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Biomedical subjects

C Henderson

Publications and source records attributed to C Henderson.

At least 91 records · Page 5Linked to original sources
PubMed1993

Twin gestation: fetal presentation as a function of gestational age.

OBJECTIVE: Our objective in this study was to evaluate the rate of spontaneous version in twin gestation throughout the third trimester. STUDY DESIGN: Serial ultrasonographic examinations were performed on 119 consecutive patients with twin gestation. The incidence of spontaneous version as a function of gestational age was calculated. RESULTS: The mean birth weight and gestational age at delivery were 2640 gm and 37 weeks, respectively. Nineteen percent had birth weight discordancy, and 37% were delivered by cesarean section. The incidence of spontaneous version decreased from 60% at 28 to 30 weeks' gestation to 25% to 30% at term. The lowest incidence of spontaneous version was observed in pregnancies with a cephalic-cephalic presentation (7%). All other presentations were relatively unstable. Neither the patients' parity nor the presence of birth weight discordancy, the placental location, or the amniotic fluid volume had a significant association with the incidence of spontaneous version. CONCLUSION: These data should be incorporated into the routine antepartum counseling of patients with twin gestation. Their use in this capacity may result in a decreased cesarean delivery rate if clinicians realize that malpresentations may spontaneously resolve before the onset of labor.

Adolescent↗
PubMed1991

A Canadian model for developing mental health services in rural communities through linkages with urban centers.

The development of mental health care services in rural areas has been a constant challenge in most countries of significant geographical size. By use of a case study from Canada, the development of a relationship between rural and urban mental health services was described. Issues including referral patterns, service accessibility, professional recruitment and the development of service in rural regions were studied. It is advanced that mental health administrators, policy-makers, clinical service coordinators and educators will find that this approach to the development of mental health services in rural areas has some utility in Canada and in other countries.

Canada↗
PubMed1991

Neodymium:YAG laser damage to UV-absorbing poly(methyl methacrylate) and UV-absorbing MMA-HEMA-EGDMA polymer intraocular lens materials.

MemoryLenses and UV-poly(methyl methacrylate) intraocular lenses, which served as controls, were individually exposed to twenty 5 mJ shots of the Nd:YAG laser focused onto the posterior surface while placed in a sterile holder containing 5 ml of saline. The MemoryLens is a new foldable intraocular lens (IOL) manufactured from a polymer consisting of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethyacrylate (EGDMA) with a UV absorber. Damage to the lenses was assessed by scanning electron microscopy. Cytotoxicity tests designed to detect potentially toxic substances released during laser damage were conducted with the saline solution by incubating it with mouse fibroblasts. Additional tests of the saline solution were conducted by high performance liquid chromatography and spectrophotometry. Damage induced by the Nd:YAG laser to the UV-poly(methyl methacrylate) IOLs was similar to that reported by other authors. Damage to the MemoryLens appeared less severe and showed no radial stress cracking. Cytotoxicity tests were negative for both types of IOLs. High performance liquid chromatography tests were negative for residual monomers (MMA, HEMA, EGDMA) and spectrophotometry did not reveal residual UV absorber.

Animals↗
PubMed1991

Serum time curve characteristics of a fixed dose of beta-carotene in young and old men.

The present study was designed to evaluate age-related differences in serum beta-carotene time curve response characteristics when a beta-carotene dose was given in conjunction with 1500 kcal over the course of a day. On two consecutive days, seven old (73 +/- 4 years) and six young (24 +/- 1 years) men were each fed three 500-kcal meals of an isotonic liquid formula diet containing only trace amounts of beta-carotene. On the first day of testing, no supplemental beta-carotene was given (baseline day). A 15 mg dose of beta-carotene was fed with the morning meal on the second day (test dose day). Fasting blood and hourly blood samples were obtained for 8 consecutive hours on both days. Additional blood was drawn 24 and 48 hours after the test beta-carotene dose. There were no statistical differences in baseline beta-carotene concentrations between the two age groups tested, but, because of high individual variability, serum time curve characteristics were adjusted for fasting beta-carotene levels. After adjustment, the postdose serum beta-carotene response was two to three times greater (p less than or equal to 0.04) in young subjects, as evaluated by peak concentration, area under the curve, or ascending slope of the serum response curve. Examination of factors besides age group that may have accounted for these results suggests that the serum response of the elderly may be more a function of body composition and/or serum lipid patterns than of age per se. However, in the present US population, it may not be valid to control for these factors, which are both closely related to aging.

Adult↗
PubMed1991

Efficacy of polyacrylamide vs. sodium hyaluronate in cataract surgery.

