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Biomedical subjects

J Hamilton

Publications and source records attributed to J Hamilton.

At least 145 records · Page 8Linked to original sources
PubMed1991

Equine neural angiostrongylosis.

Verminous encephalomyelitis due to Angiostrongylus cantonensis larvae was diagnosed in 2 foals at necropsy. The principal clinical feature was tetraparesis, although history and neurological examination revealed progressive and multifocal neurological disease. At presentation, a tentative diagnosis of parasitic larval migration involving the central nervous system (CNS), presumably due to Strongylus vulgaris, was proposed. Dissection of the spinal cord in one case resulted in recovery of intact larvae of both sexes of A. cantonensis. In both foals, histopathology of the brain and spinal cord revealed nematode sections which were consistent with A. cantonensis larvae.

Angiostrongylus↗
PubMed1991

Measuring the efficiency of an artificial lung: 1. Carbon dioxide transfer.

The performance of a hollow fibre artificial lung ('Capiox E') was analysed by measurement of the 'parallel deadspace' of the device under varying conditions in 21 patients. The efficiency with which carbon dioxide was exchanged was determined by the time available for equilibration between the blood and gas phases. When this equilibration coefficient was less than 12 seconds per litre of blood flow per litre of gas flow, there was a marked reduction in the efficiency of gas exchange. Under certain conditions, the 'counter-current' design of the device apparently permitted the clearance of carbon dioxide at a partial pressure greater than that which was found in the mixed venous blood. This anomalous behaviour may represent in vivo confirmation of the Haldane effect.

Adult↗
PubMed1990

The isolation and partial characterization of bovine parathyroid secretory granules.

We have developed a procedure which allows the isolation of secretion granules from fresh parathyroid glands. Following collagenase digestion of the tissue, the cells were broken with osmotic shock and a crude granule/mitochondrial pellet was obtained by differential centrifugation. Before loading this fraction onto a metrizamide density gradient it was subjected to brief sonication to disrupt the mitochondria. This procedure was necessary in order to achieve separation of the granules from the mitochondria during ultracentrifugation of the gradient. When the fractionated gradient was analysed for PTH by radioimmunoassay, three bands containing parathyroid hormone were found, at densities of 1.0, 1.05 and 1.18. Upon electron microscopic examination of the gradient fractions, granules were found only in those fractions containing hormone. A typical granule appearance was observed for two of the populations, but the third population (density 1.18), consisted of granules without membranes and which appeared less electron dense than those of populations 1 (density of 1.0) and 2 (density of 1.05). Moreover, the lack of a limiting membrane imparted a fuzzy appearance to the population 3 granules. When fresh tissue sections were examined as control samples, granules with and without membranes were also observed. Standard marker enzyme assays further confirmed that populations 2 and 3 were relatively free of other cellular contaminants, but population 1 contained endoplasmic reticulum and lysosomal material. Because the number of granules contained in this population is very small, we have not been successful in achieving further purification of population 1. Based on radioimmunoassay of extracts of each granule population, PTH was concentrated in population 3, while the other two contained lesser amounts. Interestingly, results obtained with a radioimmunoassay for SP-1 revealed a striking difference in the distribution of SP-1 in the three granule populations. This protein, which is also secreted by the parathyroid gland, was concentrated in population 1 and 2. Only very low levels were found in population 3. Thus, the two major secretory products are localized in different granule populations. The isolated granules were stable to pH changes, cycles of freeze/thaw and sonication. The yields of PTH extracted from each of the granule populations by freezing and thawing in buffer or by Triton containing solutions were low. PTH was completely extracted from each population only by using 8 M urea in HCl. Lower concentrations of urea were less effective. These results indicate that the molecular architecture of the granules is highly resistant to disruption.

Animals↗
PubMed1989

Effects of parathyroid hormone on cyclic-AMP concentrations of in vitro Necturus maculosus gastric antrum.

