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Biomedical subjects

N Anderson

Publications and source records attributed to N Anderson.

At least 163 records · Page 9Linked to original sources
PubMed1985

Splenic abscess.

Abscess of the spleen is a rare entity. It may develop after generalized infection, hematologic disorders and trauma. The authors report the case of a 7-year-old boy who presented with a 2-month history of spiking fever, anorexia, fatigue and weight loss. He had left subcostal tenderness and a palpable spleen. He had a history of trauma to the left flank 5 months before admission but a splenic scan obtained at that time appeared normal. A splenic abscess was diagnosed by gallium scanning, computerized tomography and ultrasonography. Although splenectomy has been advocated as the treatment of choice for splenic abscess, this patient was treated successfully with appropriate antibiotics and simple drainage, preserving the spleen. Cultures grew Staphylococcus aureus. Of all the diagnostic methods available, ultrasonography is the least invasive study that will make the diagnosis and is less expensive than some methods.

Abscess↗
PubMed1983

X-ray pelvimetry: helpful or harmful?

This study was performed (1) to clarify the usefulness of x-ray pelvimetry in diagnosing cephalopelvic disproportion (CPD), particularly in patients with abnormal labor, and (2) to examine the association between infant birthweight and mode of delivery. The subjects were 100 consecutive patients who underwent x-ray pelvimetry. A retrospective chart review was done to collect demographic data and evaluate Friedman labor curves. Radiologic dimensions were tabulated for anteroposterior diameter, transverse diameter, and summation plane values of both inlet and midpelvic planes. Average pelvimetric values for subjects delivered vaginally and those delivered abdominally were compared, and Hotelling's T2 analyses were conducted to determine whether the differences were statistically significant. Average birthweights of infants born to women in cesarean section and vaginal delivery groups were also compared, with t tests conducted to determine statistical significance. Results showed that even in a select group of patients in abnormal labor with the highest probability of CPD--a condition it was believed x-ray pelvimetry could diagnose--no significant difference in bony pelvic dimensions existed between vaginal and cesarean delivered patients. The cesarean group did, however, deliver significantly heavier infants. The results question the usefulness of x-ray pelvimetry in diagnosing CPD.

Birth Weight↗
PubMed1982

Serial depletion and regeneration of the murine hematopoietic system. Implications for hematopoietic organization and the study of cellular aging.

The mouse hematopoietic system was subjected to repeated depletion and regeneration either by serial transfer of bone marrow cells through lethally irradiated recipients or by repeated treatment with the cycle-active drug hydroxyurea (HU). The capacity of surviving stem cells to proliferate and self-renew was assayed at intervals by two methods: (a) the spleen colony method; and (b) competitive repopulation of irradiated recipients using chromosome markers, with normal bone marrow cells as an internal control. The progressive decline in stem cell function that occurred during serial transfer of bone marrow and that had already begun after a single transfer was not seen during HU treatment; up to 25 pairs of HU injections given over more than 1 yr had no discernible effect on the number of stem cells present 3 wk after the final injection or on their capacity to self-renew. Within 2 d after exposure to HU, the average self-renewal capacity of surviving stem cells was enhanced. This implies that the drug selectively eliminates poorly self-renewing stem cells and hence that these enter cycle more readily than stem cells with a high self-replicative potential. However, the fact of being in cycle at the time of injection did not of itself affect self-renewal. The results show that serial transfer of bone marrow is not a valid method for studying clonal aging phenomena because it does not fulfill the assumptions on which such studies are based. No evidence was obtained for any intrinsic limitation in the capacity of bone marrow populations for repeated regeneration after HU-induced depletion. However, this does not necessarily imply that individual hematopoietic clones are capable of indefinite expansion because hematopoiesis may (as suggested by the relative resistance of highly self-replicative stem cells to mitogenic signals) proceed on the basis of clonal succession.

Animals↗
PubMed1982

Effects of a preventive and suppressive control scheme on the development of thiabendazole-resistance in Ostertagia spp.

