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Biomedical subjects

M Wood

Publications and source records attributed to M Wood.

At least 145 records · Page 8Linked to original sources
PubMed1995

Attenuation of isoproterenol-mediated vasodilatation in blacks.

BACKGROUND: The mechanism of enhanced vascular reactivity in young blacks, which may play a part in the development of hypertension, has not been defined. To determine the contribution of blunted vasodilatation mediated by beta 2-adrenergic receptors to this phenomenon, we compared forearm blood-flow responses to isoproterenol in young black and white normotensive men. METHODS: We used venous-occlusion plethysmography to measure the responses of blood flow in the forearm to the intraarterial administration of isoproterenol (10 to 400 ng per minute) in 9 normotensive black men (mean [+/- SD] age, 31.3 +/- 8.0 years) and 13 normotensive white men (mean age, 32.9 +/- 5.6 years). Sympathetic activity in the forearm was measured simultaneously by isotope-dilution techniques. RESULTS: Base-line blood flow in the forearm was similar in blacks and whites, but the degree of vasodilatation in response to isoproterenol was markedly lower in blacks. Isoproterenol at an infusion rate of 400 ng per minute produced a 9-fold increase in blood flow in whites but only a 3.5-fold increase in blacks (P < 0.001). The base-line rate of norepinephrine spillover in the forearm was higher in blacks (2.0 +/- 1.3 ng per minute [11.8 +/- 7.7 nmol per minute]) than in whites (0.6 +/- 0.5 ng per minute [3.5 +/- 3.0 nmol per minute], P = 0.002), but there was no difference between the groups after isoproterenol stimulation. CONCLUSIONS: Forearm blood-flow responses to isoproterenol were markedly attenuated in normotensive blacks, indicating a blunting of vasodilatation mediated by beta 2-adrenergic receptors. Sympathetic activity in the forearm was greater in blacks than in whites, but isoproterenol-stimulated presynaptic beta 2-adrenergic responses (which facilitated norepinephrine release) did not differ significantly between blacks and whites. Our findings suggest that the mechanisms responsible for blunted vasodilatation in response to the administration of isoproterenol may contribute to enhanced vascular reactivity in blacks and may play a part in the pathogenesis of hypertension in blacks.

Adult↗
PubMed1995

A controlled trial of povidone-iodine as prophylaxis against ophthalmia neonatorum.

BACKGROUND: Neonatal conjunctivitis (ophthalmia neonatorum) continues to cause blindness because the agents used prophylactically to prevent this condition are not completely effective and are not widely available in many parts of the world. Povidone-iodine ophthalmic solution is an effective antibacterial agent with broad antibacterial and antiviral activity to which no bacteria are known to be resistant, and it is far less expensive and less toxic than the agents currently used to prevent neonatal conjunctivitis. METHODS: We conducted a masked, prospective trial involving 3117 infants born over a period of 30 months in a hospital in Kenya. Shortly after birth each infant received a 2.5 percent solution of povidone-iodine (n = 1076), a 1 percent solution of silver nitrate (n = 929), or 0.5 percent erythromycin ointment (n = 1112) in both eyes. Randomization was achieved by rotating the three medications after each was used for a week. RESULTS: Of the neonates treated with povidone-iodine, 13.1 percent had infectious conjunctivitis, as compared with 17.5 percent of those treated with silver nitrate (P < 0.001) and 15.2 percent of those treated with erythromycin (P = 0.01). Povidone-iodine was more effective against Chlamydia trachomatis than was silver nitrate (P < 0.001) or erythromycin (P = 0.008). There were 104 cases of noninfectious conjunctivitis (9.7 percent) in the povidone-iodine group, as compared with 129 in the silver nitrate group (13.9 percent, P < 0.001) and 148 in the erythromycin group (13.3 percent, P = 0.004). Many cases of noninfectious conjunctivitis were probably due to a toxic reaction to the treatment itself. The incidence of Neisseria gonorrhoeae and Staphylococcus aureus infections was similar in the three groups. CONCLUSIONS: A 2.5 percent ophthalmic solution of povidone-iodine as prophylaxis against ophthalmia neonatorum is more effective than treatment with silver nitrate or erythromycin, and it is less toxic and costs less.

Erythromycin↗
PubMed1995

Dietary sodium intake modulates systemic but not forearm norepinephrine release.