The effects of bovine parathyroid hormone (bPTH1-84) on the stimulation of intracellular cyclic-AMP [cAMP] were investigated in an in vitro preparation of Necturus maculosus antral mucosa. When the antrum was exposed to 1, 5, 10, or 100 nM bPTH1-84, there was an approximately 2-fold nonlinear increase in tissue [cAMP] over basal values. The pretreatment of the antral mucosa with 1 mM isobutylmethylxanthine (IBMX, a phosphodiesterase inhibitor) increased with detectability of mucosal [cAMP]. The addition of 1, 5, 10, or 100 nM bPTH1-84 to tissues pretreated with IBMX resulted in an approximately 3.5-fold linear increase in mucosal [cAMP] over basal values. The time course of the generation of mucosal cAMP to 10 nM bPTH1-84 resulted in a small but significant transient increase at 2.5 min after the addition of bPTH1-84 but no change in the medium [cAMP]. In tissues pretreated with 1 mM IBMX the response to 10 nM bPTH1-84 was a large biphasic increase of [cAMP] at 2.5 min that progressively declined to near basal values by 15 min. There was also a significant sustained increase in the [cAMP] in the bathing medium at 2.5 min of tissues pretreated with IBMX followed by 10 nM bPTH1-84. These results suggest the presence of an adenylate cyclase that can be activated by a mammalian bPTH1-84 in elevating intracellular cAMP levels in the N. maculosus antral mucosa.

1-Methyl-3-isobutylxanthine↗
PubMed1989

Incidence of cardiac arrhythmias associated with mild hypokalemia induced by low-dose diuretic therapy for hypertension.

Nineteen men with mild to moderate hypertension and without a history of cardiac arrhythmias were randomized (double-blind) into groups to receive hydrochlorothiazide (HCTZ) at a dose of 25 mg/day, HCTZ at 50 mg/day, or HCTZ (25 mg) plus triamterene (50 mg) for a six-month period after a three-week (single-blind) placebo period. Serum electrolyte values were determined at baseline and at frequent intervals thereafter. Twenty-four hour ambulatory electrocardiograms were obtained at baseline and just before study termination. Mild hypokalemia (less than 3.5 mEq/L) occurred in approximately half of the patients and was unrelated to treatment group. Serious arrhythmias were infrequent, though some patients had large numbers of extra beats. The incidence of arrhythmia appeared unrelated to serum potassium concentration. We conclude that mild hypokalemia associated with low-dose diuretic therapy for hypertension is not arrhythmogenic.

Adult↗
PubMed1989

Comfort and the hospitalized chronically ill.

1. Although comfort is a word nurses use in their daily practice to describe a nursing measure, an outcome, and a goal, there has been very little research to determine the meaning of comfort from the patient's perspective. 2. The institutionalized elderly in this study described their comfort according to five themes: disease process; self-esteem; positioning; approach and attitudes of staff; and hospital life. So, as well as the physical component of comfort, the elderly viewed their comfort equally in terms of their relationships with others, their environment, and their feelings. 3. In order to best meet the patient's needs for comfort, the nurse should clarify the meaning of comfort with the patient so that he/she may individualize care.

Aged↗
PubMed1989

Efficacy and safety of isradipine in hypertension.

Of the calcium channel blocking drugs, only verapamil is approved in the United States for treatment of hypertension. Isradipine is a 1,4-dihydropyridine calcium blocker that may be given on a twice-daily basis. It causes peripheral vasodilation with minimal cardiodepressant activity. We undertook a double-blind, parallel group randomized, multicenter study of 203 hypertensive subjects to examine the efficacy and safety of isradipine in treatment of hypertension. Subjects were given 0, 2.5, 5, 7.5, or 10 mg isradipine twice daily for up to 5 weeks. There was a significant dose-response relationship between isradipine dose and decrease in systolic blood pressure (SBP) and diastolic blood pressure (DBP). Isradipine 15 mg/day reduced supine pressure by 16/15 mm Hg in patients with starting DBP less than 105 mm Hg and by 38/22 mm Hg in those with starting DBP greater than or equal to 105 mm Hg. There was no significant orthostatic fall in blood pressure at any dose. Heart rate (HR) increased on an average by only a maximum of four beats/min. The drug was slightly more effective in the elderly in the standing position than in the young in the standing position. Adverse effects were mild, and only six patients were discontinued from the study because of adverse effects. Isradipine appears to be a safe, effective drug in monotherapy of hypertension at a wide range of patient ages.

