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Biomedical subjects

A Taylor

Publications and source records attributed to A Taylor.

At least 415 records · Page 23Linked to original sources
PubMed1994

Dose-response characteristics of galactose-induced cataract in the rat.

The onset and progression of cataract was investigated in weanling Sprague-Dawley rats fed 10, 15, 20 and 30% dietary galactose (groups 1-4) for 45-226 days. Cataracts were graded on a 0-5 scale. After 226 days, 9% of the rats fed 10% galactose developed lesions beyond the very early stage of cataractogenesis (grade 1). After 154 days 50% of the rats fed 15% galactose developed subcortical cataract (grade 3) with no nuclear cataract. In the rats fed 20% galactose, an initial rapid development by 31 days of a grade 3 cataract was observed in 50% of the eyes. Advancement to grade 4 and grade 5 cataract proceeded more slowly; by 207 days, 45% of the eyes had grade 5 cataract. In rats fed 30% galactose, rapid vacuolization and development of nuclear cataracts (grade 5) were observed by day 44. Dietary galactose at levels of 20 and 30% was associated with a significant reduction in weight gain at the early stage of dietary treatment. These observations demonstrate that 10-30% dietary galactose induces cataract in rat lens in a dose- and time-dependent fashion. These data serve to further establish this animal model as a useful model for studying the sequelae of cataractogenesis.

Animals↗
PubMed1994

Renal artery stenosis and ischemia. Effect on renal blood flow and extraction fraction.

The clearance of [131I]orthoiodohippurate and 99mTc-mercaptoacetyltriglycine provide a measure of effective renal plasma flow, yet these clearances are proportional to renal plasma flow only if the extraction fraction remains constant. To determine the effect of unilateral renal artery stenosis, captopril, renal ischemia, and partial renal vein occlusion on renal blood flow and the extraction fraction of [131I]orthoiodohippurate, 99mTc-mercaptoacetyltriglycine, and [125I]iothalamate, we conducted a series of constant infusion studies in Sprague-Dawley rats. Renal artery flow reduction of approximately 70% decreased the extraction fraction of all three agents (P < or = .05). Captopril had no effect on extraction fraction in controls, but it produced a further decrease in extraction fraction of 99mTc-mercaptoacetyltriglycine and [131I]orthoiodohippurate in rats with renal artery stenosis (P < or = .05). Ischemia resulted in a 16% decrease in flow (P < .01) but a much larger (47% to 65%) decrease in extraction fraction of all three agents (P < .002). Partial renal vein occlusion also decreased the extraction fraction of all three agents (P < or = .05). The changes in extraction fraction imply that the clearances of [131I]orthoiodohippurate and 99mTc-mercaptoacetyltriglycine in disease states may not be proportional to renal plasma flow. Furthermore, in rats with renal artery stenosis it appears that renal blood flow must fall below a critical threshold of approximately 58% before extraction fraction decreases; as renal blood flow is further reduced below this threshold, there is a corresponding reduction in extraction fraction (P < .01).

Animals↗
PubMed1994

A characterization of the blood lead concentrations in Saudi Arabian children.

The results presented in this paper are those derived from an extensive analysis of lead in 1047 children aged 2 months to 16 years attending as outpatients at a reference hospital, taking cases from all parts of the Kingdom of Saudi Arabia. Since the distribution of blood lead data in the sample suggested the existence of two mixed sub groups among the studied children, a non-linear mathematical model was used fit to the data. More than 20% of the children had blood lead concentrations above 0.608 mumol/L (12.59 micrograms/dL).

Adolescent↗
PubMed1994

Mild hypomania (the highs) can be a feature of the first postpartum week. Association with later depression.

About 10% of women show elation and associated features of hypomania in the first 5 days following childbirth. These symptoms can be detected using a self-rating scale (the 'Highs') based on SADS-L criteria. This phenomenon has been confirmed using the observer-rated Comprehensive Psychopathological Rating Scale, which also revealed a high degree of related irritability. Significantly more women scoring > or = 8 on the Highs scale at 3 days postpartum went on to manifest depression at 6 weeks than did subjects with no psychopathology in the early puerperium. It is suggested that the 'highs' followed by depression may be a mild and common form of bipolar disorder.

Adult↗
PubMed1994

The effects of recombinant human insulin-like growth factor-I (IGF-I) administration on the levels of IGF-I, IGF-II and IGF-binding proteins in adolescents with insulin-dependent diabetes mellitus.

