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Biomedical subjects

T Thacher

Publications and source records attributed to T Thacher.

9 recordsLinked to original sources
PubMed2006

Sexual problems among married Nigerian women.

We interviewed and examined 293 married women, 15-49 years of age, seeking primary care at a teaching hospital in central Nigeria. One or more sexual problems were identified in 71% of women. The proportion of specific sexual problems was 39% for a desire problem, 40% for an arousal problem, 31% for a sex pain problem and 55% for an orgasmic problem. Poor marital communication, lack of foreplay, Islamic religion and advancing age were independently associated with a desire problem. Absence of foreplay was independently associated with an arousal problem. Lack of foreplay, lower abdominal pain, gynaecological conditions, working outside the home and younger age were independently associated with a sex pain problem. The absence of foreplay, poor marital communication and being a housewife were independently associated with an orgasmic problem. Sexual problems are common among married Nigerian women seeking outpatient care.

Adolescent↗
PubMed1999

Rickets in Nigerian children: response to calcium supplementation.

In a previous study of rachitic children in Jos, Nigeria we concluded that inadequate dietary intake of calcium was the primary contributing factor to the development of their rickets. The objective of the present study was to determine the effect of calcium supplementation in 10 children with radiographically and biochemically proven rickets from the same geographical area. Rachitic children were provided with calcium supplements of 1000 mg/day for a period of 3 months. Serum and urine samples were obtained at baseline and at 24 hours, 1 week, 4 weeks, and 12 weeks after initiation of supplementation. Serum calcium, phosphorus, alkaline phosphatase, intact parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were measured at each time point. Dietary recalls obtained at two separate times were used to estimate usual daily intakes of calcium and phosphorus. Ten non-rachitic age-matched controls from the same geographical area were recruited for comparison. Nine of 10 rachitic subjects had radiographic evidence of healing after 3 months of calcium therapy. Although serum calcium concentrations returned to control levels, other biochemical data indicated that the rickets of these subjects may have been multifactorial in aetiology, pointing to a possible defect in the synthesis of 25-hydroxyvitamin D.

Anthropometry↗
PubMed1999

Aminoaciduria in calcium-deficiency rickets in northern Nigeria.

Generalized aminoaciduria is associated with vitamin D-deficiency rickets in humans, but there is little information regarding aminoaciduria in rickets caused by primary calcium deficiency. In contrast to rickets in other parts of the world, this bone disease in Nigeria is caused primarily by inadequate intake of dietary calcium. We conducted a clinical trial in Jos, Nigeria in 10 children with radiographically and biochemically proven rickets; an equal number of non-rachitic healthy children from the same area served as controls. Serum and 24 h urine samples were obtained at baseline and at 24 h, 1 week, 4 weeks, and 12 weeks after initiation of calcium supplementation (1000 mg/day) and were analysed for their content of amino acids. Serum calcium, phosphorus, intact parathyroid hormone (PTH), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were also measured at each time point. In the rachitic subjects urinary amino acid concentrations were elevated from 2- to 16-fold at baseline, while serum amino acid levels increased 1.5- to 3.8-fold compared to controls. After 12 weeks of calcium supplementation, serum and urine amino acids decreased. There was no correlation between the degree of aminoaciduria and serum PTH or 1,25-dihydroxyvitamin D concentrations. We conclude that the aminoaciduria in these rachitic children was related to their calcium status and not to their vitamin D or PTH status.

Amino Acids↗
PubMed1998

Calcium supplements increase the serum levels of crosslinked N-telopeptides of bone collagen and parathyroid hormone in rachitic Nigerian children.

OBJECTIVES: Biochemical markers of bone turnover were measured in the sera of 16 controls and 10 children with calcium-deficiency rickets, during a 12-week course of calcium supplementation (1 g CaCO3/d) that was effective in healing the bone lesions of the rachitic children. DESIGN AND METHODS: Serum levels of crosslinked N-telopeptides of bone collagen (NTx), parathyroid hormone (PTH), alkaline phosphatase (ALP), and urinary deoxypyridinoline (LP) were assayed at baseline and during the course of calcium therapy and compared with data of the 16 non-rachitic controls. RESULTS: Calcium therapy suppressed serum NTx and PTH levels in the rachitic children within 24 h; however, after the first week, PTH and NTx levels increased to the extent that at 12 weeks both were elevated when compared with controls or to baseline levels. Serum levels of NTx and PTH were correlated in the controls and experimental subjects (r = 0.63, p < 0.001). CONCLUSIONS: The rate of bone resorption, as estimated by serum NTx concentration, is increased during the healing of rachitic lesions.