INTRODUCTION: Sodium intake has profound effects on systemic and renal sympathetic activity, but its effects on sympathetic activity in skeletal muscle vascular beds, a site at which local regulatory mechanisms could alter vascular tone directly, are unclear. METHODS: To determine the effect of dietary sodium intake on basal and isoproterenol-stimulated systemic and forearm norepinephrine kinetics, we studied seven healthy male volunteers twice, 4 weeks apart, while they were receiving a low-sodium (10 mmol sodium/24 hours) diet and a high-sodium diet (250 mmol sodium/24 hours). Forearm blood flow, measured by plethysmography, and systemic and forearm norepinephrine spillover, measured by radioisotope dilution, were determined before and after intra-arterial infusion of 60 and 400 ng/min isoproterenol. RESULTS: Baseline (before isoproterenol) systemic norepinephrine spillover was higher when subjects received the low-sodium diet (448.1 +/- 55.7 ng/min) compared with the high-sodium diet (269.7 +/- 42.7 ng/min; p < 0.05). In contrast, sodium intake did not affect local forearm norepinephrine spillover, either at baseline (low-sodium diet, 2.05 +/- 0.48 ng/min versus high-sodium diet, 2.63 +/- 0.79 ng/min; p = 0.50) or after stimulation with isoproterenol in doses of 60 ng/min (low-sodium diet, 8.84 +/- 2.2 ng/min versus high-sodium diet, 6.1 +/- 1.9 ng/min; p = 0.38) or 400 ng/min (low-sodium diet, 16.4 +/- 4.5 ng/min versus high-sodium diet, 16.7 +/- 2.5 ng/min; p = 0.93). CONCLUSIONS: Under conditions of low sodium intake, systemic norepinephrine spillover was increased but forearm norepinephrine spillover was not, suggesting that alteration in sodium intake may produce a differential effect on norepinephrine spillover in different tissues but that decreased local sympathetic activity in skeletal muscle is not the likely mechanism by which a low-sodium diet may lower blood pressure or attenuate stress-induced pressor responses.

Adrenergic beta-Agonists↗
PubMed1995

Intraneural perineurioma. A clonal neoplasm associated with abnormalities of chromosome 22.

The nature of perineurioma, variably termed "localized hypertrophic neuropathy," "intraneural neurofibroma," and "hypertrophic interstitial neuritis" has long been an issue of contention. Most authors consider it a neoplasm, but some a reactive process. Eight clinically and morphologically typical perineuriomas were studied by histologic, immunohistochemical and ultrastructural methods. One perineurioma was subject to tissue culture and cytogenetic study and another to fluorescence in situ hybridization (FISH) analysis. The patients, 3 males and 5 females, ranged in age from 11 to 38 years. All tumors were intraneural, and involved extremities (2 sciatic, 1 median, 1 femoral, 1 peroneal, 1 brachial plexus, 1 ulnar, and 1 radial). Neurologic symptoms, motor in all cases and sensory in 4, were present from 1 month to 7 years (mean 1.2 years). Fusiform, segmental nerve enlargement was clinically apparent in only two patients, but was evident on MRI in five of eight patients. Lesion length ranged from 3.5 to 30 cm, the largest involving the sciatic nerve from the obturator foramen to the knee. One lesion involved two nerve roots, but no association with a phakomatosis was noted. Treatment consisted of biopsy in six cases and resection in two cases. Histologically, pseudo-onion bulbs composed of epithelial membrane antigen-reactive, S-100 protein-negative perineurial cells surrounded myelinated or nonmyelinated nerve fibers. Many were accompanied by their S-100 protein-positive Schwann sheaths. Some whorls lacked a central axon. A single mitosis was noted in one case. The MIB-1 antigen labelling index ranged from 4% to 17%. Staining for p53 antigen in six cases showed no (2 of 6), rare (2 of 6), or scattered (2 of 6) immunoreactive nuclei. Cytogenetic analysis in one case demonstrated a chromosomally abnormal clone. Each of 16 metaphases was abnormal; the tumor cells appeared to be homozygously deficient for the region 22q11.2qter. In another case, 53% of interphase nuclei showed three FISH signals with a chromosome 14/22 probe, thus suggesting either monosomy for the centromere of chromosome 14 or that of chromosome 22.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1995

Chemopreventive activity of Oltipraz against N-nitrosobis(2-oxopropyl)amine (BOP)-induced ductal pancreatic carcinoma development and effects on survival of Syrian golden hamsters.

