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Biomedical subjects

M E Nelson

Publications and source records attributed to M E Nelson.

At least 19 recordsLinked to original sources
PubMed1992

Prevalence of antibody titers to Leptospira spp. in Minnesota white-tailed deer.

Serum samples (n = 204) from 124 white-tailed deer (Odocoileus virginianus) in northeastern Minnesota (USA) were collected from 1984 through 1989 and tested for antibodies to six serovars of Leptospira interrogans (bratislava, canicola, grippotyphosa, hardjo, icterohemorrhagiae, and pomona) using a microtiter agglutination test. Eighty-eight (43%) sera were positive at greater than or equal to 1:100 for antibodies against serovars pomona and/or bratislava; none was positive for any of the other four serovars. None of the 31 sera collected in 1984-85 was positive, whereas all 54 sera collected from 1986 through 1988 had titers of greater than or equal to 1:100. During 1989, only 34 (29%) of 119 sera had titers of greater than or equal to 1:100. Based on these results, we believe there to be wide variability in exposure of Minnesota deer to Leptospira interrogans.

Agglutination Tests↗
PubMed1991

Cardiotonic drugs inhibit purified mammalian acetylcholinesterase.

Oxime- and non-oxime-related drugs, as well as cardiotonic drugs (CDs), have been used to treat the effects of organophosphorus (OP) poisoning. We conducted our experiments to determine what effects CDs may have on acetylcholinesterase (AChE), and how CDs interact with other treatment drugs as well as with OP-inhibited AChE. True AChE (EC 3.1.1.7) was purified from fetal bovine serum, and enzyme activity was measured according to Ellman et al. The CDs coumingine, cassaine, proscillaridin and convallatoxin were incubated with AChE at 550 microM at pH 7.6 and 25 degrees C. The CD ouabain was incubated with AChE at 500 microM. The CDs inhibited AChE by 97%, 89%, 10%, 7% and 6%, respectively. The mean AChE activities for these experiments, except for ouabain, were significantly different (P = 0.05) from their controls, as determined by the two-tailed Student's t-test. In a separate experiment, the oxime TMB-4.2Br (100 microM), which did not inhibit AChE, increased the inhibitory effect of proscillaridin from 4% to 11% (a 3.7-fold increase). When AChE was inhibited 39% with 37 nM VX, the addition of proscillaridin increased the inhibition to 51% (a 1.3-fold increase). When TMB-4 was added to the proscillaridin- and VX-inhibited AChE mixture, the inhibition decreased from 50% to 32% (a 0.37-fold decrease), whereas TMB-4 alone added to VX-inhibited AChE decreased the inhibition from 39% to 24% (a 0.38-fold decrease). The results show that TMB-4 increases the inhibition of AChE by proscillaridin. However, TMB-4 decreases the inhibition of AChE by VX and proscillaridin combined.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

A novel approach to the assessment of afferent pupillary defects.

The pupil response to a flashing light stimulus was observed for a group of 26 healthy volunteer controls, and 15 patients with relative afferent pupillary defects (RAPDs). For the control group, the mean interval between flashes which would just produce a perceptible pupil response was 295 milliseconds (ms). The mean difference between right and left eyes was 8.84 ms. The mean difference between normal and abnormal eyes of the APD group was 78.6 ms. The difference between these results and those of the control group are highly significant statistically (p less than 0.001), and we conclude that this test may be of use in the assessment of defects of the afferent light pathways.

Adult↗
PubMed1991

A 1-y walking program and increased dietary calcium in postmenopausal women: effects on bone.

The effects of a supervised 1-y walking program and increased dietary calcium (milk supplement, 831 mg/d, vs placebo drink, 41 mg/d) on bones were examined in 36 postmenopausal women (60.2 +/- 6.5 y). Trabecular bone-mineral density (BMD) of the lumbar spine (L1-L3), measured by computed tomography, increased by 0.5% in exercising women (n = 18) and decreased by 7.0% in sedentary women (n = 18; P = 0.02). Femoral-neck BMD measured by dual-photon absorptiometry (DPA) increased by 2.0% in women consuming high dietary calcium (n = 18) and decreased by 1.1% in those on moderate calcium intake (n = 18; P = 0.001). Neither exercise nor dietary calcium had an effect on lumbar spine (L2-L4) measured by DPA, distal radius measured by single-photon absorptiometry, or total body calcium measured by in vivo neutron activation. The varying proportions and rates of turnover of trabecular and cortical bone from one site to another suggest that exercise and high dietary calcium may preferentially alter bone density at different skeletal sites.

