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Biomedical subjects

J W Hamilton

Publications and source records attributed to J W Hamilton.

At least 145 records · Page 8Linked to original sources
PubMed1980

Peritoneal dialysis in the treatment of severe hypercalcemia.

A 56-year-old man with multiple myeloma and compromised renal function underwent peritoneal dialysis for the treatment of severe hypercalcemia. During dialysis, peritoneal clearances of total calcium, unbound calcium, urea, and creatinine were assessed. Clearances of total calcium (4.8 +/- 0.4 ml/min) and unbound calcium (7.8 +/- 0.5 ml/min) were shown to vary directly with the clearances of urea (15.5 +/- 1.3 ml/min) and creatinine (8.5 +/- 0.8 ml/min). Despite relatively low clearances of all these solutes, during the period of 42 hours, 1,638 mg of calcium was removed in the dialysate and total serum calcium decreased from 17.6 mg/dl to 10.2 mg/dl. Our data indicates that peritoneal dialysis is an effective adjunct in controlling severe hypercalcemia and should be considered when other forms of therapy are inadequate.

Acute Disease↗
PubMed1979

Resolution of the charge forms and amino acid sequence and location of a tryptic glycopeptide in rat alpha-lactalbumin.

Three charge forms of rat alpha-lactalbumin were separated by ion exchange chromatography on DEAE-cellulose. The amino acid composition of each form was similar but they differed in carbohydrate composition. Each form contained a tryptic glycopeptide having a common polypeptide and heteropolysaccharide unit. The tryptic glycopeptide was sequenced and positioned in rat alpha-lactalbumin, which was partially sequenced from residues 1 to 50. The carbohydrate attachment site was at Asn45. Secondary structure calculations predicted that Asn45 is in a beta bend conformation whereas Asn45 in bovine alpha-lactalbumin, a poorly glycosylated protein, is not in a bend conformation.

Amino Acid Sequence↗
PubMed1979

Structure of the tryptic glycopeptide isolated from rabbit transferrin.

The structure of the tryptic glycopeptide isolated from rabbit transferrin was elucidated by use of sequential Edman degradations, specific exoglycosidases, endo-beta-N-acetylglucosaminidases, methylation analyses, and periodate oxidation studies. The glycopeptide consists of a heteropolysaccharide, AcNeualpha2 leads to 6Galbeta1 leads to 4GlcNAcbeta1 leads to 2Manalpha1 leads to 3[AcNeualpha2 leads to 6Galbeta1 leads to 4GlcNAcbeta1 leads to 2Manalpha1 leads to 6]-Manbeta1 leads to 4GlcNAcbeta1 leads to 4GlcNAc, attached to a peptide, Asn-Ser-Ser-Leu-Cys, via a linkage involving N-acetyl-glucosamine and asparagine. The stoichiometry of this glycopeptide is 2 mol/mol of protein, indicating that rabbit transferrin contains two structurally identical glycopeptide segments.

Amino Acids↗
PubMed1979

Isolation and characterization of porcine parathyroid cathepsin B.

Cathepsin B was isolated from porcine parathyroid tissue and from liver by a procedure involving acetone precipitation, gel filtration, and carboxymethylcellulose chromatography. The final preparations of each migrated as single bands upon sodium dodecyl sulfate polyacrylamide gels but exhibited several minor active variants upon isoelectric focusing. The parathyroid and liver enzymes were similar to each other and also resembled cathepsin B from other sources. The molecular weights for the porcine enzymes were estimated as 25,000, and the isoelectric point was at pH 4.8. The parathyroid enzyme cleaved benzyloxycarbonyl-Val-Lys-Lys-Arg-(4-methoxy)-2-naphthylamide at pH 5.8 and 37 degrees C with a Km of 0.14 mM and a kcat of 68 s-1. The pH optimum for this reaction was pH 6 to 7. The enzyme was unstable above pH 7.5 and below pH 4.5. It was strongly inhibited by HgCl2, ZnSO4, iodoacetate, iodoacetamide, and N-ethylmaleimide which indicated that it is a thiol protease, and by leupeptin, a strong inhibitor of cathepsin B from other sources. Antibodies to the parathyroid enzyme were elicited in rabbits. The antisera formed single precipitin bands upon double diffusion in agar gels against both the parathyroid and liver enzymes. Precipitin bands were formed at both pH 6 and pH 8.5 which indicated that the antisera recognized both native and denatured forms of the enzymes.