Alkaline Phosphatase↗
PubMed1995

Parametric sensitivity analysis of avian pancreatic polypeptide (APP).

Computer simulations utilizing a classical force field have been widely used to study biomolecular properties. It is important to identify the key force field parameters or structural groups controlling the molecular properties. In the present paper the sensitivity analysis method is applied to study how various partial charges and solvation parameters affect the equilibrium structure and free energy of avian pancreatic polypeptide (APP). The general shape of APP is characterized by its three principal moments of inertia. A molecular dynamics simulation of APP was carried out with the OPLS/Amber force field and a continuum model of solvation energy. The analysis pinpoints the parameters which have the largest (or smallest) impact on the protein equilibrium structure (i.e., the moments of inertia) or free energy. A display of the protein with its atoms colored according to their sensitivities illustrates the patterns of the interactions responsible for the protein stability. The results suggest that the electrostatic interactions play a more dominant role in protein stability than the part of the solvation effect modeled by the atomic solvation parameters.

Animals↗
PubMed1988

A hybrid approach to theoretical analysis of bovine pancreatic trypsin inhibitor.

A static analysis of bovine pancreatic trypsin inhibitor (BPTI) is presented based on a new discrete/continuum approach to modeling the dynamics of biomolecules. This hybrid method utilizes knowledge of the intramolecular potential and molecular configuration to generate a field of elastic modulus tensors. These tensors, which relate the local stress and strain for each atom in the biomolecule, can be used to judge the local rigidity as well as indicate regions of high stress. Comparing the tensor fields for an unrelaxed and a relaxed configuration, the microscopic structure of BPTI is found to be anisotropic and to have regions of stress even when it is relaxed in the potential field. However, when these fields are averaged over the whole protein or over individual residues the structure becomes more isotropic and the stressed regions vanish. Using these averaged tensors, we calculated bulk properties such as Young's modulus and the Lamé constants and they agreed with previously reported values.

Aprotinin↗
PubMed1980

Arginine-rich histones do not exchange between human and mouse chromosomes in hybrid cells.

Following division of HeLa-3T3 heterokaryons, human and mouse chromosomes occupy distinct regions within the resulting hybrid nuclei. This favorable orientation of genomes has allowed us to determine whether histones exchange between chromosomes in vivo. Acrylamide gel electrophoresis of the proteins from HeLa cells labeled with 3H-arginine during S phase showed that the core histones were labeled preferentially, constituting 30% of the total cellular tritium and 50% of the label in a crude nuclear fraction. Autoradiographic analysis of cells formed by fusion of 3H-arginine-labeled HeLa cells and 3T3-4E cells showed that 3H-arginine-labeled proteins did not migrate between nuclei in heterokaryons; hybrid cells formed from such heterokaryons contained nuclei in which 3H proteins occupied a sector within the nucleus; "sectored nuclei" could persist for at least 4 days; and the unequal distribution of 3H proteins did not change during DNA synthesis. Electron microscopic examination of hybrid nuclei failed to reveal a physical partition between human and mouse chromosome sets. Sectored nuclei were also observed in synkaryons derived from 3H-arginine-labeled HeLa and unlabeled HeLa cells, indicating that the unequal distribution of 3H-arginine-labeled proteins in HeLa-3T3 hybrid cells did not result from species-specific binding of proteins and DNA. The persistent unequal distribution of 3H-arginine-labeled proteins within hybrid nuclei in the apparent absence of a barrier between mouse and human chromosomes indicates that histones, the principal 3H-arginine-labeled proteins do not dissociate from DNA in vivo.

Animals↗
PubMed1979

Degradation of proteins microinjected into cultured mammalian cells.

Iodinated proteins were degraded after injection into HeLa cells at first-order rates with half-lives varying from three hours for the trout monhistone chromosomal protein, HMG-T, -to 60 hours for whale myoglobin. Fluoresceinated-bovine serum albumin (fl-BSA) was degraded almost twice as fast as unmodified BSA. The rate of degradation of 125I-BSA was very similar in eight cell lines of mouse, human, monkey and rat origin. Microinjected proteins were analyzed on SDS-acrylamide gels after injection, and for BSA and immunoglobin G, all remaining intracellular 125I migrated at the molecular weight of the injected proteins. By contrasting, more than 80% of the extracellular 125I chromatographed as iodotyrosine. With the exception of fl-BSA, which exhibited perinuclear accumulation in approximately one-half of the injected cells, autoradiography showed that throughout the period of study the injected proteins remained dispersed in the cytoplasm.

Animals↗