Insulin-dependent diabetes mellitus (IDDM) during puberty is associated with a reduction in circulating concentrations of insulin-like growth factor-I (IGF-I) and low IGF bioactivity. Altered levels of the IGF-binding proteins (IGFBPs), including low IGFBP-3 and elevated IGFBP-1, have also been described. These abnormalities have been linked to poor growth and deteriorating blood glucose control. We have therefore examined the effects of recombinant human IGF-I (rhIGF-I) administration on the levels of IGF-I, IGF-II, IGFBP-1, IGFBP-3 and IGF bioactivity in a group of 9 late-pubertal adolescents with IDDM. This was a double-blind placebo controlled study with each individual admitted on two occasions when either rhIGF-I (40 micrograms/kg) or placebo was administered by subcutaneous injection in the thigh at 1800 h. Blood samples were then taken for the subsequent 22 h. The half-life of administered rhIGF-I (12.1-22.2 h) was similar to that previously described in normal subjects. There was a small increase in IGFBP-3 concentrations overnight following rhIGF-I administration when compared to placebo, whereas the levels of IGF-II decreased. Under strict euglycaemic conditions, the relationship between insulin and IGFBP-I did not appear to be affected by rhIGF-I administration although the levels of IGFBP-1 tended to be higher overnight. IGF bioactivity was low during the placebo study, and although within the normal adult range following administration of IGF-I, was still relatively low for adolescents in late puberty.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Degradation of native and oxidized beta- and gamma-crystallin using bovine lens epithelial cell and rabbit reticulocyte extracts.

In many types of cells, modified proteins are selectively and rapidly removed by various proteolytic systems. In eye lens, as in most cells, there appears to be a multiplicity of proteolytic pathways, including ubiquitin-dependent, ATP-dependent and ATP-independent pathways. Each of these appears to be involved in the degradation of alpha-crystallins. The objective of this study was to determine if oxidized beta- and gamma-crystallins would be selectively degraded and which proteolytic systems might be involved. beta- and gamma-crystallins were oxidized by exposure to 137Cs radiation under N2O. This system generates *OH primarily. Oxidation of beta- and gamma-crystallins was indicated by decreased protein sulfhydryl content and tryptophan fluorescence, as well as by increased levels of carbonyl and high molecular weight aggregates with increasing radiation dose. gamma-crystallin was more susceptible than beta-crystallin to oxidation based on loss of native crystallin, increase in aggregates and fragmentation products, and loss of tryptophan. Low molecular mass polymers (dimers) appear to be the precursors of high mass aggregates induced upon oxidation. At a specific level of oxidative insult interchain covalent bonds in addition to disulfides were more extensive in the polymers of gamma-crystallin as compared to beta-crystallin. Except for beta-crystallin irradiated with 1 krad, the degradation rate of crystallins using both reticulocyte and bovine lens epithelial cells (BLEC) proteolytic systems increased in proportion to the extent of oxidation. Proteolysis of oxidized gamma-crystallins increased 1775% and 900%, respectively, using reticulocytes and BLEC supernatants as the source of proteases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1994

Zinc, copper and magnesium status in insulin-dependent diabetes.

In 20 patients with insulin-dependent diabetes mellitus the concentration of zinc in serum was 56.53 +/- 2.36 micrograms/dl (mean +/- SD). This was significantly lower (p < 0.01) than the levels measured in matched controls. In the same patients the concentrations of serum copper and magnesium were 123.46 +/- 6.59 micrograms/dl and 17.38 +/- 0.52 mg/l respectively. These copper values were higher and the magnesium levels were lower than in the control subjects (p < 0.01). These changes may be associated with the development of insulin resistance and it is proposed that patients will improve if trace elements are given as part of the therapy.

Adolescent↗
PubMed1994

Quality assurance in the management of alcohol withdrawal in a general hospital.

We have shown previously that a standardized protocol is effective in the management of alcohol withdrawal in a general hospital. In this study a Quality Assurance (QA) approach was used to determine whether all patients at risk were detected and treated correctly in time. A total of 500 episodes were monitored, 82% of patients at risk were identified, and 89% of patients were seen within 24 h (median 4 h). The protocol was followed correctly in 86% of cases but was inappropriately applied in 7.2%. Medication was given in 242 cases, on 93% of occasions according to guidelines. In all, 11.8% of episodes became complicated by seizure, hallucinations or confusion and two patients had terminal respiratory failure which worsened after sedation. A standardized protocol for alcohol withdrawal can be used in a general hospital with high rates of detection of at risk patients, a high rate of compliance with treatment guidelines and a low rate of complications.

