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Biomedical subjects

D Pratt

Publications and source records attributed to D Pratt.

At least 55 records · Page 3Linked to original sources
PubMed1992

Standardization of hysterosalpingography and selective salpingography: a valuable adjunct to simple opacification studies.

OBJECTIVE: To investigate the correlation between opacification and perfusion pressures during hysterosalpingography (HSG) and selective salpingography under the assumption that the latter may add to the diagnostic capabilities of the procedures. DESIGN: Perfusion pressures were uniformly evaluated by standardizing injection volume per time interval of contrast medium and the delivery system. Pressures were measured in a closed system through a digital manometer and recorded on tracing paper. SETTING: Fully ambulatory gynecoradiology suite at academically affiliated infertility center. PATIENTS: Thirty infertility patients. INTERVENTION: Hysterosalpingography and selective salpingography for diagnostic purposes. MAIN OUTCOME MEASURE: Correlation between opacification patterns and perfusion pressures. RESULTS: The evaluation of perfusion pressures during HSG is unreliable because they may be affected by uterine factors and will only reflect the oviduct of least resistance. In contrast, perfusion pressures during selective salpingography are reflective of only the investigated tube. They appear to lie within a functionally normal range of up to 350 mm Hg. Tubes by opacification judged as normal exhibited a pressure range of 429 +/- 376 mm Hg, which was significantly lower than that of abnormally appearing oviducts (957 +/- 445 mm Hg; P = 0.001). CONCLUSIONS: The concomitant performance of perfusion pressure studies during selective salpingography further enhances the diagnostic capability of selective salpingography over HSG in the diagnostic evaluation of fallopian tubes.

Female↗
PubMed1992

Rotavirus diarrhoea in children in the highlands of Papua New Guinea.

Children from the highlands of Papua New Guinea, hospitalized for severe diarrhoea, were examined for clinical signs and the presence of rotaviruses. Rotavirus was detected in faecal samples from 68% (23/38) of patients examined. In contrast to other studies, an excess of respiratory symptoms was not observed and the infection rate of disease due to rotavirus was relatively high in children under 6 months of age. In an environment where pigs and humans share close contact a rotavirus strain infecting piglets was also demonstrated.

Animals↗
PubMed1990

Antiretroviral activity of synthetic hypericin and related analogs.

Hypericin and pseudohypericin are naturally occurring polycyclic quinones which have recently been shown to inhibit the infectivity of several retroviruses, including human immunodeficiency virus. To better understand the antiviral mechanisms of these compounds, hypericin and a series of analogous quinones were synthesized and tested for anti-retroviral activity against equine infectious anemia virus (EIAV). Treatment of EIAV-infected cells with hypericin reduced the production of infectious virus by 99.99%. None of the analogs were found to inhibit virus replication. These results suggest that the complete ring structure of hypericin is required, but not sufficient, for antiviral activity.

Animals↗
PubMed1990

Molecular cloning and primary sequence of a cysteine protease expressed by Haemonchus contortus adult worms.

We have cloned cDNAs encoding a 35-kilodalton cysteine protease that is a major component of protective extracts isolated from blood-feeding Haemonchus contortus adult worms. Near full-length cDNAs for the protease were isolated by immunoscreening an adult worm cDNA expression library with a rabbit antiserum prepared against the protein eluted from preparative SDS gels and by rescreening the library with oligonucleotide probes. The protein predicted from the nucleotide sequence of the cDNAs and of a genomic DNA clone comprises 342 amino acids and contains an N-terminal signal sequence, 16 cysteine residues and four potential N-linked glycosylation sites. The enzyme appears to be glycosylated in vivo. The H. contortus protease, called AC-1, displays an overall 42% sequence identity with the human lysosomal thiol protease cathepsin B. The similarities between cathepsin B and AC-1 are localized primarily to regions of cathepsin B that comprise the mature, active form of the enzyme. A stretch of six amino acids that includes the active site cysteine of cathepsin B is conserved, and is present in the same relative location in AC-1, suggesting that this region comprises the active site of the H. contortus enzyme.

Amino Acid Sequence↗
PubMed1990

A developmentally regulated cysteine protease gene family in Haemonchus contortus.

The nucleotide sequence of a gene encoding a 35-kDa thiol protease of the parasitic nematode Haemonchus contortus has been determined. The gene, designated AC-2, shares 97% nucleotide sequence identity and 98% amino acid identity with previously characterized AC-1 cDNAs encoding the thiol protease. The AC-2 gene spans 8 kb and appears to contain 11 introns, ranging in size from 57 bp to over 5.2 kb. One of the introns interrupts the proposed active site region that is conserved between the H. contortus protease and the related thiol proteases cathepsin B and papain. Southern blot hybridization experiments indicate that the protease is encoded by a small gene family in H. contortus. Rabbit antisera prepared against the recombinant protein react on Western blots with 35 and 37-kDa proteins of adult worms. These proteins were not detectable by Western blot analysis in three larval parasitic developmental stages of H. contortus. Northern blot hybridizations indicate that mRNA transcripts for the gene family are present at low levels in a mixed population of third- and fourth-stage larvae but highly abundant in adult worms. Expression of the protease correlates with blood-feeding and suggests a role for the protease in blood digestion.

