Search PubMed⌕ Search

Biomedical subjects

L M Nelson

Publications and source records attributed to L M Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1987

Replacing the acetyl linkage in aspirin with choline and magnesium moieties reduces the occurrence of gastric mucosal injury.

The acetyl moiety in aspirin (acetyl salicylic acid: ASA) is considered to play a major part in the pathogenesis of ASA-induced mucosal injury. At equivalent salicylate doses and pH values, the induction of acute gastric mucosal haemorrhagic erosions in rats by ASA and choline magnesium trisalicylate (CMT), a new non-acetylated salicylate, with and without the potentiating damaging effect of taurodeoxycholic acid (TDCA) were compared. Test solutions were administered by per oral intubation to five groups of fasting Sprague-Dawley rats (n = 24). Gastric mucosa were examined after 4 hours and mucosal injury assessed by a lesion-scoring system. The incidence and severity (median lesion scores with quartiles) of the lesions were 83% and 13 (7:20) respectively for ASA (128 mg kg-1) compared with 17% and 0 (0:0) for CMT (128 mg kg-1) (P less than 0.001 and P less than 0.001). TDCA increased mucosal damage to 100% and 29 (20:34) for ASA compared with 30% and 0 (0:4) for CMT (P less than 0.001) and P less than 0.001). Serum salicylate levels (median values of 1.4 for ASA and 1.5 mmol litre-1 for CMT) were not significantly different. It is concluded that replacing the acetyl moiety in ASA with choline and magnesium moieties reduces the ASA-induced mucosal injury, without affecting blood salicylate concentrations.

Animals↗
PubMed1987

Neurology practice patterns in Colorado.

Eighty-one percent (47/58) of private-sector neurologists in Colorado responded to a mail survey of practice patterns. We evaluated patient load, degree of principal versus consultative care, and use of neurodiagnostic tests. Broad areas of neurologic education that were perceived to have been lacking during residency training were also addressed. Eight-four percent (41/49) of responding neurologists agreed to participate in a more comprehensive prospective study of neurology practice patterns. The prospective data will provide information to determine how many neurologists are needed and the applications for neurologic education.

Colorado↗
PubMed1986

Primary and secondary closure of ampullary salpingotomy compared in the rabbit.

Because there is disagreement as to how linear ampullary salpingotomy should heal, primarily or secondarily, we compared the two methods with the use of rabbit oviducts in which conditions simulating ectopic pregnancy had been induced. Pregnancy rates (86% versus 75%), nidation indices (62% versus 54%), and percentage of adhesion-free tubes (50% versus 32%) were greater after primary closure, but these differences were not statistically significant. Ampullary tuboperitoneal fistulae occurred at the site of operation in 6.8% of tubes and impaired fertility (P less than 0.005).

Animals↗
PubMed1986

The Relationship between H(2) Evolution and Acetylene Reduction in Pisum sativum-Rhizobium leguminosarum Symbioses Differing in Uptake Hydrogenase Activity.

Peas (Pisum sativum L.) were inoculated with strains of Rhizobium leguminosarum having different levels of uptake hydrogenase (Hup) activity and were grown in sterile Leonard jars under controlled conditions. Rates of H(2) evolution and acetylene reduction were determined for intact nodulated roots at intervals after the onset of darkness or after removal of the shoots. Hup activity was estimated using treatment plants or equivalent plants from the growth chamber, by measuring the uptake of H(2) or (3)H(2) in the presence of acetylene. In all cases, the rate of H(2) evolution was a continuous function of the rate of acetylene reduction. In symbioses with no demonstrable Hup activity, H(2) evolution increased in direct proportion to acetylene reduction and the slopes were similar with the Hup(-) strains NA502 and 128C79. Hup activity was similar in strains 128C30 and 128C52 but significantly lower in strain 128C54. With these strains, the slopes of the H(2) evolution versus acetylene reduction curves initially increased with acetylene reduction, but became constant and similar to those for the Hup(-) strains at high rates of acetylene reduction. On these parallel portions of the curves, the decreases in H(2) evolution by Hup(+) strains were similar in magnitude to their H(2)-saturated rates of Hup activity. The curvilinear relationship between H(2) evolution and acetylene reduction for a representative Hup(+) strain (128C52) was the same, regardless of the experimental conditions used to vary the nitrogenase activity.

