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Biomedical subjects

J W Jacobs

Publications and source records attributed to J W Jacobs.

At least 145 records · Page 8Linked to original sources
PubMed1982

The effect of divorce on fathers: an overview of the literature.

Divorce is becoming a major mental health problem in the United States. With rare exception psychological attention has usually focused on the effect of divorce on children and mothers. The author suggests that as some fathers become more involved in family nurturing they will be more intensely affected by marital disruption, particularly as it involves changes in the relationship to their children. A review of the recent psychological literature on divorce and custody is presented as a framework for understanding the divorcing father who is requesting psychiatric help.

Adult↗
PubMed1982

Isolation and partial sequence analysis of rat basic somatomedin.

Rat basic somatomedin (Sm) was prepared with an improved purification scheme from the pooled sera of Wistar Furth rats previously inoculated with cells from the pituitary tumor MStT/W15. Amicon hollow fiber diafiltration facilitated the processing of large batches of serum, eliminating the necessity of running smaller portions of material on gel filtration columns to achieve the same qualitative separation. The yield from this technique was excellent. Basic rat Sm was separated from a C3ades Arg component of complement by a narrow pH range isoelectric focusing step. Subsequent chromatography on carboxymethyl-cellulose and Sephadex resins was very efficient, providing a 100-fold purification, with a recovery of Sm activity of approximately 65%. The final product was judged to be pure by a variety of criteria. Structural analysis of this material has demonstrated that the amino-terminal sequences of rat basic Sm and human insulin-like growth factor I are strikingly similar, confirming the homology proposed earlier on the basis of receptor cross-reactivity.

Amino Acid Sequence↗
PubMed1982

Absence of detectable calcitonin synthesis in the pituitary using cloned complementary deoxyribonucleic acid probes.

Recently, several investigators have detected calcitonin (CT)-like material in pituitary tissues by immunochemical techniques. In the present study we examined CT biosynthesis in rat pituitaries using specific and sensitive hybridization assays which used a cloned CT complementary DNA (cDNA) to detect CT mRNAs. Rat CT cDNA encoding the entire CT precursor, was radiolabeled to a high specific activity with 32P-labeled nucleotide and hybridized with mRNA extracted from pituitaries of both normal and genetically obese Zucker rats, in which elevated levels of immunoreactive CT-like material have been detected. Using these assays, we failed to detect mRNA with size and hybridization characteristics similar to those of thryoidal CT mRNA in either normal or Zucker rat pituitaries. We conclude that a mRNA homologous in sequence to that encoding rat thyroidal CT is not synthesized in the pituitary gland. In previous immunochemical studies a CT-like peptide may have been detected which is synthesized in the pituitary but lacks sufficient structural homology for the mRNA to react with our cDNA probe to thyroidal CT mRNA. Alternatively, in these prior studies thyroidal CT bound to pituitary receptors may have been detected.

Animals↗
PubMed1981

Calcitonin messenger RNA encodes multiple polypeptides in a single precursor.

Recombinant DNA techniques were used to analyze the structure of the messenger RNA encoding a precursor of calcitonin, a small calcium-regulating hormone of 32 amino acids. Analyses of the nucleotide sequences of cloned complementary DNA's comprising the entire coding sequence of the messenger RNA revealed that calcitonin is flanked at both its amino and carboxyl termini by peptide extensions linked to the hormone by short sequences of basic amino acids. The location of glycine next to the carboxyl terminal prolinamide of calcitonin is consistent with indications that glycine is required for the enzymatic amidation of proline to the prolinamide. During cellular biosynthesis, calcitonin arises from a large precursor protein by cleavages at both amino and carboxyl terminal residues of the hormone. These findings raise questions concerning the regulation of these cleavages and the potential biological functions of the precursor extensions derived from these cleavages.

Amino Acid Sequence↗
PubMed1981

Procalcitonin is a glycoprotein.

Messenger RNA extracted from rat medullary carcinoma of the thyroid directs the synthesis in cell-free translation systems of a precursor of calcitonin, Mr = 15,000, substantially larger than the mature form of the hormone, Mr = 3,500. When translations of the mRNA were carried out in the presence of microsomal membranes prepared from a canine pancreas, a larger product (apparent Mr = 17,000) was observed by electrophoresis of the labeled proteins in the translation mixtures on sodium dodecyl sulfate-polyacrylamide gels. This membrane-processed product of Mr = 17,000 was specifically immunoprecipitated by an antiserum to synthetic calcitonin and bound to concanavalin A-Sepharose. Incubation of the proteins synthesized in the cell-free translations performed in the presence of microsomal membranes with the glycosidase, endo-beta-N-acetylglucosaminidase H, reduced the apparent molecular weight of the membrane-processed precursor from 17,000 to 12,000. In addition, the processed Mr = 17,000 calcitonin-related precursor, but not the initial, unprocessed precursor of Mr = 15,000, was resistant to proteolytic digestion by a mixture of trypsin and chymotrypsin. These results indicate that the biosynthesis of calcitonin involves the glycosylation and proteolytic cleavage of a newly synthesized precursor along with sequestration of the processed precursor within microsomal vesicles. Thus, the calcitonin precursor undergoes extensive co- and post-translational processing to the smaller, unglycosylated hormone that is secreted.

Animals↗
PubMed1981

Medullary thyroid carcinoma identified by cell-free translation of tumor messenger ribonucleic acid in a patient with a neck mass and the syndrome of ectopic adrenocorticotropin.

