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Biomedical subjects

N Alexander

Publications and source records attributed to N Alexander.

At least 37 records · Page 2Linked to original sources
PubMed1996

Epithelioid sarcoma of the forearm.

A case of epithelioid sarcoma of the forearm is described. The radiological and pathological features, natural history of the tumour and its treatment are reviewed.

Adult↗
PubMed1996

Transmission dynamics of Wuchereria bancrofti in East Sepik Province, Papua New Guinea.

Bancroftian filariasis is endemic in many areas of Papua New Guinea. This study describes the entomologic indices of transmission near Dreikikir in East Sepik Province, Papua New Guinea. A total of 1,735 culicine mosquitoes, including Culex and Mansonia species, were dissected, but none were infected with filarial larvae. In contrast, Anopheles punctulatus and An. koliensis were found to be potential vectors: 7.3% of Anopheles were infected and the mean number of first- to third-stage larvae per infected mosquito was 2.7. Transmission indices varied significantly in five villages located within a 50-km radius of each other. Annual biting rates ranged from 4,789 to 48,020 bites/person/year; annual infective biting rates from 15 to 836/person/year; and annual transmission potential from 31 to 2,340 third-stage larvae/person/year. Monthly transmission potential and monthly infective biting rate varied significantly in each village, with the highest indices of transmission observed in villages nearest sites where puddles formed in river beds during the dry season. These data indicate that there is small area variation in the intensity and temporal pattern of filariasis transmission and that culicine mosquitoes are not important vectors of W. bancrofti in this area.

Animals↗
PubMed1995

Humoral and cell-mediated immunity to the Plasmodium falciparum ring-infected erythrocyte surface antigen in an adult population exposed to highly endemic malaria.

A parasitological and immunological survey was carried out in an area in Papua New Guinea highly endemic for malaria. Two hundred fourteen adult individuals were selected for studies to assess their immune responses against the malaria vaccine candidate ring-infected erythrocyte surface antigen (RESA). Total immunoglobulin G (IgG) antibodies directed against RESA as well as specific IgG1, IgG2, and IgG3 antibodies were determined. Humoral responses directed against RESA were frequent in all IgG subclasses. Only IgG3 responses were found to be age dependent. Total anti-RESA IgG antibodies were not correlated with protection against malaria as measured by parasite prevalence, parasite density, or health center attendance. In contrast, cytophilic antibodies (IgG1 and IgG3) were associated with reduced Plasmodium falciparum prevalence and reduced health center attendance. T-cell proliferation in general was low and very infrequent. No correlation between humoral and cellular immune responses could be found. Parasite density, parasite prevalence, and health center visits tended to be reduced in individuals with good humoral and cell-mediated immune responses.

Animals↗
PubMed1995

Flavoxate treatment of micturition disorders accompanying benign prostatic hypertrophy: a double-blind placebo-controlled multicenter investigation.

To investigate the effect of flavoxate (Urispadol) treatment on patients with symptomatic benign prostatic hypertrophy (BPH), with the main weight on the irritative symptoms, a randomized, double-blind, parallel-group, placebo-controlled and multicenter investigation was carried out. Seventy patients entered the study, 37 were allocated to flavoxate treatment on a daily dose of 1,200 mg (400 mg t.i.d.) for 12 weeks, and 33 patients were allocated to placebo treatment. In spite of a sufficient power, the study did not discriminate the two treatment groups in a statistically significant way (p > 0.05), when considering the main endpoints: the irritative symptom score and the global patient evaluation. Conservative treatment of micturition disorders accompanying BPH with flavoxate in doses of 1,200 mg/day cannot be recommended for clinical use.

Aged↗
PubMed1995

Evidence of HLA class II association with antibody response against the malaria vaccine SPF66 in a naturally exposed population.

The antibody response against the malaria vaccine SPf66 and against circumsporozoite (CS) protein has been tested in immune adults from a malaria endemic area in Papua New Guinea. All individuals were genotyped for the HLA class II DQB1 and DRB1 loci, and the humoral response was analyzed with respect to the identified class II alleles. At each locus, only three alleles were frequent, namely DRB1*11, *15, and *16, and DQB1*0301, *0502, and *0601. Antibodies against SPf66 and CS protein were found in 84% and 79% of the individuals, respectively. A strong negative association was detected between the humoral response against SPf66 and DRB1*15 and DQB1*0601. A positive association of the response was observed with DRB1*11 and DQB1*0301. After analysis with a multiple regression model in which all alleles were included simultaneously, only DRB1*15 remained significantly associated with low antibody responses. This suggests that nonresponders may be expected after immunization with SPf66 in certain populations.