Journal Article↗
PubMed1986

Higher than expected prevalence of multiple sclerosis in northern Colorado: dependence on methodologic issues.

A population-based study of multiple sclerosis (MS) was conducted in 2 northern Colorado counties in 1982 to determine MS prevalence, to compare the rates with recent North American surveys and to compare the methods used in these studies. Provisional cases were identified from: the patient rolls of MS service organizations, chart reviews in 2 neurology practices, a survey of physicians and a review of hospital discharge diagnoses. Crude-point prevalence for the 2-county region was 84 per 100,000. The age-adjusted rate was higher than the rate for the region above the 37th parallel projected from data in a 1976 national survey, but was comparable to rates obtained in localized surveys conducted in the northern tier of the country. The methodological results revealed that the highest yield sources were the MS service organizations and the neurology practice chart reviews. MS prevalence surveys which neglect these methods may underestimate MS prevalence by as much as 20-40%.

Adult↗
PubMed1986

The effects of pregnancy in multiple sclerosis: a retrospective study.

We reviewed the medical records of 178 women with multiple sclerosis to evaluate the number of completed pregnancies, current disability status, and relationship of pregnancy to onset of MS symptoms. We found no differences in the long-term disability of women with no pregnancies, one pregnancy, or two or more pregnancies. Women who had initial symptom onset in pregnancy experienced less subsequent disability than women whose symptoms began before or after pregnancy. Therefore, pregnancy per se or number of pregnancies has no effect on subsequent disability.

Adult↗
PubMed1985

Functional and structural changes of the human proximal small intestine after cytotoxic therapy.

The effects of cytotoxic therapy on the structure and function of the proximal jejunum were studied in six patients receiving intravenous cyclophosphamide (300 mg/m2), methotrexate (40 mg/m2), and 5-fluorouracil (600 mg/m2) as adjuvant therapy for breast cancer. Using a steady state, triple lumen tube perfusion system the absorption of water and electrolytes was measured before and 48 h after administration of the cytotoxic agents. Jejunal biopsies were obtained at each perfusion. Median (range) water absorption fell from 126 (40-142) to 84 (46-142) ml/h/30 cm, with parallel changes for electrolytes; none of the changes was significant. Brush border disaccharidases did not change at 48 h after chemotherapy, while mature enterocytes appeared normal by both light and electron microscopy. Crypt cells and immature enterocytes, however, showed focal vacuolation by light microscopy, corresponding to the occurrence of large residual bodies (secondary lysosomes) containing partially degraded fragments of damaged crypt cells. The confinement of ultrastructural changes to the immature cell population may explain the failure of this study to show a consistent change in the absorptive function of the jejunum 48 h after chemotherapy.

Adult↗
PubMed1984

Conventional and simplified microsurgical isthmic tubal anastomosis compared in the rabbit.

Because the fallopian tube has potential for spontaneous recanalization, a simplified technique for isthmic anastomosis has been previously proposed. This study compares the simplified technique, which uses only one suture to approximate the tube, with a conventional isthmic anastomosis. The nidation index and patency rate subsequent to these procedures on the rabbit oviduct were evaluated. The conventional anastomosis gave a significantly better nidation index (P less than 0.01) and a patency rate (P less than 0.05). Even when tubal patency was established with the simplified technique, the nidation index may have been less than with conventional anastomosis (P less than 0.07). Gynecologic microsurgeons should continue to strive for the best anatomic repair possible when performing isthmic anastomosis and not rely on the fallopian tube's potential for spontaneous recanalization.

Animals↗
PubMed1984

Studies on the protective effect of deglycyrrhinised liquorice against aspirin (ASA) and ASA plus bile acid-induced gastric mucosal damage, and ASA absorption in rats.

