Activity-induced thermogenesis in lean and genetically obese (ob/ob) mice

Motor activity was approximately 60% lower in genetically obese than in lean mice, during three consecutive hours at thermal neutrality. It is suggested that this must have contributed to the lower heat production measured in the obese mice and that activity-induced thermogenesis contributes significantly to differences in energy expenditure between the genotypes, at least in the short-term.     

Increase in pituitary melanocyte-stimulating hormone activity of genetically obese (ob/ob) mice

Summary Melanocyte-stimulating hormone (MSH) activity was measured in the pituitaries of genetically obese and lean control mice using the frog skin bioassay. Obese mice pituitaries demonstrated very significantly elevated levels of biologically active MSH when compared to their lean littermates. These results support the hypothesis that the elevated levels of pituitary hormones found in obese mice possess true biological activity.     

Altered brain cholinergic enzymes activity in the genetically obese rat

Summary Genetically obese male Zucker rats (fa/fa) and their lean littermates (Fa/-) were used in this experiment. Fourteen-week-old obese and lean littermates were sacrificed and choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) enzymes were assayed in specific brain regions. The assays of these enzymes indicate that obese animals and a significantly lower ChAT activity in the cerebellum, pons, and cerebral cortex and a significant increase in ChAT activity in the thalamus and hypothalamus. Meanwhile, the cerebral cortex, cerebellum, midbrain, thalamus and hypothalamus of the obese animals showed significantly higher AChE activity than their lean littermates. It was concluded from this study that obesity may be associated with changes in the enzymes of the brain cholinergic system.This work was supported by a grant from the National Aeronautics and Space Administration (NAG 2-411), a grant from the National Institutes of Health (NIH RR 0811), and a grant from the Division of Research Resources, National Institutes of Health (NIH Grant RR 03020).     

Dissociation of obesity,hypercholesterolemia and diabetes from atherosclerosis in ob/ob mice

Summary Genetically obese, diabetic and hypercholesterolemic C57BL/6J-ob/ob mice were placed on Purina Laboratory Chow containing 2% cholesterol for up to 4 months. They developed higher plasma cholesterol levels and accumulated an increased quantity of cholesterol in the liver but failed to develop atherosclerotic lesions in the aorta as would be expected in an obese, diabetic and hypercholesterolemic human adult.Acknowledgments. We wish to thank Mr. Willis M. Overton for his excellent technical assistance.     

Colony promoting activity and its target 'pre-CFUc' in genetically anemic mice of W/Wv genotype

Incubation of bone marrow cells with supernatant from long-term cultures of bone marrow cells increases the number of granulocyte-macrophage progenitor cells. This study reveals the presence of target cells of the colony promoting activity (CPA) in W/Wv mouse marrow. It is also shown that CPA does not stimulate erythroid colony formation in vitro.     

Mast cells in the pinna of Balb/c 'nude' (nu/nu) and heterozygotes (ny/+)mice.

The relative number of mast cells in the ear lobes' skin (pinna) of nude (athymic) nu/nu and normal (thymic) nu/+ heterozygotes of Balb/c mice was similar. The results obtained contradict some suggestions about the general influence of the thymus on the number of mast cells in the skin and suggest the existence of some local factor(s) in regulation of skin mast cell numbers.     

Mast cells in the pinna of Balb/c ‘nude’ (nu/nu) and heterozygotes (nu/+) mice

Summary The relative number of mast cells in the ear lobes' skin (pinna) of nude (athymic) nu/nu and normal (thymic) nu/+ heterozygotes of Balb/c mice was similar. The results obtained contradict some suggestions about the general influence of the thymus on the number of mast cells in the skin and suggest the existence of some local factor(s) in regulation of skin mast cell numbers.This work was supported by grant No. CA16426.The author wishes to thank Dr Kenneth Morrison for supplying the mice and the discussion, Mr Duffy Michowski for taking care of the animals used, Mr Carl Polley for taking the pictures and Dr N. R. Rose for the discussion.     

Dystrophic mutation (dy2J) affecting regulation of lactate dehydrogenase (LDH) and pyruvate kinase (PK) in C57BL/6J mice

Summary The genotype difference (dystrophic vs nondystrophic) in the LDH isozymes is observed in kidney. These differences are evident only at birth and at early developmental stages (before the expression of dystrophic symptoms). The tissue specific genotype differences for PK are limited to the thigh muscle (M form) and heart (L form), after the onset of the condition. These differences may reflect the pleiotropic effect of the dy^2J locus during the temporal regulation of these and other enzymes implicated in muscular dystrophy (MD).This research was financed by a Natural Sciences and Engineering Research Council Canada grant to S.M.S.     

