contribute to the pathogenesis of amaurosis fugax.

Animals↗