Three years after the start of an experiment to assess the merits of thiabendazole (TBZ) treatment of trichostrongylid parasites in weaner sheep, field isolates of Ostertagia spp and Trichostrongylus spp were made from weaner sheep treated under one of three treatment schemes. Treatment frequencies were "nil", "planned" (5 or 6/year) and "regular" (every 3 weeks). In addition an isolate was taken from a group of "tracer" sheep drenched with TBZ every 10 days. Resistance to TBZ was assessed using an in vitro egg hatch assay, pre- and post-treatment faecal egg counts and a controlled anthelmintic efficiency test. Pre- and post-treatment egg counts revealed the presence of TBZ-resistance in field isolates of mixed species. Egg hatch assays indicated a level of resistance for Ostertagia spp which was proportional to the frequency of TBZ treatment. The "planned", "regular" and "tracer" strains of Ostertagia spp had resistance ratios for eggs of 4, 13 and 15 respectively when compared to the "nil" strain. In the anthelmintic efficiency assay treatment with 44 mg kg-1 and 88 mg kg-1 of TBZ removed 82 and 96% respectively of the total Ostertagia burden (adults and larvae) from the "nil" strain and 30 and 75% respectively from the "planned" strain. The same dose rates against the "regular" and "tracer" strains and additional rates of 132 or 176 mg kg-1 against the "tracer" strain failed to reduce the Ostertagia burden significantly. Intestinal Trichostrongylus spp from all isolates were fully susceptible to TBZ at 44 mg kg-1. Levamisole at 7.0 mg kg-1 was highly effective (99% reduction) against the "tracer" strain of Ostertagia.

Animals↗
PubMed1981

Antithrombin III profiles in malignancy, relationship primary tumors and metastatic sites.

Variations of antithrombin III were studied in a non-randomized population of consecutive cancer cases admitted to a referral hospital. Differences between functional and immunologic assay were observed. Decreases were observed in both assays when compared to a population of hospitalized controls. Patients with cancer of the colon, ovary and prostate showed a deficiency of antithrombin III more frequently than other common tumors. When all tumor cases were subdivided into those in remission compared to those with metastases, a significant decrease in antithrombin III also could be shown. Metastases to the liver were strikingly common in cancer patients with decreased antithrombin III. In these patients, the decrease in antithrombin III could be statistically correlated with reduction in serum albumin.

Antithrombin III↗
PubMed1981

Effects of Ostertagia circumcincta infections on plasma gastrin in sheep.

Radio-immunoassay of plasma gastrin showed that hypergastrinaemia developed in sheep during experimental infections with Ostertagia circumcincta. Elevations of plasma gastrin occurred within 8 days of the first dose of infective larvae, with the most marked increase being after 11-20 days when adult worms would be expected to be present in the abomasum. Increases of plasma gastrin levels from 69.0 +/- 7.6, 28.7 +/- 5.3, 48.7 +/- 5.9 and 60.6 +/- 9.4 pg/ml before infection to maxima of 650, 230, 900 and 750 pg/ml respectively were recorded in 4 sheep infected for the first time. In 2 others which had been previously infected and then treated with anthelmintic, plasma gastrin rose from 16.0 +/- 4.0 and 377 +/- 87 pg/ml to maxima of 260 and 900 pg/ml at 24 and 29 days after re-infection, respectively. The cause of hypergastrinaemia has not been established. The elevation of abomasal pH which occurs in ostertagiasis may result in increased gastrin levels but is thought not to be the only cause since plasma gastrin increased before the abomasal pH rose and developed in sheep infected for a second time although their abomasal contents remained at pH 4.0 or lower. The presence of the parasite is critical for development of hypergastrinaemia as shown by return of the gastrin level to normal following therapy with an anthelmintic. It was shown that the parasites do not depend on the hypergastrinaemia since O. circumcincta became established in antrectomized sheep in which hypergastrinaemia did not develop.

Animals↗
PubMed1980

Pancreatic alpha cell tumors: case report and review of the literature.

Twenty-eight cases of alpha cell tumors of the pancreatic islets have been reported. The clinical features include typical skin rash (termed migratory necrolytic erythema) and stomatitis with anemia, abnormal glucose tolerance, and weight loss. The time course of the disease is variable but the clinical syndrome may be present for up to 15 years (median five years) before discovery of the tumor. In 3 patients, cure was achieved by surgical resection, and in 17 patients in whom metastatic sites were evaluable, 16 involved the liver. Six patients have received chemotherapy: 4 with streptozotocin (STZ); 1 with dimethyl triazeno imidazole carboxamide (DTIC); and 2 with 5-fluorouracil. All 4 patients receiving STZ responded to therapy with objective regression of the tumor and in 3 the dermatitis syndrome receded as well. The selectivity of the STZ for beta cells observed in animals is contrasted with the specific antitumor activity of STZ for alpha as well as beta and delta cell tumors in man.