We report a patient who presented with a lateral neck mass and Cushing's syndrome secondary to the ectopic production of ACTH. The initial diagnosis was a nonchromaffin paraganglioma based on conventional light and electron microscopic studies. However, during this patient's hospital course, we determined that mRNA extracted from the tumor directed the translation of a calcitonin precursor in a cell-free system. This finding led to a consideration of the diagnosis of medullary thyroid carcinoma, which was then confirmed by further endocrine and histological evaluations. This is a report of the identification of a tumor type using techniques of molecular biology.

ACTH Syndrome, Ectopic↗
PubMed1980

Nucleotide sequence of a cloned structural gene coding for a precursor of pancreatic somatostatin.

We have constructed and cloned, in bacteria, recombinant plasmids containing DNA complementary to mRNA coding for a pancreatic pre-prosomatostatin, a product of the cell-free translation of pancreatic islet mRNAs shown previously by immunoprecipitation to be a precursor of somatostatin. A clone containing a nearly full-length cDNA insert of 550 base pairs was identified and appeared to contain the entire coding sequence for the somatostatin precursor in addition to portions of the 5' and 3' untranslated regions. mRNA coding for the pre-prosomatostatin is 600-630 bases long as determined by agarose gel electrophoresis and hybridization with labeled cDNA. Analyses of the nucleotide sequence of the cDNA revealed a protein of 119 amino acid beginning with methionine followed by a typical leader sequence containing 18 hydrophobic amino acids. The tetradecapeptide somatostatin, identical in sequence to mammalian hypothalamic somatostatin, is located at the carboxy terminus followed immediately by a stop codon. An ARg-Lys sequence immediately preceding the sequence of somatostatin is typical of a prohormone cleavage site. A sequence Ala-Pro-Arg-Glu preceding the Arg-Lys cleavage site is identical to that found in porcine prosomatostatin. The evolutionary conservation of the identical amino acid sequence of the somatostatin tetradecapeptide from fish to mammals is remarkable. In addition, similar conservation, in fish and mammals, of the sequence Ala-Pro-Arg-Glu-Arg-Lys preceding the coding region for somatostatin suggets that this particular sequence may have biologic importance in cellular processing of the somatostatin precursor.

Amino Acid Sequence↗
PubMed1980

Glucagon precursors identified by immunoprecipitation of products of cell-free translation of messenger RNA.

Polyadenylated RNA extracted from anglerfish islets was translated in a wheat germ cell-free system containing [35S]methionine in the presence and absence of microsomal membranes prepared from a canine pancreas. Labeled translation products were analyzed by immunoprecipitation with an antiserum to porcine glucagon, followed by electrophoresis of the translation products and immunoprecipitated proteins on SDS polyacrylamide gels. In the absence of microsomal membranes two proteins of Mr = 14,500 and Mr = 12,500 were specifically immunoprecipitated with antiglucagon serum. Addition of microsomal membranes to the translation reactions resulted in a diminution of the labeled protein of Mr = 14,500 and a marked increase in the immunoreactive protein of Mr = 12,500. The protein of Mr = 12,500 was resistant to degradation by proteolytic enzymes added to translation reactions, indicating that it was segregated within microsomal vesicles. These results are consistent with synthesis of anglerfish islet glucagon in the form of a pre-prohormonal precursor (Mr = 14,500) containing a leader sequence that is cotranslationally cleaved from the protein by enzymes associated with microsomal membranes to produce a smaller intermediate prohormonal precursor (Mr = 12,500) of pancreatic glucagon (Mr = 3500).

Animals↗
PubMed1979

Detection of cognitive deficits by a brief mental status examination: the Cognitive Capacity Screening Examination, a reappraisal and a review.

Results of a brief mental status questionnaire, the Cognitive Capacity Screening Examination (CCSE), were compared with the clinical evaluations of 59 patients on a neurology service. In 71% of the cases, the CCSE scores correctly indicated a cognitive deficit (true-positive) or the absence of one (true-negative); false-negative results were observed in 15% and questionable negative results were found in 10%. Abnormal neurologic physical signs were present in 90% of all patients with cognitive deficits. In this population, although positive CCSE scores were reliable, negative scores were often misleading. Mild diffuse intellectual dysfunction (dementia) and some discrete intellectual deficits (aphasia and anosognosia) went undetected. Cognitive deficits associated with major cerebral disease were unappreciated in nine patients. Caution is recommended in interpreting negative CCSE scores. Abbreviated screening devices are only a preliminary approach to mental status evaluation; this test requires further refinement.

Aged↗
PubMed1978

Purification, characterization, and amino acid sequence of rat anaphylatoxin (C3a).

C3a anaphylatoxin derived from the third component of complement has been isolated from rat serum and its complete amino acid seuqence determined. A three-step purification procedure was employed that consisted of gel filtration on Sephadex G-100, followed by chromatography of the anaphylatoxin-containing pool on carboxymethylcellulose. A subsequent separation on DEAE-Sephadex resolved C3a from minor contaminating peptides. Biological studies have shown that purified rat anaphylatoxin is approximately twice as active as human or porcine C3a when tested for smooth-muscle contraction. In addition to the active form of rat anaphylatoxin, a serum carboxypeptidase B inactivated form of C3a (C3ades-Arg) was purified from rat serum and utilized in subsequent structural studies. Sequence analysis of rat C3a was facilitated by a long automated Edman degradation which established the first 55 residues of the anaphylatoxin. Overlapping peptides were generated by cyanogen bromide and trypsin, and the resultant fragments were sequenced by either automated or manual Edman procedures. The primary structure of rat C3a is 70% identical to the previously determined structures of human and porcine anaphylatoxin. Antisera raised to the purified rat peptide do not cross-react immunologically by Ouchterlony analysis with either human or porcine C3a.

Amino Acid Sequence↗