Lipolytic response of ‘diabetic’ mice (db/db) to isoproterenol and propranolol in vivo

Summary The genetically diabetic and obesedb/db mice responded lipolytically to isoproterenol and propranolol similarly to normal mice in vivo. However, considering the large amount of triglyceride in adb/db mouse, we conclude that the in vivo response ofdb/db adipose tissue is deficient in magnitude.     

Gonadectomy and growth ofTaenia crassiceps (Cestoda) cysticerci in mice

Summary Gonadectomy of SWR of both sexes significantly reduced the number of cysticerci ofTaenia crassiceps, 60 days post infection. There was a significant decrease in the total number of larvae and the number of nonbudding individuals, corresponding with increased number of budding larvae. This indicates that the asexual multiplication of cysticerci in populations from gonadectomized mice was inhibited.     

Delayed hypersensitivity in BALB/c and Charles-River mice injected at birth with a single dose of 7,12-dimethylbenz (α) anthracene (DMBA)

Riassunto Una iniezione neonatale di 100 g di DMBA in topi BALB/c e Charles-River deprime la risposta immunitaria, a tipo ipersensibilità ritardata, in animali di 90–100 giorni di età, mentre non pare agire come fattore deprimente in topi valutati 20–30 giorni dopo la nascita ed il trattamento oncogeno.     

Gonadectomy and survival ofAncylostoma caninum (Nematoda) filariform larvae in mice

Summary Gonadectomy reversed the susceptibility response of male and female Swiss mice toAncylostoma caninum infection. Orchiectomy decreased the survival of filariform larvae (p>0.001 to <0.25), whereas ovariectomy increased it significantly (p>0.001 to <0.01).We wish to acknowledge our gratitude to the late Professor H. Swarup for valuable suggestions, to Professor G.N. Johri for laboratory facilities, and to the University Grants Commission, New Delhi, for financial support in the form of a Junior Research Fellowship to I. B.     

Gonadectomy and growth of Taenia crassiceps (Cestoda) cysticerci in mice.

Gonadectomy of SWR of both sexes significantly reduced the number of cysticerci of Taenia crassiceps, 60 days post infection. There was a significant decrease in the total number of larvae and the number of nonbudding individuals, corresponding with increased number of budding larvae. This indicates that the asexual multiplication of cysticerci in populations from gonadectomized mice was inhibited.     

A study of granulated metrial gland cell differentiation in pregnant,macrophage-deficient,osteopetrotic (op/op) mice

A population of uterine natural killer (NK) cells, commonly called granulated metrial gland (GMG) cells, differentiates in the mouse uterus during normal pregnancy. Little is known regarding the process of differentiation of GMG cells or of other NK cell subsets. It has been suggested that macrophage precursors, under the combined influences of the cytokine growth factors colony stimulating factor-1 (CSF-1) and interleukin-2, become NK-cell like in morphology, pattern of target cell lysis and surface antigen phenotype. Mice expressing the mutation osteopetrosis (op/op) are unable to produce the cytokine CSF-1. To determine whether CSF-1 is required for the successful differentiation of uterine NK cells, implantation sites in pregnant,op/op mice were studied histologically. GMG cell differentiation appeared to progress normally inop/op mice studied between days 7 and 14 of gestation. Thus, the growth factor CSF-1 is not required for differentiation of the uterine NK cell subset known as GMG cells and probably GMG cells do not differentiate from macrophage precursor cells which are deficient inop/op mice.     

Multiplication of human-derivedPneumocystis carinii in severe combined immunodeficient (SCID) mice

clinically healthy SCID mice were infected intratracheally withPneumocystis carinii (PC) of human origin. The data obtained provides unambiguous evidence that progressive multiplication of PC organisms of human origin takes place in the lungs of experimentally infected animals. SCID mice that were infected with human-derived PC also revealed a markedly greater number of mouse PC organisms in their lungs than the controls. All the SCID recipients of human PC died by day 65 post infection, whereas the controls, housed under identical conditions, started dying significantly later due to severe mouse pneumocystosis. This animal model could be used for the maintenance and propagation of human PC, and for evaluating strategies for treating human pneumocystosis.     

Encephalomyocarditis (EMC) virus-induced diabetes mellitus prevented byCorynebacterium parvum in mice

Summary Corynebacterium parvum prevented the development of encephalomyocarditis virus-induced diabetes in mice, when it was given 3–14 days before the virus infection. This treatment inhibited virus replication in the pancreas of the infected mice at an early stage of the infection.     

Reduced collagen biosynthesis in oral mucosa of beige (Chediak-Higashi) mice

Summary Oral mucosa of beige (Chediak-Higashi) mice had decreased levels of collagen synthesis and prolyl hydroxylase activity compared with normal animals. No significant difference was observed in non-collagen protein synthesis between the two groups. These results suggest that decreased collagen biosynthesis in oral tissues may be partially involved in the increased incidence of periodontal disease in the Chediak-Higashi syndrome.