A prospective randomized study was conducted in 137 patients who underwent cataract surgery and implantation of a polymethylmethacrylate intraocular lens with either polyacrylamide (Orcolon) (68 patients) or sodium hyaluronate (Healon) (69 patients) as the viscoelastic material. Both viscoelastics were aspirated at the end of surgery. Patients were examined before surgery and 1 and 14 days after surgery. Endothelial cell counts were obtained before surgery and 3 months after surgery in 34 patients (16 in the polyacrylamide group and 18 in the sodium hyaluronate group). There were no reports of a flat or shallow anterior chamber intraoperatively in either group. There was no statistically significant difference between the two groups in the incidence of corneal edema or iritis on any visit or in endothelial cell loss. Although there was a significant reduction in intraocular pressure across postoperative visits for the overall sample, there was no significant difference in pressure between the polyacrylamide and sodium hyaluronate groups. The results indicate that no untoward effects on corneal edema, endothelial cell count, iritis or intraocular pressure are to be expected when polyacrylamide is used as an aid to cataract surgery.

Acrylic Resins↗
PubMed1990

Pregnancy outcomes among mothers infected with human immunodeficiency virus and uninfected control subjects.

Between June 26, 1985, and Feb. 24, 1989, 101 seropositive pregnant women and 129 seronegative pregnant women from the same prenatal clinics in Brooklyn and the Bronx were recruited into a prospective study of human immunodeficiency virus infection in pregnant women and their offspring. This report details the course of pregnancy and short-term neonatal outcomes of 91 seropositive women and 126 seronegative women who gave birth during the study period. Seropositive mothers were significantly more likely to have sexually transmitted diseases (17.6% vs 7.1%, p = 0.017) and medical complications (43.0% vs 25%, p = 0.006) during pregnancy. No other obstetric complications (e. g., chorioamnionitis, endometritis, toxemia, or placental problems) were associated with serologic status. After controlling for confounding variables (drug use, tobacco use, age of mother, and clinic), we found that the mother's serologic status was not significantly associated with birth weight, gestational age, head circumference, or Apgar scores among live infants. For example, after adjustment on confounders we found that children born to seropositive mothers weighed about 7 gm more than children of seronegative mothers (95% confidence interval, -180 to 194 gm). We conclude that in this population human immunodeficiency virus infection has little demonstrable impact on the status at birth of live neonates.

Adult↗
PubMed1989

In vitro stimulation of rat liver retinyl ester hydrolase by ethanol.

Retinyl ester hydrolase (REH), the enzyme which converts retinyl esters to retinol, was partially characterized from whole liver homogenates of rats using an HPLC method with quantitation of retinol product. Optimal results were obtained by incubation of 1 mg of whole homogenate protein with 900 microM all-trans-retinyl palmitate and 275 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate in a 0.1 M Tris-maleate buffer, pH 7.0, for 1 h at 37 degrees C. The enzyme assay proved to be sensitive and reproducible, with an interanimal coefficient of variation of 13% (n = 7). Because ethanol has been shown to mobilize vitamin A from the liver, we tested its effect on REH activity at several concentrations. In concentrations ranging from 0.01 to 0.5 M, ethanol added in vitro caused a concentration related increase in REH activity (from 20 to 86% above baseline activity). This increase was specific to ethanol as acetaldehyde, 1-propanol, and t-butanol either did not change or significantly decreased REH activity over the range of concentrations tested. The range of concentrations of ethanol causing stimulation in our assays was within the range of concentrations seen in the blood of rats after acute ethanol ingestion. Stimulation of REH activity could explain, in part, the well-known effects of ethanol on mobilization of vitamin A from liver stores.

Acetaldehyde↗
PubMed1989

Neonatal resuscitation in community hospitals. A regional-based, team-oriented training program coordinated by the tertiary center.

Neonatal resuscitation in community hospitals is problematic because of the lack of on-site personnel with adequate training and experience. Even when efforts are made to transport high-risk mothers to tertiary care centers, the most complex resuscitations must occasionally be performed in all obstetric services. This dilemma can result in increased neonatal morbidity and mortality, and is reflected in the obstetric malpractice crisis. We present an approach to the problem in which a tertiary center actively intervenes to assist regional community hospitals to develop and implement resuscitation team capabilities. Key aspects of the system are training and implementation of hospital shift "Code Pink" teams composed of nonphysician professionals, a regional neonatal resuscitation protocol used by all participants, "mock code" resuscitation drills to maintain skills, and extensive quality assurance both at the local hospital and regional levels.

Clinical Protocols↗
PubMed1989

Bone mineral content in postmenopausal women: comparison of omnivores and vegetarians.

This cross-sectional study of bone mineral content (BMC)/bone width (BW) (BMC/BW, cortical radius) was conducted in elderly, free-living Methodist omnivores (n = 146) and Seventh-day Adventist vegetarians (n = 144) in southern California. The purpose was to investigate relationships between BMC/BW and dietary factors (primarily vegetarianism and intakes of protein and calcium) and use of prescribed drugs. BMC was measured by single-photon absorptiometry. Dietary intakes during current and early periods of life were assessed by 24-h dietary recall and frequency methods. Information about drug use was obtained by interview. BMC/BW was not different in omnivores vs vegetarians. There were no significant relationships or trends between current or early dietary intakes and BMC/BW in either group. In multiple-regression analysis, age, weight, and use of estrogen and thiazide diuretics were predictive of 31% of the variability in BMC/BW in the total group.