Adenoma, Islet Cell↗
PubMed1980

The effect of temperature on times to hatching of eggs of the nematode Ostertagia circumcincta.

A delayed gamma distribution satisfactorily described the distribution of times to hatching of Ostertagia circumcincta eggs incubated in 0.1% saline at temperatures between 6 and 20 degrees C. Below 6 degree C hatching of eggs was extremely variable. The relationship between rates of development and temperature within the range 10 to 20 degrees C was more closely described by a non-linear function than a linear one. The non-linear function was incorporated into a temperature summation equation which satisfactorily predicted the hatching of eggs incubated under conditions of alternating temperatures.

Animals↗
PubMed1980

Photoperiodic control of thyroid function and wool and horn growth in rams and the effect of cranial sympathectomy.

Eight adult Soay rams (four control and four superior cervical ganglionectomized) were housed in an artificial lighting regimen of alternating 16-week periods of long days [16 h of light, 8 h of darkness (16 L:8D)] and short days (8L:16D) for nearly 3 yr, and the long term variations in growth of the wool and horns were recorded along with measurements of the plasma concentration of T4, T3, and testosterone. In the control rams all of the parameters varied in relation to the imposed lighting regimen. An increase in the growth of the wool and horns occurred during each period of long days at a time when the circulating concentrations of T4 and T3 were high; at this time the animals were reproductively quiescent, with low plasma levels of testosterone. During each period of short days the rate of wool and horn growth declined, as did the plasma concentrations of T4 and T3, while the rams became sexually active with high plasma levels of testosterone. Moulting of the old coat occurred during the periods of long days, coinciding with the phase of increasing wool growth. The variations in the ganglionectomized rams were quite different from those in the controls, bearing no clear relationship to the imposed lighting regimen. In these operated animals there were long term changes in all of the parameters, but these were generally less pronounced than those in the controls. The unusual pattern in the growth of horns and wool was correlated with long term changes in the plasma levels of T4, T3, and testosterone. Moulting of the old coat did not occur in the normal manner in the animals after the first year.

Animals↗
PubMed1980

Controlled release of anthelmintic drugs: a new concept for prevention of helminthosis in sheep.

Anthelmintic effects of oxfendazole continuously released at 0:17, 0.28 and 0.47 mg/kg/day from intraruminal capsules were assessed in groups of sheep artificially infected with Ostertagia circumcincta. Removal of worms was directly related to both release rate and plasma concentrations of drug. At the highest level, worm burdens were removed within seven days of administration and anthelmintic efficiency was 99.9 +/- 0.04, 99.3 +/- 0.5 and 98.9 +/- 0.7 per cent against adult worms, developing fourth stage and early fourth stage larvae respectively. In a field experiment, comparisons were made of the parasitological and animal production differences between groups of weaned lambs which were given no treatment, a single oral dose of 5 mg/kg oxfendazole and capsules releasing either 0.24 or 0.48 mg/kg oxfendazole daily. By four days after administration of capsules worm egg counts were reduced and remained below detectable levels for up to 86 days. Worm counts from 'tracer' and flock sheep showed a reduction in worm numbers, especially for Trichostrongylus spp. Compared with untreated controls, live weight gain and fleece weight of sheep given capsules releasing 0.48 mg/kg oxfendazole daily was increased.

Animals↗
PubMed1979

Mesenchymal tumors associated with hypoglycemia: case report and review of the literature.

Hypoglycemia secondary to malignant tumors is rare. Mesenchymal tumors of nonpancreatic origin are the most common tumors associated with the hypoglycemia syndrome, and the clinical features of 115 reported cases are reviewed. The major anatomic distributions of the tumors are thoracic (30%) abdominal (65%), and uncommon locations (less than 5%). Approximately 50% of the tumors were resectable (59 patients), and in 60% the surgical procedure was curative. In the remaining 40% local recurrence predominated related to site of tumor and presence of contiguous organ invasion. The application of multimodality adjuvant therapy for hypoglycemia associated mesenchymal tumors should be based on an understanding of the natural history of the tumor.

Abdominal Neoplasms↗