Search PubMed⌕ Search

Biomedical subjects

A M Holmes

Publications and source records attributed to A M Holmes.

At least 19 recordsLinked to original sources
PubMed1995

Patient preference for health status screening instruments.

The Dartmouth Primary Care Cooperative Information Project (COOP) charts and mini-Duke-UNC Health Profile (DUHP) instruments were developed to screen patients' health status in clinical settings. The purpose of this study is to determine patient preferences for use of these instruments in a family practice setting. A sample of 203 consecutive, consenting patients presenting to a university-based family practice clinic was administered both instruments. Patients then completed a questionnaire which asked which instrument was preferred and why. Overall, neither instrument was significantly preferred by patients. Patient perceived accuracy for the COOP was significantly positively related to age and negatively related to quality of life. Patient ease, rather than perceived accuracy, dominated the preference relationship, yet neither instrument was found to be easier to use by the elderly or those in poorer health. This study reveals that patients prefer instruments which are easier to use, but that neither the COOP nor the mini-DUHP was found to be significantly easier to use by all patients. However, the COOP was perceived to be more accurate for a subset of patients, the elderly with poor quality of life beyond the realm of health.

Age Factors↗
PubMed1995

Expected hospital costs of knee replacement for rural residents by location of service.

This article assesses the relative cost of providing a specific procedure, knee replacement (KR) surgery, to rural residents in rural community-based hospitals rather than in urban hospitals. Costs are predicted using regression analysis with readily available data from Health Care Financing Administration's Medicare Provider Analysis and Review. The specification incorporates the effect of referral patterns on volume and the subsequent impact on costs in the different settings. The predicted cost per case was found to be lower in rural rather than urban hospitals across all patient types. Findings indicate scale economies exist for KR surgery in both the urban and rural hospital settings. Results also suggest the total cost of a hospitalization associated with KR surgery in rural hospitals is more sensitive to changes in procedure volume than in urban hospitals, providing preliminary support for increased regionalization of KR surgery in rural hospitals. While long-term outcome measures associated with successful KR surgery (improved function, reduced pain, etc.,) are not available, mortality rates and perisurgical complication rates were not significantly different between rural patients who received KR surgery in rural hospitals and those who received KR surgery in urban hospitals. Among rural hospitals, however, complication rates were significantly correlated with procedure volume (complication rates were significantly lower in rural hospitals that performed more than nine KR surgeries a year). Our results suggest KR surgery can be delivered efficiently in rural community-based settings and support the case for regionalization of this procedure. Key words: rural hospital; hospital cost; economics of scale; regionalization.

Aged↗
PubMed1990

Renovascular disease and renal complications of angiotensin-converting enzyme inhibitor therapy.

Renal complications of angiotensin-converting enzyme (ACE) inhibitor therapy are widely recognized, but few authors have documented the incidence or spectrum of these conditions. In a retrospective study of 530 consecutive patients presenting to our unit as acute uraemic emergencies over a six-year period, 85 (16 per cent) had renovascular disease that was considered to be responsible for their loss of renal function. Twenty-one (4 per cent) patients had uraemia which could be clearly attributable to ACE inhibitor treatment; 18 of these cases were shown to have significant renovascular pathology. Following withdrawal of the ACE inhibitor the renal failure reversed in the majority of patients. We also examined 400 consecutive hypertensive patients referred over a similar period and, although vascular imaging was performed only when it was considered to be clinically indicated, 58 (14.5 per cent) of these patients were shown to have renovascular pathology. A further five patients with stable chronic renal disease were seen to have a deterioration in their glomerular filtration rate coincident with commencement of ACE inhibitor therapy; this reversed when the agents were withdrawn. These observations indicate that significant renovascular disease may be more common than has been hitherto recognized and that injudicious use of ACE inhibitors may result in serious complications. Methods which may minimize such iatrogenic disease are suggested.

Acute Disease↗
PubMed1988

Calcium-dependent calmodulin-binding proteins associated with mammalian DNA polymerase alpha.

Complex, multiprotein forms of bovine (calf thymus), hamster (Chinese hamster ovary cell), and human (HeLa) cell DNA polymerase alpha (Pol alpha) were analyzed for their content of calmodulin-binding proteins. The approach used an established autoradiographic technique employing 125I-labeled calmodulin to probe proteins in denaturing SDS-polyacrylamide gel electropherograms. All three Pol alpha enzymes were associated with discrete, Ca2+-dependent calmodulin-binding proteins. Conventionally purified calf thymus Pol alpha holoenzyme contained three prominent, trifluoperazine-sensitive species with apparent molecular masses of approx. 120, 80 and 48 kDa. The 120 and 48 kDa species remained associated with the polymerase.primase core of the calf enzyme during immunopurification with monoclonal antibodies directed specifically against the polymerase subunit. The patterns of the calmodulin-binding proteins displayed by conventionally purified preparations of hamster and human Pol alpha enzymes were similar to each other and distinctly different from the pattern of comparable preparations of calf thymus Pol alpha. Immunopurified preparations of the human and hamster Pol alphas retained significant calmodulin-binding activity of apparent molecular masses of approx. 55, 80 and 150-200 kDa.

Animals↗
PubMed1988

Identification and characterization of a DNA primase activity present in herpes simplex virus type 1-infected HeLa cells.

