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Biomedical subjects

S Watkins

Publications and source records attributed to S Watkins.

At least 109 records · Page 6Linked to original sources
PubMed1991

Elevated urinary excretion of the C5b-9 complex in membranous nephropathy.

In experimental membranous nephropathy, antibody binding to glomerular epithelial cell membrane antigens results in complement activation and formation of complement C5b-9 membrane attack complexes in glomeruli. During active disease, the C5b-9 complexes are shed into the urine. To test the hypothesis that a similar mechanism might be operative in human membranous nephropathy, we measured urinary excretion of C5b-9 and C5 in 146 proteinuric patients with biopsy-proven glomerular diseases or diabetes mellitus. Urinary excretion of C5b-9 relative to C5 excretion was higher in 40 patients with membranous nephropathy than in 106 patients with proteinuria due to non-membranous glomerulonephritis when analyzed by covariance analysis (P less than 0.0002). Urinary C5b-9 excretion was higher in membranous nephropathy than in membranoproliferative glomerulonephritis (N = 13, P less than 0.05), minimal change-focal sclerosis (N = 33, P less than 0.001), mesangial proliferative glomerulonephritis (N = 9, P less than 0.02) and IgA nephropathy (N = 7, P less than 0.025). Urinary C5b-9 excretion was also higher in patients with lupus nephritis (N = 18, P less than 0.02) compared to those with non-membranous glomerulonephritis. The lupus patients with the highest excretion had clinical or pathological features of membranous nephropathy. Nine patients with membranous nephropathy and elevated urinary C5b-9 excretion had a shorter duration of disease (P less than 0.05), lower serum creatinine levels (P less than 0.05) and more proteinuria (P less than 0.02) than the 31 membranous nephropathy patients with normal values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

The measurement of ox corneal swelling pressure by osmometry.

1. Ox corneal stromal swelling pressure (gel pressure) may be measured by osmometry: polyethylene glycol of nominal molecular mass 10,000 Da (PEG 10K) is a suitable non-penetrating solute. 2. Corneal hydrations equilibrate within 4 h of exposure to 154 mM-NaCl including various concentrations (2-8%) of PEG 10K, providing that the epithelium covers the anterior surface and Descemet's membrane covers the posterior surface. At equilibrium hydration, corneal gel pressure equals the external osmotic pressure contributed by PEG 10K. 3. The osmotic pressure of PEG 10K may be calibrated using Descemet's membrane as the semi-permeable membrane. 4. Corneal gel pressure decreases with increasing hydration. 5. The relationship may be adequately explained by the Donnan theory of corneal swelling with a fixed negative matrix charge of 39.5 +/- 0.8 mequiv l-1 at physiological hydration of 3.2 at this salt concentration (154 mM-NaCl).

Animals↗
PubMed1991

Nuclear assembly of polyomavirus capsids in insect cells expressing the major capsid protein VP1.

Polyomavirus normally assembles in the nucleus of infected mouse cells. Sf9 insect cells expressing the polyomavirus major capsid protein VP1 were examined by electron microscopy. Capsidlike particles of apparently uniform size were found in the nucleus. Immunogold electron microscopy demonstrated abundant VP1 in the cytoplasm which was not assembled into any recognizable higher-order structure. Cytoplasmic VP1 assembled after the cells were treated with the calcium ionophore ionomycin. Purified VP1 aggregates were shown by negative staining and cryoelectron microscopy to consist predominantly of particles similar to the empty T = 7 viral capsid. Thus, polyomavirus VP1 can assemble in vivo into capsids independent of other viral proteins or DNA. Nuclear assembly may result from increased available calcium in this subcellular compartment.

Animals↗
PubMed1991

A coactive sign system for children who are dual-sensory impaired.

The SKI*HI Institute developed a system of coactive signing to help alleviate communication and instructional barriers for children who are dual-sensory impaired (deaf and blind). The system also can be used to help children who are severely multihandicapped learn how to communicate. The system includes optimized coactive signs that are functional, easy to feel, easy to relate to the referent, and easy to make, and it also includes techniques related to effective coactive sign use. The coactive sign system is illustrated on a series of video tapes that has been field tested and produced and is being disseminated throughout the United States and Canada.

Blindness↗
PubMed1990

Comparisons of plasma and salivary cortisol determinations for the diagnostic efficacy of the dexamethasone suppression test.

The current status of the saliva dexamethasone suppression test (DST) is discussed and results from the literature reviewed. Evidence is presented that demonstrates that the efficacy of the salivary-based test is equal to that of the plasma DST provided that specifically developed radioimmunoassays are used for determination of salivary cortisol. Such evidence relied on measurement of cortisol in 300 matched samples of plasma and saliva provided by patients admitted to a routine psychiatric ward over a 2-year period. The results according to diagnosis (DSM-III categories) were in line with those generally reported. The influence of anticholinergic medication was examined: this had no significant effects on the performance of the plasma or salivary-based DST.