Adolescent↗
PubMed1994

Psychological and sexual changes after the cessation of breast-feeding.

OBJECTIVE: To characterize the effect of breast-feeding cessation on the mood and sexuality of women after the birth of their first child. METHODS: Women in good physical and psychological health, who had been breast-feeding for 6-23 months and had responded to a request for subjects in a parents' magazine, collected data daily for 2 months before and 2 months after weaning. They were asked to rate 14 measures of psychological, physical, and sexual variables at the same time each day on 3- or 5-point scales. RESULTS: Nineteen women completed the study. Five of these subjects became pregnant before weaning and ceased breast-feeding when pregnancy was confirmed; their last menstrual period was 6 weeks before weaning. The non-pregnant women weaned their babies just before or during menstruation. After weaning, the nonpregnant women reported a significant decrease in fatigue, improvement in mood, and an increase in sexual activity, sexual feelings, and frequency of coitus. Significant changes in fatigue and mood occurred during the second week after weaning; in fatigue, sexual activity, and sexual intercourse during the third week; and in the frequency of sexual intercourse in the fourth week. THe results were not caused by the subjects' expectations about breast-feeding and sexuality or perineal comfort. The women who conceived did not show these changes; a gradual increase in fatigue and decline in sexuality was observed. CONCLUSION: In women who are not pregnant, the cessation of breast-feeding is associated with an improvement in mood, fatigue, and sexuality.

Adult↗
PubMed1994

Use of bone scintigraphy to select patients with multiple myeloma for treatment with strontium-89.

Strontium-89 is an effective agent for palliation of pain due to bony metastases from breast and prostate carcinoma. As a functional analog of calcium, 89Sr is taken up by bone in areas of osteoblastic activity. Since patients with multiple myeloma frequently have osteolytic metastases, 89Sr might not be considered to be a therapeutic option. However, metastases which appear osteolytic by radiographs may demonstrate osteoblastic activity on bone scans. Consequently, the bone scan may be used to identify a subset of patients with osteolytic metastases who may benefit from 89Sr treatment. This report describes a patient with severe rib pain due to multiple myeloma whose chest radiograph showed multiple lucent lesions throughout the bones of the chest wall but whose bone scan showed marked osteoblastic activity. The patient was treated with 89Sr and received substantial pain relief. Bone scans may be useful in selecting myeloma patients or other cancer patients with osteolytic radiographic lesions who may benefit from 89Sr therapy.

Bone Neoplasms↗
PubMed1994

Evaluation of technetium-99m-triamide-mercaptide complexes designed to identify properties favoring renal tubular transport.

UNLABELLED: To aid in the design of an improved 99mTc-labeled renal agent, several new [99mTcO(MAG3)]2- analogs were synthesized to determine the effects of varying the position and chemical form of the terminal charged group on renal clearance. METHODS: Clearance, extraction efficiency and plasma protein binding were measured in six Sprague-Dawley rats per complex for ortho, meta and para isomers of [99mTcO(MAG2-ABA)]2-, with MAG2- = mercaptoacetylglycylglycyl- and ABA = aminobenzoate; [99mTcO(MAG2-pASA)]2-, with pASA = p-aminosalicylate; [99mTcO(MAG2-AMS]2-, with AMS = aminomethylsulfonate; and [99mTcO(MAG2-AMP]3-, with AMP = aminomethylphosphonate. For agents with relatively poor clearances, hepatobiliary excretion was evaluated by using a camera-based method. RESULTS: The clearances of the ortho, meta and para isomers of [99mTcO(MAG2-ABA)]2- were 17%, 20% and 59% of those of OIH, respectively. The clearances of [99mTcO(MAG2-pASA)]2-, [99mTcO(MAG2-AMS)]2- and [99mTcO(MAG2-AMP)]3- were 32%, 46% and 39% those of OIH, respectively. CONCLUSION: Optimal tubular transport appears to require a terminal anionic group; a planar carboxylate is preferred over nonplanar -SO3- or -PO3(2-) substituents, suggesting that the smaller size and/or planar shape of the carboxylate group are probably more important than the total charge or charge distribution. Optimal transport also appears to depend on the oxo-carboxylate conformation (syn or anti) and the oxo-carboxylate distance, although these relationships can be modulated by steric interactions. These structure-distribution relationships are important factors to consider in the future design of renal radiopharmaceuticals.

Animals↗