A novel DNA primase activity has been identified in HeLa cells infected with herpes simplex virus type 1 (HSV-1). Such an activity has not been detected in mock-infected cells. The primase activity coeluted with a portion of HSV-1 DNA polymerase from single-stranded DNA agarose columns loaded with high-salt extracts derived from infected cells. This DNA primase activity could be distinguished from host HeLa cell DNA primase by several criteria. First, the pH optimum of the HSV primase was relatively broad and peaked at 8.2 to 8.7 pH units. In contrast, the pH optimum of the HeLa DNA primase was very sharp and fell between pH 7.9 and 8.2. Second, freshly isolated HSV DNA primase was less salt sensitive than the HeLa primase and was eluted from single-stranded DNA agarose at higher salt concentrations than the host primase. Third, antibodies raised against individual peptides of the calf thymus DNA polymerase:primase complex cross-reacted with the HeLa primase but did not react with the HSV DNA primase. Fourth, freshly prepared HSV DNA primase appeared to be associated with the HSV polymerase, but after storage at 4 degrees C for several weeks, the DNA primase separated from the viral DNA polymerase. Separation or decoupling could also be achieved by gel filtration of the HSV polymerase:primase. This free DNA primase had an apparent molecular size of approximately 40 kilodaltons, whereas free HeLa DNA primase had an apparent molecular size of approximately 110 kilodaltons. On the basis of these data, we believe that the novel DNA primase activity in HSV-infected cells may be virus coded and that this enzyme represents a new and important function involved in the replication of HSV DNA.

DNA Primase↗
PubMed1986

Immunological analysis of the polypeptide structure of calf thymus DNA polymerase-primase complex.

Five major polypeptides are found in immunoaffinity-purified calf thymus DNA polymerase-DNA primase complex: 185, 160, 68, 55, and 48 kDa. Individual polypeptides purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used to produce antibodies in rabbits to aid in identifying the relationships between these polypeptides by immunoblotting and enzyme neutralization procedures. Immunoblot analyses showed that the 160-kDa peptide is derived from the 185-kDa peptide and the 48-kDa peptide is derived from the 68-kDa peptide while antibodies to the 55-kDa peptide do not cross-react with other peptides found in the complex. Direct enzyme neutralization studies demonstrated that antibodies to 185- and 160-kDa peptides inhibit DNA polymerase activity in the complex, confirming earlier suggestions that these peptides are the catalytic peptides for DNA polymerase. DNA primase activity in the complex is inhibited by antibodies to 68-, 55-, and 48-kDa peptides and to a lesser extent by antibodies to the 160-kDa peptide. Free DNA primase isolated from the complex was estimated to have a native molecular weight of about 110,000. The 55- and 48-kDa peptides are found to be associated with the free primase activity. Rabbit antibodies to both 55- and 48-kDa peptides are inhibitory to this primase activity. From these results we suggest that the native calf thymus DNA polymerase-DNA primase complex contains only three unique peptides with the 185-kDa peptide as the catalytic peptide of DNA polymerase and the 55- and 68-kDa peptides constituting the primase peptides. A model illustrating the roles of these peptides in initiation and replication of DNA is presented.

Animals↗
PubMed1985

Initiation of DNA synthesis by the calf thymus DNA polymerase-primase complex.

The calf thymus DNA polymerase-alpha-primase complex purified by immunoaffinity chromatography catalyzes the synthesis of RNA initiators on phi X174 single-stranded viral DNA that are efficiently elongated by the DNA polymerase. Trace amounts of ATP and GTP are incorporated into products that are full length double-stranded circular DNAs. When synthetic polydeoxynucleotides are used as templates, initiation and DNA synthesis occurs with both poly(dT) and poly(dC), but neither initiation nor DNA synthesis was observed with poly(dA) and poly(dI) templates. Nitrocellulose filter binding and sucrose gradient centrifugation studies show that the DNA polymerase-primase complex binds to deoxypyrimidine polymers, but not to deoxypurine polymers. Using d(pA)-50 with 3'-oligo(dC) tails and d(pI)-50 with 3'-oligo(dT) tails, initiator synthesis and incorporation of deoxynucleotide can be demonstrated when the average pyrimidine sequence lengths are 8 and 4, respectively. These results suggest that purine polydeoxynucleotides are used as templates by the DNA polymerase only after initiation has occurred on the oligodeoxypyrimidine sequence and that the pyrimidine stretch required by the primase activity is relatively short. Analysis of initiator chain length with poly(dC) as template showed a series of oligo(G) initiators of 19-27 nucleotides in the absence of dGTP, and 5-13 nucleotides in the presence of dGTP. The chain length of initiators synthesized by the complex when poly(dT) or oligodeoxythymidylate-tailed poly(dI) was used can be as short as a dinucleotide. Analysis of the products of replication of oligo(dC)-tailed poly(dA) shows that initiator with chain length as low as 4 can be used for initiation by the polymerase-primase complex.

Animals↗
PubMed1984

Isolation and partial characterization of DNA polymerases from Crithidia fasciculata.

Two types of DNA polymerase activity were partially purified from Crithidia fasciculata. The alpha-type, DNA polymerase A, was of high molecular weight and sensitive to N-ethylmaleimide, whereas the beta-type, DNA polymerase B, was of low molecular weight and resistant to N-ethylmaleimide. Phosphocellulose chromatography revealed multiple peaks of DNA polymerase A activity the properties of which, such as pH optimum, salt sensitivity, utilization of synthetic template-initiator complexes and response to DNA polymerase inhibitors were similar. The response of the C. fasciculata DNA polymerase A enzymes to some of these inhibitors and utilization of poly(rA) X oligo(dT)11 showed these enzymes to be markedly different from mammalian DNA polymerase alpha.

Animals↗