Anthropometry↗
PubMed1988

Expression of the gangliosides GM3, GD3 and GD2 in tissue sections of normal skin, naevi, primary and metastatic melanoma.

Expression of the gangliosides GM3, GD3 and GD2 was studied in tissue sections from 19 naevi, 29 primary and 83 metastatic melanoma using the ABC immunoperoxidase technique. GM3 was not detected in normal skin whereas GD2 was detected on the basal and stratum spinosum of the epidermis and on peripheral nerves in the dermis. GD3 was expressed on melanocytes but not on most other components of normal skin. However, GD3 was strongly expressed on epidermis adjacent to naevi and primary melanoma whereas GD2, in contrast to that in normal skin, was not expressed on the epidermis adjacent to 26/29 primary melanoma. All naevi were positive for GM3 and GD3 except that GM3 was not detected on junctional components of naevi. GD2 was not expressed on naevi except in areas showing neuroid differentiation. Studies on melanoma revealed that approximately 60% of primary and 75% of metastatic melanoma expressed GM3 to a varying extent. With 2 exceptions, all primary and metastatic melanomas expressed GD3 although there was variable expression within most of the individual tumours. GD2 was detected in only approximately 25% of primary and 50% of metastatic melanomas. Both GD2 and GD3 were detected on lymphocytes surrounding melanoma. The higher expression of GD2 on metastases compared to primary melanomas was consistent with the view that GD2 expression was associated with increased metastatic potential. However, the low proportion of metastases expressing GD2 and the absence of any correlation with thickness of the primary tumour suggested that GD2 expression was not a reliable marker of metastatic potential. No differences could be detected in ganglioside expression on metastases in skin or lymph nodes. These results appear to have implications for the use of MAbs against gangliosides in therapy of melanoma and in the study of melanocytic differentiation.

Antigens↗
PubMed1988

Food and nutrient intake of Seventh-day Adventist women.

Dietary intake data were collected on Seventh-day Adventist vegetarian and Methodist omnivorous postmenopausal women living in the Los Angeles area: Both groups met the Recommended Dietary Allowances except for zinc, folate, vitamin B-6, and vitamin E. Vegetarians' diets had a somewhat higher nutrient density for folate, thiamin, vitamin C, and vitamin A; lower total fat, saturated fatty acids, and cholesterol; and higher dietary fiber. No correlation between dietary intake and bone mineral content was observed. These findings are compared with those in a study on Oregon vegetarian women.

Aged↗
PubMed1988

Suppression of natural killer cell activity in humans by radiation from solarium lamps depleted of UVB.

Previous studies have shown that ultraviolet radiation (UVR) from solarium lamps suppressed natural killer (NK) cell activity in the blood and that sunscreen lotions offered no protection against this effect. In the present study we tried to determine whether the effects on NK cell activity were caused by the UVB or the UVA components of radiation from solarium lamps by filtering out UVB with Mylar sheeting. Groups of 10 normal subjects were either left untreated or exposed for 30 min on 12 consecutive days to radiation that was filtered or not filtered through a 0.1 mm thick Mylar sheeting. NK cell activity was depressed in the group exposed to solarium radiation and this was not prevented by filtration through Mylar. The latter procedure, however, appeared to prevent changes in blood lymphocyte subsets that are induced by solarium radiation as well as the reduction in Langerhans cell numbers in skin biopsies taken after exposure to solarium radiation. Suppression of NK cell activity was evident up to 14 days after cessation of UVR exposure. This would be consistent with the replacement of NK cells from bone marrow that had been damaged as a result of direct effects of UVA on NK cells in the microcirculation of the skin or else indicate functional suppression of NK cells by suppressor cells induced by UVR as postulated for UVR-induced suppression of delayed hypersensitivity responses in murine models. These studies suggest that UVA may be important in the induction of certain effects on the immune system in human subjects. Further studies are required to assess the implications of these findings with respect to induction of neoplasia and the design of sunscreens effective against UVA.

Adult↗
PubMed1988

Auditory brainstem response in obstructive sleep apnea.

Auditory brainstem response (ABR) has been used by several investigators to study the role of the brain stem in the pathophysiology of obstructive sleep apnea (OSA). These studies have produced conflicting results. We studied 27 preoperative OSA patients and 17 controls using click stimuli presented at a slow (11.7/second) rate and at a fast (57.7/second) rate. ABR was repeated postoperatively in 18 patients. There were no statistically significant differences in the ABRs of preoperative OSA patients when compared with the control group. However, the preoperative recordings showed statistically significant prolonged latencies for wave III (p less than 0.01) and interpeak latency (IPL) I-III (p less than 0.01) when compared to postoperative recordings. Rapid-rate testing was not helpful. Although normal sleep does not cause ABR abnormalities, the pathological sleepiness seen in OSA patients may cause brainstem dysfunction manifested by prolonged ABR latencies. These abnormalities may resolve with treatment of OSA.

Adult↗