Absorptiometry, Photon↗
PubMed1990

Brain maps and parallel computers.

It is well known that neural responses in many brain regions are organized in characteristic spatial patterns referred to as brain maps. It is likely that these patterns in some way reflect aspects of the neural computations being performed, but to date there are no general guiding principles for relating the structure of a brain map to the properties of the associated computation. In the field of parallel computing, maps similar to brain maps arise when computations are distributed across the multiple processors of a parallel computer. In this case, the relationship between maps and computations is well understood and general principles for optimally mapping computations onto parallel computers have been developed. In this paper we discuss how these principles may help illuminate the relationship between maps and computations in the nervous system.

Brain↗
PubMed1990

Ketoconazole in the treatment of blepharitis.

A double masked, placebo controlled clinical trial, of topical 2% ketoconazole cream with lid hygiene, for the treatment of seborrhoeic and mixed seborrhoeic/staphylococcal blepharitis was conducted. Forty patients with symptomatic blepharitis, 20 randomly allocated to ketoconazole, 20 to placebo were entered. Treatment efficacy was assessed by improvement of symptoms using visual analogue scales, appearance of the eyelids and reduction in numbers of pityrosporum yeasts on the eyelids. Both groups showed a similar reduction in symptoms, and signs of inflammation. The overall clinical impression in the ketoconazole group was better at week five than in the placebo group. Sixty nine per cent were either normal or markedly improved, as compared to 42% in the placebo group, although this was not statistically significant (p less than 0.1, one-sided Mann-Whitney). Pityrosporum numbers were reduced significantly in both groups during the treatment period. Ketoconazole was no better than placebo at improving the symptoms of blepharitis. More ketoconazole treated patients had normal or markedly improved lids after treatment than the placebo group. Pityrosporum yeasts may play a role in blepharitis, and treatment with an antifungal has some advantages over conventional therapy.

Adult↗
PubMed1990

Cyclocryotherapy: a review of cases over a 10-year period.

There are conflicting reports on the value of cyclocryotherapy in the management of glaucoma. This retrospective study was carried out to assess the efficacy and complication rate of this procedure. The case notes of all patients undergoing cyclocryotherapy at a single centre over a 10-year period were reviewed. Case records were available for 68 eyes of 64 people. Thirty-eight eyes had neovascular glaucoma, nine had aphakic glaucoma, nine had angle closure glaucoma, three had primary open angle glaucoma, and nine had secondary open angle glaucoma. The mean follow-up periods for these groups varied from 2.0-6.3 years. The mean reduction in intraocular pressure following treatment varied from 7.9 mm Hg in the secondary open angle glaucoma group to 24.3 mm Hg in those with angle closure glaucoma. Pressure was controlled in 29.4% overall, ranging from 66.7% in the angle closure and primary open angle groups to 0% in the secondary open angle group. Of the painful eyes 71% were rendered comfortable, indicating that pain relief from cyclocryotherapy is not due solely to pressure control. 30% of the patients lost their vision following the procedure, phthisis occurred in 11.8% and four eyes (5.9%) went on to enucleation. Our results indicate that cyclocryotherapy affords good pain relief, without good pressure control, in various types of glaucoma. While there is an apparent high complication rate, visual loss and phthisis cannot be ascribed directly to the procedure, since these are eyes with a poor prognosis.

Adolescent↗
PubMed1990

Silastic foam dressing for healing exenteration cavities.

Dressing the exenterated orbital cavity is difficult and time consuming for staff, traumatic to the healing wound, and painful for the patient, particularly when the wound is being left to granulate. We report the use of a silastic foam dressing which offers a number of advantages in this clinical situation.

Bandages↗
PubMed1989

Recurrent multiple-branch retinal arteriolar occlusions in a patient with protein C deficiency.

A 34-year-old woman is presented who has recurrent, multiple, retinal arteriolar occlusions associated with a deficiency in protein C, a vitamin K-dependent anticoagulant. Protein C is a naturally occurring anticoagulant and if there is a deficiency, it can lead to episodes of thrombosis; the deficiency can be acquired or congenital. This is the first documented case of retinal arteriolar occlusion associated with a congenital deficiency of this protein. The mechanism for arteriolar occlusion in this patient is discussed, and whilst the role of protein C deficiency remains presumptive, it is strongly implicated.