By per-oral intubation of the stomach, four groups of rats (n = 22) received ASA 64 mg/kg, alone or with taurodeoxycholic acid (TDC, 5 mM), DGL (2000 mg/kg) or TDC plus DGL. At four hours the severity of bleeding was assessed by a lesion scoring system and expressed as medians and quartiles. In a separate study two groups of rats (n = 7) received ASA (128 mg/kg) or ASA plus DGL (2000 mg/kg) and salicylate levels measured in serial tail blood samples at 20, 40, 60 and 80 minutes. Lesion scores were increased from 6(3;10) with ASA alone to 12(5;16) by TDC (p less than 0.05) and reduced by DGL to 1(0;3.5) for ASA alone and 3.5(0;6) for ASA plus TDC (p less than 0.0005 in both cases). In the second study a slight reduction of ASA absorption was found only at 20 minutes with a median level of 0.9 mmol/l for the DGL treated rats and 1.2 mmol/l for the ASA alone group (p less than 0.05). No differences were found at the other times. We have also demonstrated that although DGL diminished ASA (128 mg/kg)-induced gastric mucosal damage from 17(12;25) to 8(3;14) (p less than 0.005) when the two were given together it did not do so significantly when DGL was given before ASA--15(20;22). Intraperitoneal DGL reduced lesion scores from ASA (128 mg/kg) from 14(11;24) to 7(1;19) (p less than 0.03), thus indicating a systemic as well as a local effect of the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Evoked potential abnormalities in myotonic dystrophy.

Past investigators have reported evidence of central nervous system involvement in myotonic dystrophy (MYD), including EEG abnormalities, ventricular enlargement, thalamic inclusion bodies, and impaired tests of cognitive function. Brain stem auditory evoked potentials have not been reported in myotonic dystrophy. We report the results of brain stem auditory (BAEP) and median nerve somatosensory (MSSEP) evoked potentials in 15 patients with MYD (9 males, 6 females, mean age = 35.8 +/- 11.4 years). BAEPs were abnormal in 53.3% (P less than 0.05). Four patients had abnormal wave I-III interwave latencies, 3 had abnormal wave III-V latencies, and 1 patient had both wave I-III and wave III-V latencies prolonged. MSSEPs were abnormal in 13.3% (P N.S.). Both patients showed a delay of the P15-N19 thalamic complex. Both patients had a normal clinical sensory examination and normal peripheral nerve conduction. No correlation was found between abnormal evoked potentials and patient age. A sex difference, however, was noted with 8/9 males having one or more abnormal evoked potentials compared with 0/6 females. Though our finding of abnormal MSSEPs was not statistically significant, both patients showed delay at the thalamic level, where pathology has been described. Abnormal ocular pursuit and sluggish pupillary reaction have implicated brain stem involvement in MYD. The abnormal BAEPs at the level of the pons and midbrain in this study provide neurophysiological evidence of brain stem pathology in MYD.

Adult↗
PubMed1983

A study of zinc metabolism in alcoholic cirrhosis.

1. Zinc metabolism was studied in 11 patients with alcoholic cirrhosis and 13 healthy volunteers using the isotope tracer 65Zn. 2. Intestinal absorption, whole-body content and total daily elimination of zinc were all increased in alcoholic cirrhosis, but the biological half-life of zinc did not differ from controls. 3. Hepatic zinc concentration was reduced in alcoholic cirrhosis and correlated with changes in hepatic alcohol dehydrogenase activity. 4. Patients with alcoholic cirrhosis in this study were not demonstrated to be zinc-deficient.

Adult↗
PubMed1983

Hydrogen Recycling by Rhizobium leguminosarum Isolates and Growth and Nitrogen Contents of Pea Plants (Pisum sativum L.).