The synthetic dithiolethione Oltipraz has marked cancer chemopreventive and phase II enzyme inducing activity in various animal carcinogenesis models, but has not been examined in any animal models of ductal pancreatic cancer relevant to the human disease. The chemopreventive potential of Oltipraz on pancreatic tumor incidence and multiplicity was examined in the N-nitrosobis(2-oxopropyl)-amine (BOP)-induced ductal pancreatic adenocarcinoma model in Syrian hamsters. Animals were maintained on control semipurified diets or semipurified diets containing 300 and 600 mg/kg Oltipraz beginning 2 weeks prior to BOP initiation and throughout the 26 week study. Oltipraz at 300 mg/kg had no effect on the incidence or multiplicity of preneoplastic, neoplastic or metastatic lesions, while at 600 mg/kg dietary Oltipraz the incidence of pancreatic adenocarcinomas was reduced significantly (P < or = 0.05) compared to BOP-treated controls. Dietary Oltipraz at both doses had a significant influence on reducing mortality and morbidity in tumor-bearing animals with metastatic disease. At 26 weeks, total hepatic glutathione-S transferase (GST) activity and GST mu activity were elevated significantly in Oltipraz-treated animals, while total pancreatic GST activity was reduced, albeit not significantly. Serum lipase activity, a marker for pancreatic damage, exhibited a progressive decline in BOP-treated animals administered Oltipraz compared to BOP-treated controls at 12 weeks of the study; by week 26, lipase activity was comparable in all groups and reduced compared to activity at week 12. Positive nuclear immunostaining for the p53 tumor suppressor protein, a hallmark of human pancreatic cancer and a transient response to DNA damage, was observed in only a small percentage of BOP-induced pancreatic lesions and was not influenced Oltipraz administration. Further chemoprevention and pharmacologic studies of Oltipraz in relevant animal models of ductal pancreatic cancer could provide a foundation for future studies in human populations at potential risk for pancreatic cancer.

Animals↗
PubMed1995

Regulation of norepinephrine release by beta 2-adrenergic receptors during halothane anesthesia.

BACKGROUND: Presynaptic receptors control norepinephrine (NE) release. It has been hypothesized that epinephrine stimulates prejunctional beta 2-adrenergic receptors to facilitate NE release from sympathetic nerve endings, and therefore, presynaptic receptors controlling NE release are potential therapeutic targets to limit the adverse effects of excess sympathetic stimulation during anesthesia. We have previously demonstrated beta 2-adrenergic receptor-augmented release of NE in the human forearm and have shown that halothane inhibits sympathetic activity in vivo by decreasing the NE spillover rate into plasma. The goal of the current study was to determine the effect of halothane on beta 2-adrenergic receptor-augmented NE release in a canine hind-limb experimental model. METHODS: Seven female dogs were studied awake and during halothane anesthesia (1.0 minimum alveolar concentration). A trace dosage of [3H]NE (15 microCi over a 1-min period and 0.6 microCi/min thereafter) was infused into the femoral vein. Before and during femoral arterial administration of isoproterenol at two dosages (30 and 80 mg/min), hind-limb blood flow was measured by an ultrasonic flow probe and hind-limb NE spillover by an isotope dilutional technique. RESULTS: In awake dogs, isoproterenol significantly increased hind-limb blood flow and NE spillover into the hind limb. Halothane had no effect on baseline or isoproterenol-stimulated hind-limb blood flow (a postjunctional beta 2 effect) but significantly inhibited the isoproterenol-induced increase in hind-limb NE spillover (a prejunctional beta 2 effect). CONCLUSIONS: The isoproterenol-mediated increase in NE release is inhibited by halothane anesthesia, indicating that halothane inhibits prejunctional beta 2-adrenergic receptor regulation of NE release.

Anesthesia↗
PubMed1995

Dietary sodium intake modulates vasodilation mediated by nitroprusside but not by methacholine in the human forearm.

Studies in animals suggest that nitric oxide production is increased under conditions of salt loading and that this increase protects against the development of salt-induced hypertension. To determine the effect of dietary sodium intake on nitric oxide-mediated vascular responses, we studied seven healthy male volunteers twice 4 weeks apart while they were receiving a diet containing 10 or 250 mmol Na+ per 24 hours. Methacholine (0.25 to 8 micrograms/min) and sodium nitroprusside (0.25 to 8 micrograms/min) were infused intra-arterially in incremental doses, and forearm blood flow was measured. The response of forearm blood flow to sodium nitroprusside was greater when subjects received a high sodium diet than when they received a low sodium diet (F = 7.11, P < .05); however, the response to methacholine was not altered by sodium intake (F = 0.57, P = NS). Plasma renin activity was significantly higher (3.99 versus 1.0 ng angiotensin I/mL per hour) when subjects received a low salt diet (P < .05). Systolic pressure, diastolic pressure, heart rate, and baseline forearm blood flow were not affected by sodium status. We conclude that under conditions of salt loading, vasodilation in response to sodium nitroprusside was enhanced, whereas the response to methacholine was not affected, suggesting a differential effect of sodium intake on endothelium-dependent and endothelium-independent responses after the administration of methacholine and sodium nitroprusside, respectively.