Adolescent↗
PubMed1994

Assessment of the humoral and cell-mediated immunity against the Plasmodium falciparum vaccine candidates circumsporozoite protein and SPf66 in adults living in highly endemic malarious areas of Papua New Guinea.

To assess natural immunity against the circumsporozoite (CS) protein and the synthetic vaccine SPf66, immunologic studies were carried out in a highly endemic malarious area of Papua New Guinea. Antibody prevalence, antibody titers, and T cell proliferation against both antigens were measured in 214 adults. Immunologic data were analyzed with respect to longitudinal malariologic and morbidity data. Evidence of genetic traits such as glucose-6-phosphate dehydrogenase deficiency and ovalocytosis was analyzed. Antibody prevalence was high, with 79% and 84% for CS protein and SPf66, respectively, while T cell proliferation was infrequent and low, with 14% and 12% responders, respectively. Anti-CS protein antibodies increased with age but showed no association to malaria indices or morbidity. No protective value was observed with T cell responses or with humoral response to SPf66. These results provide a first description of naturally developed immunity against SPf66 and suggest further studies in to fully understand the mechanism of immunity against this antigen.

Adolescent↗
PubMed1994

Total knee arthroplasty after failed high tibial osteotomy.

Total knee arthroplasty performed after failed high tibial osteotomy is an important subgroup encompassing close to 10% of replacements performed and may be difficult in 20% to 40% of these patients. The problems in this group can be different from those encountered with primary of revision total knee arthroplasty. The authors present a review of the literature on this subject including assessments of variables affecting outcome. Preoperative clinical and radiographic factors to be considered are discussed and surgical technical factors are delineated.

Humans↗
PubMed1993

Cardiovascular change and hypothalamic norepinephrine release in response to environmental stress.

The major objective of this study was to compare the magnitude and duration of cardiovascular (CV) responses to acute environmental stresses with the associated patterns of noradrenergic activity in the paraventricular nucleus (PVN) and posterior nucleus (PH) of the hypothalamus. Simultaneous microdialysis samples of extracellular norepinephrine (NE) were collected at 5-min intervals from PVN and PH and the CV responses were recorded before, during, and for 15 min after acute shaker (cage oscillation) stress or inhalation of ether vapor in freely moving rats. Five minutes of shaker stress, 60 and 150 cycles/min, elicited pressor responses coupled with increases in dialysate NE from both PVN and PH in a frequency-dependent manner. Tachycardia occurred at 150 but not 60 cycles/min. Ten minutes after 60 cycles/min and 15 min after 150 cycles/min, NE efflux in PH was still increased, whereas in PVN it returned to control as had arterial pressure and heart rate. Ether vapor elicited a transient CV response but a continuing efflux of NE in PH and PVN. Urethan anesthesia raised baseline values of dialysate NE in PH and PVN but significantly attenuated cardiovascular and dialysate NE responses to shaker stress. We conclude that acute environmental stress simultaneously elicits CV responses and the efflux of NE from PVN and PH but, during or after stress, CV values may return to control levels while NE efflux remains elevated in PVN and/or PH.

Administration, Inhalation↗
PubMed1992

The long protocol of administration of gonadotropin-releasing hormone agonist is superior to the short protocol for ovarian stimulation for in vitro fertilization.