Adult↗
PubMed1989

Keratoglobus in the Rubinstein-Taybi syndrome.

The case of a 20-year-old male with the Rubinstein-Taybi syndrome associated with unilateral acute corneal hydrops is presented. The initial findings were of keratoglobus, but after the corneal oedema had settled the cornea assumed a more conical contour. The relationship between keratoglobus, keratoconus, and acute hydrops is discussed.

Abnormalities, Multiple↗
PubMed1989

Effect of exercise and menstrual cycle status on plasma lipids, low density lipoprotein particle size, and apolipoproteins.

Habitual physical exercise has been reported to have beneficial effects on plasma lipoproteins. To examine this question in women, plasma cholesterol, triglyceride, and apolipoprotein (apo) A-I and B levels, and low density lipoprotein (LDL) particle size were determined in 25 women runners (9 of whom had exercise-related secondary amenorrhea) and 36 age-matched nonexercising women (controls). The eumenorrheic runners had significantly lower apo B levels and significantly greater mean apo A-I/apo B ratios and LDL particle sizes than did the control women (P less than 0.05). Lower apo B levels were correlated with decreased body mass index, a known exercise effect (P less than 0.0001). In addition, normally menstruating runners had cholesterol and triglyceride levels that were 7.6% and 25.4% lower, respectively, and apo A-I levels that were 6.4% higher than control women (P = NS). In amenorrheic runners all parameters were similar to values in control women, except that apo B levels were 20% lower (P less than 0.05). Amenorrheic runners had lower plasma apo A-I levels (13%) and significantly lower apo A-I/apo B ratios and estradiol levels than eumenorrheic runners, and serum estradiol values in the runners were correlated with apo A-I levels (P less than 0.01). These data indicate that the beneficial effects of strenuous exercise on plasma apo A-I levels and apo A-I/apo B ratios in women runners can be reversed by exercise-induced amenorrhea and decreased serum estradiol levels, and that women runners have lower apo B levels than nonexercising women, regardless of menstrual status.

Adult↗
PubMed1988

Hormone and bone mineral status in endurance-trained and sedentary postmenopausal women.

Serum hormone levels and bone mineral status were studied in 18 sedentary and 15 endurance-trained postmenopausal women (mean age, 62 yr). The endurance-trained women had lower body weight, lower body fat, and higher aerobic capacity than the sedentary women (P less than 0.05). There were no differences in current calcium intake between the 2 groups, as assessed by a 7-day food record, but carbohydrate intake (grams per kg BW) was higher in the endurance-trained women (P less than 0.001). Bone mineral density (BMD) of the spine (L1-L3), proximal femur, and radius did not differ between the 2 groups; however, when normalized for body weight, the BMDs of the spine and radius were higher in the endurance-trained than in the sedentary women. Serum estrone and PTH levels were lower, and 1,25-dihydroxyvitamin D and somatomedin-C levels were higher in the endurance-trained than in the sedentary women. Serum GH tended to be higher in the endurance-trained than in the sedentary women (P = 0.08), and there was a postexercise increase in serum GH in the endurance-trained, but not in the sedentary, women (P less than 0.01). The major effect of habitual exercise was on body weight and hormone status. Although leanness and low serum estrone levels are risk factors for osteoporosis, these were not associated with lower BMD in endurance-trained women. Endurance-trained women may have improved calcium absorption as a result of higher carbohydrate intake and higher serum 1,25-dihydroxyvitamin D levels.

Adult↗
PubMed1987

Counteracting the effects of mydriatics. Does it benefit the patient?

The effect of 2% pilocarpine nitrate in countering mydriasis, cycloplegia, and change in visual acuity due to 0.5% tropicamide was studied in 23 healthy volunteers. There was no significant difference in the decrease in pupil size or the rate of return of accommodation between the eye that received pilocarpine and the control eye. The effect of tropicamide on visual acuity was slight. In four (17%) of 23 eyes that received pilocarpine, visual acuity was reduced to 6/36 or worse. It is suggested that the use of 2% pilocarpine in the attempted reversal of 0.5% tropicamide to improve a patient's vision is not helpful and may possibly be harmful.

Accommodation, Ocular↗