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Biomedical subjects

C L McLaughlin

Publications and source records attributed to C L McLaughlin.

At least 73 records · Page 4Linked to original sources
PubMed1979

Cholecystokinin, amphetamine and diazepam and feeding in lean and obese Zucker rats.

The hyperphagia characteristic of some types of obesity may result from a deficiency in one or more components of the systems controlling satiety which in rats may include the gastrointestinal hormone cholecystokinin (CCK). Obesity may also influence responsivity to often used central nervous system (CNS)-acting drugs and combination of drugs. In these experiments it was shown that: (1) Zucker fatty rats were less sensitive than lean to intraperitoneal injections of 20 U/kg CCK after a 6-hr fast and when reduced were less sensitive than lean and less sensitive than when obese to injections of 5 U/kg CCK; (2) Although fatties were equally sensitive as leans to injections of 0.5 and 1.0 mg/kg d-amphetamine sulfate, when reduced, they were less sensitive; (3) Injections of 1.25 and 2.5 mg/kg diazepam produced smaller increases in food intake after a 6-hr fast in fatty and reduced fatty than lean rats; (4) Combination of diazepam with cholecystokinin in both fatty and lean rats produced feeding similar to that following injection of carrier; and (5) A similar additive effect was obtained in both fatty and lean rats when diazepam was combined with amphetamine; however, the fatty appeared to be more sensitive to the amphetamine than the diazepam effect. Thus the Zucker fatty rat appears to be less sensitive to these chemicals which affect food intake, which supports the contention that their CNS is generally less responsive.

Animals↗
PubMed1978

Antigenic cross-reactivity between human and marmoset zonase pellucidae, a potential target for immunocontraception.

Cross-reactivity between marmoset, chimpanzee, human and pig zona pellucida antigens was demonstrated by immunofluorescence and zona precipitation. In marmosets, anti-zona antibody prevented sperm attachment to eggs in vitro, and the antibody could be detected on zonae of ovarian oocytes following passive immunization. Use of the marmoset as an animal model in testing feasibility of the zona approach to immunocontraception is discussed.

Animals↗
PubMed1976

Luminescence studies on Bence-Jones proteins and light chains of immunoglobulins and their subunits.

To provide information on the tertiary structure of the antibody molecule we have investigated the luminescent properties of the light polypeptide chain of human immunoglobulins. The fluorescence and phosphorescence yields, spectra, lifetimes, and anisotropies of a large number of homogeneous light chains, i.e., Bence-Jones proteins and light chains derived from myeloma proteins, were measured. No two proteins gave identical tyrosyl or tryptophyl fluorescence spectra in comparative studies on over 75 proteins belonging to the four basic subgroups of kappa chains and of lambda chains. Spectral differences were apparent even among proteins exhibiting more than 85% amino acid sequence identity. The fluorescence yields of tyrosine and tryptophan vaired 10- and 100-fold, respectively; the Stokes' shift of tryptophan ranged from 328 to 365 nm, but that for tyrosine was apparently invariant (305-307nm). Emission as well as excitation spectra showed tyrosyl and tryptophyl redidues interact minimally or not at all. Fluorescence lifetimes of the tyrosyl and tryptophyl contributions were measured spearately, and the apparent natural lifetimes were calculated. Proteins could be grouped in accordance with similarities in fluorescence lifetimes and fluorescence yields; there was no evident relationship between these groupings and the light chain type (kappa or lambda), amino acid sequence, or tryptophan content. Also apparent were individual differences among kappa light chains and among lambda light chains in respect to their tyrosyl and trptophyl phosphorescence spectra and phosphorescence lifetimes. Certain proteins showed an atypical, short-lived tryptophan phosphorescence decay time. Such variance in the luminescent behavior of the tryptophyl residue(s) indicates a conformational interaction between the V and C domains of light chains. Selective proteolytic cleavage of the light chain into VL and CL fragments permitted the comparison to be made of the luminescent properties of the V and C domains with those of the whole protein. The V domain and intact protein have luminescent features in common, whereas the C domain possesses features distinctive from that of the native protein. Data derived from fluorescence anisotropy spectral studies of intact light chains and their VL-related fragments indicate that energy transfer between tryptophyl residues occurs in the C domain. The results of emission spectroscopic measurements performed at 220 and at 77 K indicate that the observed phophorescence of light chains is mainly from a tryptophyl residue contiguous to a disulfide link. The potential for interdomain interaction in light chains is evidenced by the finding that the orientation of the tryptophyl residue(s) in the V domain can influence the tryptophyl-disulfide ling interactions in the C domain; this interaction may account further for the extensive structural diversity of antibody molecules.