Adult↗
PubMed1995

Tachyphylaxis of human forearm vascular responses does not occur rapidly after exposure to isoproterenol.

In vitro and limited in vivo data suggest that rapid desensitization of beta-adrenoceptor responses occurs after exposure to agonist. Tachyphylaxis to a beta-adrenoceptor agonist would represent a potentially important mechanism for the short-term regulation of vascular tone. The effects of a 4-hour infusion of 400 ng/min intra-arterial isoproterenol on forearm blood flow and presynaptic beta-adrenoceptor-mediated norepinephrine release were determined in eight healthy volunteers. Intra-arterial isoproterenol at 400 ng/min resulted in a significant increase in forearm blood flow in all eight subjects at all time points, with no evidence of tachyphylaxis. In fact, forearm blood flow after 4 hours of the isoproterenol infusion (22.8 +/- 3.3 mL/100 mL per minute) was significantly greater than after 7 minutes (14.6 +/- 2.8 mL/100 mL per minute), 15 minutes (15.4 +/- 2.4 mL/100 mL per minute), and 30 minutes (17.4 +/- 3.0 mL/100 mL per minute) of the infusion (P < .05). Similarly, presynaptic beta-adrenoceptor responses showed no evidence of tachyphylaxis, so forearm norepinephrine spillover values after 7 minutes (6.6 +/- 0.94 ng/min), 15 minutes (7.6 +/- 1.5 ng/min), and 4 hours (8.8 +/- 1.1 ng/min) of isoproterenol infusion were increased and similar. Minimal systemic effects were observed, and there was no evidence of tolerance, there being no difference in heart rate after 7 minutes (70.7 +/- 2.7 beats per minute) and 4 hours (72.2 +/- 3.6 beats per minute) of isoproterenol infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Forearm beta adrenergic receptor-mediated vasodilation is impaired, without alteration of forearm norepinephrine spillover, in borderline hypertension.

Impaired beta adrenoceptor-mediated vasodilation associated with enhanced sympathetic activity has been reported in established hypertension. We examined whether altered beta adrenoceptor-mediated vasodilation occurs early in the disease process, when structural vascular changes are likely to be less marked, by measurement of forearm blood flow by strain gauge plethysmography after the intraarterial administration of increasing doses of a beta receptor agonist, isoproterenol, in eight subjects with borderline hypertension (BHT) and 13 normotensive (NT) controls. To determine the role of sympathetic activation in the regulation of responsiveness, we measured local sympathetic activity in the forearm by a radioisotope dilution technique. Vasodilation in response to isoproterenol, measured either as changes in forearm blood flow or forearm vascular resistance, was impaired in the BHT group so that flow at the highest dose of isoproterenol (400 ng/min) increased less (15.2 +/- 1.5 ml/100 ml per min) than in the NT group (24.4 +/- 2.4 ml/100 ml per minute) (P < 0.001). Although, systemic norepinephrine spillover was significantly greater in BHT, the difference in blood flow response to isoproterenol was not accounted for by increased local sympathetic activity since forearm norepinephrine spillover at baseline (BHT 1.0 +/- 0.4 ng/min vs. NT 0.64 +/- 0.13 ng/min) and after the administration of isoproterenol 60 ng/min (BHT 5.2 +/- 1.4 ng/min vs. NT 6.0 +/- 1.5 ng/min) and 400 ng/min (BHT 13.5 +/- 2.9 ng/min vs. NT 16.5 +/- 2.7 ng/min) did not differ between the two groups. We therefore conclude that vasodilation in response to isoproterenol is impaired in subjects with BHT and that this impairment is not explained by locally increased basal, or stimulated, sympathetic activity.

Adult↗
PubMed1995

10-year periodontal response to resin bonded bridges.

The purpose of this study was to evaluate the long-term (10 years +/- 15 months) periodontal response to resin bonded bridges (RBRs). A total of 103 patients who had RBRs bonded between 1980 and 1984 were recalled. Periodontal evaluations were made by two clinicians for all abutment teeth and for selected control teeth with intact, non-restored lingual surfaces. Periodontal indices consisted of: plaque index (PI), gingival index (GI), gingival recession, probing depth, and loss of attachment. Paired t tests indicated no significant difference in overall GI between experimental and control sites, but a significant difference in PI and probing depth with experimental sites (abutment teeth) showing higher PI and greater probing depths. Significant differences were found in overall recession and attachment loss, again with more recession and attachment loss observed on the abutment teeth as compared to the controls. Site specific analyses for PI, probing, and loss of attachment showed small but significant differences between experimental and control teeth in 15 of 21 sites. Although these findings may be statistically significant, the clinical impact for resin bonded restorations functioning for over 10 years is minimal and is comparable to periodontal response to other types of restorations.