Depressive Disorder↗
PubMed1990

A monoclonal antibody reactive with a 15-kDa cytoplasmic granule-associated protein defines a subpopulation of CD8+ T lymphocytes.

We have recently described a novel method for the production and characterization of mAb reactive with T cell-restricted intracellular antigens. From a panel of antibodies that react specifically with permeabilized T lymphocytes but not with permeabilized B lymphocytes or native T cells, we have selected one, designated TIA-1, that reacts with 20 to 36% of digitonin permeabilized peripheral blood T lymphocytes. Flow cytometric analysis of purified CD4+ and CD8+ subsets showed TIA-1 to recognize a subpopulation of 49 to 64% of CD8+ lymphocytes. Little or no reactivity with CD4+ resting T lymphocytes was observed. TIA-1 did not react with any of a panel of T cell lines, B cell lines, or monocytoid cell lines. TIA-1 reacted strongly with NK cell clones and CD8+ cytolytic T cell clones, and less strongly with CD4+-activated T cell clones, suggesting a preferential expression in cells possessing cytolytic potential. Cell fractionation experiments showed TIA-1 to be membrane associated. Furthermore, Percoll gradient fractionation of a cytolytic T cell clone (T4T8C1) showed the majority of TIA-1 to be contained in a low density membrane fraction that also contained serine protease activity. Immunoelectron microscopy showed TIA-1 to decorate the membranes of electron lucent and electron dense cytoplasmic granules in this same cytolytic T cell clone. Biochemical analysis showed TIA-1 to be a 15-kDa protein in unstimulated T cells. Upon activation with Con A or anti-CD3 antibodies. TIA-1 was induced to form disulfide linked dimers, trimers, and tetramers of the basic 15-kDa unit. Taken together, our data suggest that TIA-1 is a cytolytic granule associated protein that may define a subpopulation of resting CD8+ T lymphocytes possessing cytolytic potential.

Antibodies, Monoclonal↗
PubMed1990

Comprehensive management of renal failure in infants.

From 1986 through 1989, 23 infants (18 of whom were less than 30 days old) required peritoneal dialysis within their first 6 months of life. Modifications to conventional peritoneal dialysis included modified Silastic Tenckhoff catheters, peel-away sheaths for percutaneous insertion, automated peritoneal dialysis "cyclers," and generous omentectomy. With these modifications, there were no bowel perforations, and the infants were successfully dialyzed for prolonged periods. Eight of the 23 infants developed end-stage renal failure and were prepared for transplantation. All had gastrostomy tubes placed to supplement oral nutrition. Living, related transplantation was performed when the child weighted 10 kg. Four of the eight completed this protocol. One child with congenital nephrotic syndrome died before transplantation. One transplant was complicated by a technical problem (venous thrombosis), which resulted in allograft loss and return to peritoneal dialysis. Kidney function, growth, and development in the survivors were excellent.

Catheters, Indwelling↗
PubMed1990

Seasonal variation and the results of the dexamethasone suppression test.

There is controversy over the presence of a circannual rhythm in cortisol values in samples provided by depressed patients after a standard dexamethasone suppression test (DST). Post-DST cortisol values from patients admitted to an acute psychiatric ward over a 2-year period have therefore been analysed by appropriate statistical tests. No evidence was found for significant seasonal variation.

Depressive Disorder↗
PubMed1990

Hypermutability of CpG dinucleotides in the propeptide-encoding sequence of the human albumin gene.

An electrophoretically slow albumin variant was detected with a phenotype frequency of about 1:1000 in Sweden and was also found in a family of Scottish descent from Kaikoura, New Zealand, and in five families in Tradate, Italy. Structural study established that the major variant component was arginyl-albumin, in which arginine at the -1 position of the propeptide is still attached to the processed albumin. A minor component with the amino-terminal sequence of proalbumin was also present as 3-6% of the total albumin. After amplification of the gene segment encoding the prepro sequence of albumin, specific hybridization of DNA to an oligonucleotide probe encoding cysteine at position -2 indicated the mutation of arginine at the -2 position to cysteine (-2 Arg----Cys). This produced the propeptide sequence Arg-Gly-Val-Phe-Cys-Arg. This was confirmed by sequence analysis after pyridylethylation of the cysteine. This mutation produces an alternate signal peptidase cleavage site in the variant proalbumin precursor of arginyl-albumin giving rise to two possible products, arginyl-albumin and the variant proalbumin. Another plasma from Bremen had an alloalbumin with a previously described substitution (1 Asp----Val), which also affects propeptide cleavage. Hypermutability of two CpG dinucleotides in the codons for the diarginyl sequence may account for the frequency of mutations in the propeptide. Mutation at these two sites results in a series of recurrent proalbumin variants that have arisen independently in diverse populations.