Adolescent↗
PubMed1989

Validity of messages from quadriplegic persons with cerebral palsy.

Interpreting gestures from retarded, nonvocal subjects is scientifically risky. Investigators must construe the subject's meaning without reference to an external validity measure. A procedure was devised in which message content was provided to nonvocal, severely palsied quadriplegic subjects in advance. Subjects' responses were limited to yes/no gestures. Another investigator elicited the messages without prior knowledge of their content. Results, which indicated reasonably high correspondence between stimulus messages and messages elicited, suggest that such subjects can present the content of their own phenomenal field accurately and that investigators' interpretations need not be considered imaginary.

Adult↗
PubMed1989

Anatomically correct dolls used in interviews of young children suspected of having been sexually abused.

To determine the value of using anatomically correct dolls in diagnostic interviews of young children suspected of being sexually abused, the records of 83 children who were less than 7 years of age and who were evaluated at Yale-New Haven Hospital because of a suspicion of sexual abuse were reviewed. The dolls were used in 60 cases (72%). When the dolls were used, children provided significantly more information than by interview alone about what had happened and about the identity of the suspected perpetrator. Children less than 3 years of age, however, were unable to provide details about the abuse despite the use of the dolls. The ratings of the likelihood that sexual abuse had occurred were based on all of the information in the case including that obtained through the diagnostic interview with the dolls. When these ratings were compared with the ratings based on evidence obtained solely from noninterview data, the likelihood of abuse was higher in 35% of the cases. It was concluded that substantially more information is provided by young children when anatomically correct dolls are used and that the likelihood of detection of abuse is increased when information from the child is included in the assessment.

Child↗
PubMed1988

Purification and partial amino acid sequencing of alkaline phosphatase from rachitic rat epiphyseal cartilage.

1. Alkaline phosphatase of rachitic epiphyseal cartilage was purified to apparent homogeneity by sequential application of monoclonal affinity, DEAE-cellulose, and Sepharose CL-6B chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the enzyme showed the presence of a dominant band corresponding to a molecular weight of 80,000. 2. The N-terminal amino acid sequence was determined as follows: Phe-Val-Pro-Glu-Lys5-Glu-Lys-Asp-Pro-Ser10-Tyr-Trp-Arg-Gln-+ ++Gln15-Ala-Gln-Glu- Thr-Leu20-Lys-Asn-Ala-Leu-Lys25-Leu-Gln-Lys-?-Asn-Val-Asn-?- Ala-Lys35-?-Ile-?- Met-Phe40-Leu-(Gly?)-Asp-(Ala/Gly?)-Met45-?-Val-?- (Val/Gly?).

Alkaline Phosphatase↗
PubMed1988

Hepatitis B vaccines in patients with chronic renal failure before dialysis.

Hepatitis B remains a significant risk to patients receiving chronic hemodialysis, but no certain method of prevention has been identified. We tested two vaccines, plasma-derived vaccine (40-micrograms dose) and recombinant-derived vaccine (40-micrograms and 20-micrograms doses), in 61 patients with chronic renal failure who were not yet dependent on dialysis. Patients were followed up clinically and with laboratory tests of kidney function and hepatitis B virus serology for one year. Significantly more recipients of plasma-derived vaccine responded to vaccination; they also achieved a higher titer of antibody to hepatitis B virus than did recipients of recombinant-derived vaccine when evaluated at 6, 7, 9, and 12 mo after vaccination. No serious side effects were observed with any vaccine preparation, nor were excessive adverse effects observed in any group. Compared with the dialysis patients previously studied, patients with renal failure who were not yet dependent on dialysis responded more favorably to the hepatitis B virus vaccine.