The ability to recycle H(2) evolved by nitrogenase is thought to be of importance in increasing the efficiency of N(2) fixation and to be a factor in increasing plant yield in symbiotic systems. To determine whether this ability is a significant factor in the Rhizobium leguminosarum-Pisum sativum L. system, plants were inoculated with R. leguminosarum isolates which differed in their ability to oxidize H(2) and in their relative efficiency of N(2) fixation. These plants were grown at three levels of irradiance and harvested after 3, 4, and 5 weeks of growth for determination of C(2)H(2) reduction, H(2) evolution and uptake, plant dry weight, and N content. Plants inoculated with uptake hydrogenase-positive (Hup) isolates did not exhibit higher dry weight or N content than those inoculated with Hup isolates under any of the growth conditions studied. The efficiency of the nitrogenase system of Hup isolates increased at a low irradiance, a factor which may allow them to compete successfully with Hup isolates. In some HupR. leguminosarum isolates, H(2) oxidation is coupled to ATP formation, whereas in others, it is not. There were no differences in plant dry weight and N content in plants inoculated with the two types and grown for 5 weeks at three irradiance levels. The addition of H(2) to Hup nodules whose supply of photosynthate had been removed by stem excision did not increase C(2)H(2) reduction in either coupled or uncoupled types.

Journal Article↗
PubMed1983

Vitamin A deficiency in Crohn's disease.

Fifty two patients with Crohn's disease (31 outpatients and 21 inpatients) were investigated for evidence of vitamin A deficiency. Eleven (21%) had low plasma retinol concentrations (less than 1.2 mumol/l (34.3 micrograms %)). Five of these were outpatients and plasma retinol was only slightly reduced (greater than 1.0 mumol/l (28.6%)). All outpatients weighed 80% or more of ideal, and were considered at low risk of developing vitamin A deficiency. In contrast, of the six inpatients with low plasma retinol concentration, five had a level of less than 1.0 mumol/l (28.6 micrograms %) and weighed less than 80% ideal. Three of these had impaired dark adaptation and a plasma retinol concentration of less than 0.8 mumol/l (less than 22.9 micrograms %). As a group, the inpatients were more protein depleted than the outpatients, with respect to serum albumin (p less than 0.01), transferrin (p less than 0.001), and prealbumin (p less than 0.001) but retinol binding protein levels were not significantly lower. It is suggested that patients with extensive small bowel Crohn's disease, who weigh less than 80% of ideal weight, merit measurement of plasma retinol concentration. Those with plasma retinol less than 0.8 mumol/l (less than 22.9 micrograms %) run a high risk of night blindness. Vitamin supplements should be given and protein depletion corrected.

Adolescent↗
PubMed1982

Uptake hydrogenase activity and ATP formation in Rhizobium leguminosarum bacteroids.

The role of uptake hydrogenase was studied in Rhizobium leguminosarum bacteroids from the nodules of Pisum sativum L. cv. Homesteader. Uptake hydrogenase activity, measured by the 3H2 uptake method, was dependent on O-consumption and was similar to H2 uptake measured by gas chromatography. Km for O2 of 0.0007 atm (0.0709 kPa) and a Km for H2 of 0.0074 atm (0.7498, kPa) were determined. H2 increased the rate of endogenous respiration by isolates with uptake hydrogenase (Hup+) but had no effect on an isolate lacking uptake hydrogenase (Hup-). A survey of 14 Hup+ isolates indicated a wide range of H2 uptake activities. Four of the isolates tested had activities similar to or higher than those found in two Hup+ Rhizobium japonicum strains. H2 uptake was strongly coupled to ATP formation in only 5 of the 14 isolates. H2 increased the optimal O2 level of C2H2 reduction by 0.01 atm and permitted enhanced C2H2 reduction at O2 levels above the optimum in both a coupled and an uncoupled isolate. At suboptimal O2 concentrations a small enhancement of C2H2 reduction by H2 was seen in two out of three isolates in which H2 oxidation was coupled to ATP formation. Thus, the main function of uptake hydrogenase in R. leguminosarum appears to be in the protection of nitrogenase from O2 damage.

Adenosine Triphosphate↗