Bence Jones Protein↗
PubMed1975

Bence Jones proteins and light chains of immunoglobulins. XI. A transient Bence Jones-related protein associated with corticosteroid therapy.

Urine specimens from patients with multiple myeloma and Bence Jones proteinuria frequently contain low molecular weight proteins which correspond either to the amino-terminal, variant half (VL) or to the carboxyl-terminal, constant half (CL) of the Bence Jones protein. Analyses of urine specimens from such patients who had received high doses of corticosteroids as part of their treatment regimen revealed that concomitantly with a decrease in Bence Jones protein excretion was the appearance of a low molecular weight protein related to the Bence Jones protein but not identical to the VL or to the CL. Analyses of daily urine specimens obtained from one such patient over an extended time period revealed that a reproducible chain of events occurred during a treatment regimen which included oral administration of 75 mg of prednisone daily for 7 consecutive days. The amount of Bence Jones protein excreted decreased progressively, and by the 5th day was usually less than 10% of the pretreatment value. The urine specimen obtained on the 6th day of treatment was virtually devoid of Bence Jones protein but contained a newly appearing protein whose electrophoretic mobility was distinct from that of the Bence Jones protein or its VL or CL. Cessation of corticosteroid therapy resulted in a prompt disappearance of the new protein and in a progressive increase in the amount of Bence Jones protein excreted. The new protein was isolated from the urine of this patient and was purified for comparative studies with Bence Jones protein and with the VL and CL prepared by specific enzymatic cleavage of the Bence Jones protein. These studies revealed that the new protein was most related antigenically to the CL, but could be distinguished immunochemically from the CL. This new protein, a component found in vivo related to the constant half of the light polypeptide chain, was designated CL, and was structurally 25 amino acid residues longer than the CL, that is, the amino-terminus of the enzymatically prepared CL was at position 117 whereas that of the transitory new Bence Jones-related protein was at position 92 of the light polypeptide chain. Biosynthetic studies were performed with plasma cells derived from the bone marrow of this patient at a time when both the CL and the Bence Jones protein were being excreted; both proteins were identified in extracellular culture fluid by immunochemical techniques. Whether the CL is of synthetic or catabolic origin is presently not known; however, the detection of the CL and the absence of any detectable protein related to the VL in the extracellular culture fluid might imply a synthetic origin of the CL and suggest a corticosteroid-induced alteration in light chain synthesis.

Amino Acid Sequence↗
PubMed1975

Feeding following intrahypothalamic injections of calcium and magnesium ions in sheep.

To study ionic effects on hypothalamic control of feeding, seven sheep were each prepared with six bilateral medial-hypothalamic guides. Hypothalamic loci were identified where feeding resulted following 1 mu 1 injections of calcium chloride and/or magnesium chloride. Doses of 1 and 2 mumol were most effective to induce feeding, and potassium chloride was not effective. Injections of phentolamine, LB-46, carbachol, atropine, or prostaglandin E1 did not inhibit the feeding responses following magnesium chloride injections into magnesium ion responsive loci. Feeding following calcium chloride injections into calcium ion responsive loci was blocked by atropine and reduced by phentolamine. Carbachol and prostaglandin E1 elicited feeding when injected into magnesium but not calcium ion responsive loci. Injections of carbachol followed by magnesium chloride resulted in greater feeding than when either chemical was injected alone. Calcium and/or magnesium ion bound feeding loci were in the anterior, ventromedial, dorsomedial, posterior and lateral hypothalamus, and the mammillary bodies. These ions elicited feeding in sheep perhaps by decreasing excitability of feeding-inhibitory neural pathways in the hypothalamus.

Animals↗
PubMed1973

A hidden antigenic site localized to the constrant region of light chains of immunoglobulins.

An antigenic site, which was not immunochemically demonstrable in the intact kappa light polypeptide chain, was exposed by enzymatic cleavage of the kappa chain into its variant half and constant half. This antigenic site located in the constant region the kappa chain was detected immunochemically by several antiserums that had specificity for this site. Treatment of an intact kappa chain with a dissociating agent resulted in the exposure of the hidden antigenic site, which was as readily detected in the unfolded polypeptide chain as in the isolated constant half.

Bence Jones Protein↗