Amino Acid Sequence↗
PubMed1989

Cuticle collagen genes of Haemonchus contortus and Caenorhabditis elegans are highly conserved.

Several genes and partial cDNAs encoding cuticle collagens have been isolated from the sheep parasitic nematode Haemonchus contortus. DNA sequencing and Southern blot hybridization studies reveal that H. contortus collagens comprise a large family of related, but non-identical genes. The genes appear to be dispersed throughout the genome. The predominant size of collagen mRNA in molting worms was found to be between 1.0 and 1.2 kb. The one complete gene that was sequenced contains two short introns and encodes a protein of about 300 amino acids. The predicted protein sequence contain several (Gly-X-Y)n triple helix-coding domains that are interrupted by short stretches of non-helix-coding amino acids. The size of the predicted protein and the organization of the triple-helix coding domains are similar to that of Caenorhabditis elegans collagens. All the H. contortus genes studied show a striking homology to the C. elegans collagen gene subfamily represented by col-1. In particular, the amino acid sequence of the carboxy-terminal non-(Gly-X-Y)n region and the positions of cysteine residues flanking the (Gly-X-Y)n domains were found to be highly conserved in the collagens of these two nematodes.

Amino Acid Sequence↗
PubMed1988

Five distinct calcium and phospholipid binding proteins share homology with lipocortin I.

We have purified two 35-kDa proteins from rat peritoneal lavages that inhibit phospholipase A2 activity. Both are calcium/phospholipid-dependent membrane binding proteins and share similar structural and biochemical properties with lipocortins I and II. By sequence analysis we confirmed that they are lipocortin-related, and we refer to the two inhibitors as lipocortins III and V. Using partial sequence information obtained from the purified rat proteins, full length cDNA clones for both proteins and for their human counterparts were isolated. As with lipocortins I and II, the amino acid sequences of lipocortins III and V which were deduced from the cDNA clones are highly conserved, sharing 50% identity with other family members. Related proteins were also purified from bovine intestinal mucosa and characterized by peptide mapping, sequence, and immunological analyses. In addition to lipocortins III and V the bovine preparation contained a third 35-kDa inhibitor and a 68-kDa inhibitor, extending the number of known lipocortins to six distinct proteins. While the various lipocortins are structurally similar, distinct differences in their cellular distribution indicate specialized roles for the individual proteins.

Amino Acid Sequence↗
PubMed1987

Mobility.

Explore the source record for details and available documents.

Automobile Driving↗
PubMed1986

Immunological and colorimetric determination of prostatic acid phosphatase--technical and clinical reappraisal in symptomatic patients.

We compared a selection of quantitative immunological methods for prostatic acid phosphatase (PAP) with routine colorimetric assays for total and tartrate-labile acid phosphatase and evaluated their relative clinical merits in the differential diagnosis of prostatic carcinoma. We also assessed a wide range of commercial control materials for suitability of use with these methods. Patients studied included 111 cases of prostatic carcinoma, 42 cases of benign prostatic hyperplasia, and 33 controls. The principles of the methods used included determination of enzymatic activity using p-nitrophenyl phosphate, RIA, immunoradiometric, and enzymoimmunometric assays. Performance characteristics for the immunological methods were inferior to manufacturers' precision and specificity claims. We identified control materials that were unsuitable for routine use. Poor discrimination between clinical groups was observed for all methods. Analysis by use of a receiver operator characteristic plot failed to improve this. We conclude that the immunological methods we studied offer no advantages over colorimetric methods in the differential diagnosis of prostatic cancer in symptomatic patients.

Acid Phosphatase↗
PubMed1985

Rapid measurement of creatine kinase activity in a coronary care unit using a portable benchtop reflectance photometer.

Rapid measurements of plasma creatine kinase activity using an inexpensive benchtop reflectance photometer (Ames Seralyzer) and disposable reagent strips were evaluated in the laboratory and coronary care unit. The system proved simple to use and capable of yielding rapid (four minutes per analysis), precise (coefficient of variation less than 9%), and accurate results (correlation with routine method 0.995) when used by medical staff. Creatine kinase values were available 6.5-102 hours earlier than routine laboratory data, depending on the time and day of sampling, thereby facilitating appropriate and economic patient management. This instrument might be used to supplement the routine enzyme service for selected admissions, resulting in greatly improved availability of results and hence contributing to the early discharge of patients from intensive care facilities.