OBJECTIVE: To investigate whether pituitary desensitization with the gonadotropin-releasing hormone agonist (GnRH-a), buserelin acetate, before the administration of human menopausal gonadotropin (hMG) for ovarian stimulation in in vitro fertilization (IVF) is superior to the simultaneous administration of both hormones at the beginning of the treatment cycle. DESIGN: Prospective randomized study. PATIENTS: Ninety-one patients having their first attempt at IVF. INTERVENTIONS: Patients in group 1 (long protocol) were administered subcutaneous (SC) buserelin acetate 200 micrograms/d from day 1 of the menstrual cycle, and hMG was started only after pituitary desensitization had been achieved at least 14 days later. Patients in group 2 (short protocol) were administered SC buserelin acetate 200 micrograms/d from day 2 and the same dose of hMG used in the long protocol from day 3 of the menstrual cycle. RESULTS: The median total amount of hMG required in both groups was comparable. There were significantly more follicles (P = 0.0001), oocytes (P = 0.0008), fertilized oocytes (P = 0.0001), and cleaved embryos (P = 0.0001), and a higher fertilization rate (P = 0.0047) in patients in group 1. The pregnancy rates per initiated cycle and per embryo transfer were 19.57% and 25.71% in group 1 compared with 8.89% and 16.67% in group 2. CONCLUSIONS: The long protocol is superior in terms of significantly greater follicular recruitment, oocyte recovery and fertilization rates, and significantly greater number of embryos available for transfer. In general, it is the preferred method when GnRH-a are used for ovarian stimulation in IVF.

Adult↗
PubMed1992

Adjustment for the influence of age and heart rate on Doppler measurements of left ventricular filling.

OBJECTIVE: To determine the normal range of pulsed Doppler measurements of left ventricular filling adjusted for age and heart rate. DESIGN: Multiple regression was used to measure the effects of age and heart rate on pulsed Doppler indices of left ventricular filling in normal subjects. These regression equations were used to calculate a predicted normal value and 95% confidence interval (95% CI) for any subject from his age and heart rate. PARTICIPANTS: 61 subjects with no evidence of cardiovascular disease, aged 20 to 90 years, with a resting heart rate of 47-89 beats/min. RESULTS: The effect of a 10 year increase in age was peak atrial filling velocity +15% (95% CI 12.0% to 18.5%); peak early filling velocity -3.2% (-6.0% to 0%); isovolumic relaxation time +6.2% (3.9% to 8.4%); acceleration time -3.8% (-6.0% to -1.5%); deceleration time +7.9% (5.1% to 10.8%). The effect of a 10 beat/min increase in heart rate was: peak atrial filling velocity +5.5% (1.2% to 10.1%); peak early filling velocity -4.0% (-8.1% to 2.0%); isovolumic relaxation time -2.5% (-4.6% to 0.6%); acceleration time -3.1% (-6.4% to 0.4%); deceleration time -1.8% (-4.0% to 3.8%). CONCLUSION: For any individual, comparison of the predicted normal measurement and 95% CI with the observed measurement allows an assessment of the effects of disease on left ventricular filling that is independent of age and heart rate.

Adult↗
PubMed1991

Gastrin-releasing peptide gene products in midtrimester human fetal lung with and without maternal smoking history during pregnancy.

A preliminary morphological study on human fetal lungs with positive maternal smoking history demonstrated alterations of the neuroepithelial bodies (NEBs). We studied human fetal lung tissue between the gestational ages of 12 weeks and 19 weeks, comprising 12 cases with a smoking history during pregnancy (Group 1) and eight cases without a smoking history during pregnancy (Group 2). We demonstrated, by immunocytochemistry, the presence of gastrin-releasing peptide (GRP) gene products: GRP 14-27 in all 20 cases, and C terminal peptide of pro-GRP (C-flanking peptide) in 17 cases. Quantification of the neuroepithelial cells (NECs) was made by computer-enhanced image analysis using the Context Vision system, expressing 1) the total stained areas of the NECs per unit area of section and 2) the total staining areas of the NECs per unit area of airway epithelium, measured as the area of cytokeratin immunoreactivity in an adjacent section. The results show no statistically significant difference between groups 1 and 2 for either GRP 14-27 or C-flanking peptides. The apparent lack of influence of maternal smoking during pregnancy on the expression of GRP gene products in the NECs could be a reflection of inherently reduced reactivity of the cells during the gestation period studied. However, a larger series is needed before any conclusions can be made. Alternatively, the adverse effects of smoking might be reflected during the canalicular phase of lung development; an increased immunoreactivity appears to be present during that period. The expression of pro-GRP gene products in the pulmonary NECs of older fetuses and neonates with maternal smoking history during pregnancy requires further study.

Female↗