Analysis of Variance↗
PubMed1995

Causes of childhood blindness in east Africa: results in 491 pupils attending 17 schools for the blind in Malawi, Kenya and Uganda.

Pupils attending 12 schools for the blind in Malawi, 3 schools in Kenya and 2 schools in Uganda were examined to determine the causes of severe visual impairment or blindness (visual acuity in the better eye of less than 6/60). A total of 491 pupils aged 3-22 years was examined. Visual acuity was measured in each eye using a Snellen E chart. The anatomical site of abnormality and underlying cause of visual loss were determined by clinical examination for each eye, and for the child. Information was recorded on a standard reporting form (the WHO/PBL Eye Examination Record for Children with Blindness and Low Vision). Data were analysed for those aged less than 16 years using a database which accompanies the form. Preventable and treatable causes were identified. 260 pupils aged 5-20 years were examined in Malawi, 163 pupils aged 3-19 years were examined in Kenya and 68 pupils aged 6-22 years were examined in Uganda. Of the 491 students included in the study 309 (62.9%) were blind (BL) and 69 (14.1%) were severely visually impaired (SVI). 244 were aged less than 16 years and had SVI/BL. In these 244 children 35.2% of visual loss was due to corneal pathology, 13.5% was due to cataract and 14.8% to diseases of the retina. Corneal pathology, attributed to vitamin A deficiency and measles infection in the majority, was responsible for proportionally more SVI/BL in students in Malawi than in Uganda or Kenya.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Tourist health services at tropical island resorts.

An unfamiliar holiday environment may give rise to a range of common and unique medical conditions and injuries. Based on a six-month retrospective analysis of clinic records, the present study reports a detailed profile of health services provided for guests at three tropical island tourist resorts. A total of 1183 clinic visits were analysed; 735 (62 per cent) concerned medical conditions, while 448 (38 per cent) were related to injuries. The most common medical conditions treated were respiratory, digestive, skin problems, eye disorders, and genito-urinary complaints. Injuries included lacerations, bites and stings, sprains and fractures. Health services consisted mainly of medication, specialist nursing care and first aid. Study findings highlight the advantages of using an internationally accepted classification system for primary health research, and the critical role of the nurse in tourist health services.

Australia↗
PubMed1995

One-stage primary repair of distal esophageal perforation using fundic wrap.

Esophageal leak following primary repair of esophageal perforation is a serious complication that can lead to severe mediastinitis and sepsis. Complete diversion with esophageal exclusion or resection is designed to minimize further mediastinal contamination. However, this approach is not necessarily associated with less morbidity or mortality. Furthermore, a second stage operation is required to restore esophageal continuity. From 1986 to 1994, we performed a one-stage primary repair of the distal esophagus in seven patients with either iatrogenic (n = 5) or spontaneous (n = 2) perforations and reinforced the repair by a fundic wrap. One patient underwent an additional modified Heller myotomy for achalasia. Delay between perforation and operation was less than 6 hours in 3 patients, 6 to 24 hours in 2 patients, and greater than 24 hours in 2 patients. Only one patient (14%) developed a small esophageal leak that spontaneously resolved with adequate mediastinal drainage, intravenous antibiotics, and aggressive nutritional support. One patient (14%), whose repair was delayed by 12 hours, died postoperatively of profound sepsis. This patient was moribund from sepsis preoperatively, and postmortem examination of the esophagus revealed no evidence of esophageal leak. Esophageal continuity was maintained in all patients. The median length of stay was 21 days (range, 15-58 days). We conclude that primary reinforced repair of esophageal perforation using a fundic wrap is an effective method of treatment for distal esophageal perforation, even when the repair is delayed by more than 24 hours.

Adult↗
PubMed1995

Physician directed networks: the Renaissance perspective.

It is time for all providers, physicians, hospital executives and ancillary providers to find creative ways to meet the healthcare needs of their local communities. More efficient systems of health care delivery will come from noncompetitive partnerships based on shared visions, collaborations, openess, honesty and integrity. RHP can be a catalyst for physicians and other providers in the Kansas City area and throughout the state to respond to the challenges and opportunities that lie before them.

Community Health Services↗