Clinical Enzyme Tests↗
PubMed1985

The comparative properties of plaster of Paris and plaster of Paris substitutes.

Modern casting materials are becoming available in an increasing and bewildering variety. A series of tests has been devised to investigate the properties of these materials. They have been tested for strength, flexibility, lamination, fatigue life and radiolucency. Their properties have been compared with those of plaster of Paris in order that the role of the newer materials can be defined. It is suggested that the tests described might form the basis of a standard from which user trials could be designed to appraise the value of these materials in clinical practice.

Calcium Sulfate↗
PubMed1985

Rapid ward assessment of renal function by reflectance photometric determination of plasma creatinine.

The Ames Seralyzer reflectance photometer and disposable reagent strips for the determination of plasma creatinine were evaluated in the laboratory and on a urology ward over a 3-month period. Principles of the instrument used are described, as are details of the evaluation procedures. Reproducibility of results under optimum conditions gave coefficients of variation less than 7%. Under routine conditions of use, medical staff and laboratory analysts achieved high correlation with the routine laboratory method of analysis (r = 0.986, N = 108: r = 0.996, N = 102 respectively). Potential sources of inaccuracy were identified. Seralyzer determination of plasma creatinine can be rapidly, simply and reliably performed by medical staff on a urology ward, thereby facilitating assessment of renal function governed by clinical requirement rather than by laboratory convenience.

Creatinine↗
PubMed1985

Influenza surveillance: alternative laboratory techniques for a developing country.

In developing countries it is often impractical to use conventional methods to isolate and identify influenza viruses. The use of trypsin-treated LLC-MK2 cells for the isolation of myxoviruses, in conjunction with the indirect fluorescent antibody technique for identification of isolates and for direct detection of viral antigens in specimens, was an effective combination of techniques which enabled our laboratory in Papua New Guinea to participate in an influenza surveillance programme. The application of these techniques in routine respiratory virus surveillance and in the investigation of an outbreak of influenza-like illness is described.

Child↗
PubMed1983

Nucleotide sequence of the Escherichia coli xanthine-guanine phosphoribosyl transferase gene.

The Escherichia coli gene coding for the enzyme xanthine-guanine phosphoribosyl transferase (gpt) has been widely used as a dominant selectable marker in a variety of mammalian cells. We have determined the complete nucleotide sequence of the 1057 base pair (bp) segment of DNA containing this gene. The coding sequence for the enzyme is 456 nucleotides long and can code for a 152 amino acid (16.9 Kd) polypeptide. A comparison of the amino acid sequence of the bacterial enzyme with that of the mammalian hypoxanthine-guanine phosphoribosyl transferase (hprt) reveals no significant homology between the two polypeptides.

Amino Acid Sequence↗
PubMed1983

Educational contracts: a basis for effective clinical teaching.

An educational contract is a negotiated agreement between a teacher and a learner. It addresses four elements: needs, expectations, roles, and content. Contracts should develop and evolve via explicit negotiation between the teacher and the learner. Research to validate the concept of the educational contract and to document its utility is important to understanding effective clinical teaching.

Faculty, Medical↗
PubMed1982

Liposome dialysis for improved size distributions.

A technique is described which allows reproducible preparation of liposomes with improved size-frequency distributions. The recent procedure of extrusion of crude liposome dispersions through controlled-pore polycarbonate membranes is used to control the upper limit of liposome diameter. Subsequent dialysis, using the same type of membrane, can remove the majority of liposomes smaller than a predetermined size. The pattern of dialysis of a liposome preparation is a function of the size-frequency distribution (as well as the membrane pore size) and can be used to approximate the distribution and/or used to monitor the reproducibility of liposome preparations.

Chemical Phenomena↗
PubMed1980

Folded chromosomes of Saccharomyces cerevisiae: comparison of response to sporulation medium, arrest at start, and G0 arrest.

Folded chromosome phenotypes have been examined and compared in four cell-division-cycle (cdc) mutants during transitions between cycling and non-cycling states. The two start mutants, cdc 28 and cdc 25, can undergo G0 arrest at the restrictive temperature. Arrest at start, defined by the cdc 28 and cdc 25 block points, is distinguishable from G0 arrest. Arrest at the cdc 28 and cdc 25 block points can also be distinguished from each other: folded chromosomes appear to be destabilized at the cdc 25 block, but are stable at the cdc 28 arrest point. On the other hand, folded chromosomes from cdc 28 in sporulation medium at the restrictive temperature appear unstable, while chromosomes from cdc 25 are stable. The G1 arrest mutants, cdc 4 and cdc 7, can undergo G0 arrest at the restrictive temperature. In sporulation medium no meiotic replication form is detected at the restrictive temperature, although incorporation of labeled precursors into nuclear DNA does take place. A schematic model incorporating these various findings is presented.

Chromosomes↗