Adult↗
PubMed1988

Protein kinase activities in the parathyroid gland: proparathyroid hormone, parathyroid hormone and secretory protein-I as substrates for phosphorylation.

We have identified two protein kinase activities in homogenates of bovine parathyroid tissue following fractionation on DEAE columns. One of these is a protein kinase C based upon its requirement for calcium and phosphatidylserine and the other one is probably M kinase. The protein kinase C phosphorylated both proparathyroid hormone and parathyroid hormone but not secretory protein-I (SP-I). Neither N [1-34] or C [35-84] terminal hormonal fragments were phosphorylated, suggesting that the structure of the intact PTH molecule is required for recognition by the enzyme. A second kinase activity behaving like M kinase was also obtained. This activity, which was not separable from a cAMP dependent kinase, was maximal with only 50 mM MgCl2 as cofactor. SP-I was readily phosphorylated by this activity but parathyroid hormone was not.

Animals↗
PubMed1987

Purification and partial amino acid sequencing of rat bone tumor (UMR106) alkaline phosphatase.

Cultured rat osteosarcoma (UMR106) alkaline phosphatase was purified to apparent homogeneity by sequential application of polyclonal antibody affinity, DEAE-cellulose, and Sepharose CL-6B chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the enzyme preparation treated with sodium dodecyl sulfate and mercaptoethanol showed the presence of a dominant band (using silver staining) corresponding to a molecular weight of 80,000. The amino acid composition was similar to those of various alkaline phosphatases. The N-terminal amino acid sequence was determined as follows: Phe-Val-Pro-Glu-Lys-Glu-Lys- Asp-Pro-Ser-Tyr-Trp-Arg-Gln-Gln-Ala-Gln-Glu-Thr-Leu- Lys-Asn-Ala-Leu-Lys-?-Gln-Lys-?-Asn-Val-Asn-Ala-Lys.

Alkaline Phosphatase↗
PubMed1987

Localization of the Goodpasture epitope to a novel chain of basement membrane collagen.

The chain origins of subunits M1, M2*, and M3 previously described (Butkowski, R. L., Wieslander, J., Wisdom, B.J., Barr, J.F., Noelken, M.E., and Hudson, B.G. (1985) J. Biol. Chem. 260, 3739-3747) of the globular domain of basement membrane collagen were identified, by amino-terminal amino acid sequence analysis, with respect to their relationship to the chains of collagen IV. M1 comprises two polypeptides which correspond to the noncollagenous segments (NC1) of the alpha 1 ad alpha 2 chains of collagen IV. M2*, containing the Goodpasture epitope, and M3 are distinct from these two constituents and from each other but have Gly-X-Y triplets and hydroxyproline at their amino terminus, reflecting the fact that each has a collagen chain origin. These results indicate the presence of two new collagen chains in basement membrane. These new chains appear to be integral components of collagen IV molecules. Alternatively, they could represent new molecular species of basement membrane collagen containing a globular domain, comprising M2* and M3, with physicochemical properties very similar to those of collagen IV.

Amino Acid Sequence↗
PubMed1987

Purification and partial amino acid sequencing of bovine kidney alkaline phosphatase.

Bovine kidney alkaline phosphatase (ALPase) was purified by the sequential application of monoclonal anti-bovine cartilage ALPase affinity, DEAE-cellulose, and Sepharose CL-6B chromatography. Sodium dodecyl sulfate-polyacrylamide-gel electrophoresis showed the presence of a single band corresponding to a molecular weight of 80,000. The N-terminal amino acid sequence of bovine kidney alkaline phosphatase was determined as follows: Leu-Val-Pro-Glu-Lys-Asp-Pro-?-Tyr-Trp-Arg-Asp-Gln-Ala-Gln.

Alkaline Phosphatase↗