Amino Acid Sequence↗
PubMed1990

Mutations in genetic variants of human serum albumin found in Italy.

A long-term electrophoretic survey of genetic variants of serum albumin has identified an alloalbumin in 589 unrelated individuals in Italy. The alloalbumins were classified electrophoretically into 17 types. The number of unrelated carriers for each type varied from 1 for several variants reported here to 103 for albumin B. The structural change in 8 of these types has previously been determined, and the amino acid substitutions in 3 additional types are reported here. Albumin Varese has a substitution, -2 arginine to histidine (-2 Arg----His), the same as that reported for proalbumin Lille; albumin Torino has the substitution 60 Glu----Lys; and albumin Vibo Valentia has the substitution 82 Glu----Lys. The ability to distinguish so many alloalbumin types by electrophoresis at several pH values indicates that similar substitutions at different sites produce variants with different electrophoretic mobilities. Except for chain terminations in two Italian variants, all the mutations thus far determined for alloalbumins are attributable to a single-base change in the structural gene, and there is a preponderance of transitions and purine mutations. Seven alloalbumins for which the structural change has been established have been ascertained only in Italy. Several of these are clustered in specific geographic regions of Italy, which suggests an origin through a founder individual. Other variants that occur worldwide are nonetheless clustered in geographic regions within Italy. In these cases an independent mutation probably occurred at a hypermutable site such as a CpG dinucleotide.

Amino Acid Sequence↗
PubMed1990

Burke Rehabilitation Center. A homemaker-home health aide program for disadvantaged adults.

In response to an area shortage of homemaker-home health aides, the Burke Rehabilitation Center has instituted a training program for financially disadvantaged persons, teaching them work in a home setting, caring for the frail elderly, children, and/or mentally impaired individuals. Both clients and homemaker-home health aides have benefited from this innovative program.

Adolescent↗
PubMed1989

Survey of equipment in general practice.

Partners in general practice have to buy any equipment they want themselves. As a result partners in high investing practices have lower net incomes. Of the 297 practices in Devon and Cornwall, 265 responded to a questionnaire listing 115 possible items of practice equipment. Overall, practices seemed to be fairly well equipped. Key findings were that 193 of those who responded had an electrocardiograph, 206 had a kit for minor operations, 119 owned a computer, and less than one third owned a microscope. Most of these practices were high investors. There seems to be a shift away from some traditional instruments towards expensive information technology. Government policies are encouraging the use of computers and such equipment, though funds are not necessarily being made available for this purpose.

Electrocardiography↗
PubMed1989

Unpack the package.

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Hospitals, Public↗
PubMed1989

Measured energy expenditure in pediatric intensive care patients.

Few data are available on energy requirements of mechanically ventilated, critically ill children. We measured the resting energy expenditure in 18 mechanically ventilated patients between ages 2 and 18 years, using indirect calorimetry. All patients had fractional inspired oxygen concentration less than 0.6, no spontaneous respirations, hemodynamic stability, and no fever or active infection, and were receiving 5% dextrose. All subjects were hypermetabolic, since the measured resting energy expenditure divided by the predicted basal energy expenditure from the Harris-Benedict equations was 1.48 +/- 0.09 (mean +/- SEM). The energy requirements calculated using "injury factors" and "activity factors" adapted for adults is 1.62 times basal energy expenditure. The injury factor for the pediatric multiple trauma patients should be 1.25 compared with 1.35 in adults. In these pediatric intensive care patients 33% +/- 8% of the energy is derived from carbohydrates, 53% +/- 8% from fat, and 14% +/- 2% from protein oxidation. In individual critically ill pediatric patients, energy requirements should be estimated by measuring their resting energy expenditure whenever possible and adding 5% for their activity. In the absence of the actual measurement of resting energy expenditure, the recommended energy requirement is 1.5 times basal energy expenditure. In this acute phase of injury, the daily nitrogen requirement is 250 mg per kilogram of body weight.

Adolescent↗
PubMed1988

Receptor-like nature of class I HLA: endocytosis via coated pits.

The present investigations show that class I HLA are internalized by macrophage/monocyte type cells. Anti-class I antibody-binding assays show that about 30% of class I Ag present on cell surface are endocytosed within 1 h. Electronmicroscopic investigations reveal that, like other well established receptor molecules, internalization of HLA is mediated by coated pits and coated vesicles. The endocytosed Ag are transferred from endosomes to trans-Golgi reticulum and trans-Golgi cisternae, suggesting recycling of these Ag back to the cell surface. In the presence of phorbol ester tetradecanoyl phorbol acetate, there is a modest increase in the rate of internalization. These results are consistent with the hypothesis that class I Ag on monocytes/macrophages behave like receptor molecules. Malignant transformation of monocytic cells apparently causes the loss of this property of class I Ag.

Antigens, Surface↗