Amino Acids↗
PubMed1979

The degradation of proparathormone and parathormone by parathyroid and liver cathepsin B.

Purified cathepsin B from porcine parathyroid glands was allowed to act upon radioactive bovine parathormone and proparathormone at various ratios of enzyme to substrate and for different times. The reaction products were isolated by ion exchange chromatography and analyzed by gel electrophoresis, amino acid composition, sequence analysis, and bioassay. The enzyme cleaved parathormone between residues 36 and 37 yielding a major carboxyl and amino fragment and appeared to cleave proparathormone at the same locus. The amino fragments were degraded further by removal of small peptides (possibly, di- or tripeptides) from their COOH termini. In contrast there was little if any degradation of the carboxyl fragment (residues 37 to 84). Despite the ease with which the enzyme cleaved the arginyl bond in the synthetic substrate benzyloxycarbonyl-Val-Lys-Lys-Arg-(4-methoxy)-2-naphthylamide, it did not remove the near homologous NH2-terminal hexapeptide extension of proparathormone (Lys-Ser-Val-Lys-Lys-Arg-R)--a reaction that would lead to the formation of parathormone from proparathormone. Purified liver cathepsin B cleaved the hormonal substrates in a fashion identical with that of the parathyroid enzyme.

Amino Acid Sequence↗
PubMed1979

Multiple group rape: psychosocial considerations.

Psychiatric examination of the participants in repeated episodes of rape demonstrated that sexual assault combined with stealing represents symbolically an attack upon the bad mother, such hostile acting out enabling the individual to defend against strong, but ambivalent, wishes to be nurtured. Separation from home in each case was considered a crucial precipitant of such behavior. It is suggested that exhibitionistic-voyeuristic conflict may be an important determinant of whether or not rape is committed in group fashion.

Acting Out↗
PubMed1978

The mode of conversion of proparathormone to parathormone by a particulate converting enzymic activity of the parathyroid gland.

The cleavage products from the conversion of proparathormone to parathormone by a bovine and porcine parathyroid microsomal converting activity have been analyzed. In the conversion reaction, the first 6 amino acid residues of the prohormone (Lys-Ser-Val-Lys-Lys-Arg-) are released as an intact hexapeptide. This is rapidly converted to a pentapeptide by removal of the NH2-terminal lysine and then to a tetrapeptide by removal of the COOH-terminal arginine. In order to test for the presence of a postulated COOH-terminal extension of the parathormone sequence in proparathormone, mixtures of 14C-proparathormone and 3H-parathormone were subjected to digestion by trypsin or Staphylococcus aureus protease. The resulting radioactive peptides from the hormone and its precursor were compared. There was no evidence that any fragments different from those from the hormone were released from the prohormone except those accounted for by the NH2-terminal hexapeptide adduct on proparathormone. Thus, the conversion of the prohormone to the hormone catalyzed by the microsomal membrane activity requires only the cleavage of this hexapeptide.

Amino Acid Sequence↗
PubMed1977

The evolution of a shoe fetish.

This paper deals with clinical material gathered from the long-term, psychoanalytically-oriented treatment of a patient with a shoe fetish. Genetic and dynamic aspects of this problem are emphasized. The combination of a dominating mother and a passive and absent father, the sharing of a bed with an older sister until age eleven, and the receipt of frequent enemas contributed directly to the development of the fetish, the most crucial determinant being the commulative traumatic effect of the enemas. During adolescence, the patient also resorted to transvestism to deal with the intensification of castration fears. Becoming a husband and father threatened to disrupt his tenuous defenses and forced him to seek therapy for two years, during which he was able to gain sufficient insight to forego the fetish and to engage in heterosexual activity in reasonably conflict-free manner. Previous theorectical contributions on the subject are included and theorectical issues are dealt with, particularly the role of the core fantasy of the phallic woman in the perversions.

Adult↗
PubMed1976

Newer aspects of parathyroid chemistry and physiology.

We have attempted to integrate in this review many recent studies on the formation, packaging and secretion of parathormone by the parathyroid gland. We have shown that substantial new insights have been gained into this complex cellular operation. Continuing investigation should clarify many of the outstanding questions regarding function of the parathyroid in their central role in calcium homeostasis.

Amino Acid Sequence↗