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PubMed2000

Altered intracellular calcium homeostasis in cerebellar granule cells of prion protein-deficient mice.

Previous studies have indicated that recombinant cellular prion protein (PrP(C)), as well as a synthetic peptide of PrP(C), affects intracellular calcium homeostasis. To analyze whether calcium homeostasis in neurons is also affected by a loss of PrP(C), we performed microfluorometric calcium measurements on cultured cerebellar granule cells derived from prion protein-deficient (Prnp(0/0)) mice. The resting concentration of intracellular free calcium [Ca(2+)](i) was found to be slightly, but significantly, reduced in Prnp(0/0) mouse granule cell neurites. Moreover, we observed a highly significant reduction in the [Ca(2+)](i) increase after high potassium depolarization. Pharmacological studies further revealed that the L-type specific blocker nifedipine, which reduces the depolarization-induced [Ca(2+)](i) increase by 66% in wild-type granule cell somas, has no effect on [Ca(2+)](i) in Prnp(0/0) mouse granule cells. Patch-clamp measurements, however, did not reveal a reduced calcium influx through voltage-gated calcium channels in Prnp(0/0) mice. These data clearly indicate that loss of PrP(C) alters the intracellular calcium homeostasis of cultured cerebellar granule cells. There is no evidence, though, that this change is due to a direct alteration of voltage-gated calcium channels.

Animals↗

PubMed1985

Nucleic acid and protein metabolism in undernutrition and protein deficiency.

This review discusses the metabolism of nucleic acids and proteins in various models of undernutrition in female rats and their neonatal and 21-day-old progeny. Based on the observations noted in our laboratories and those of other investigators, it is concluded that body and organ weights as well as various parameters of cellular growth (DNA, RNA, proteins, amino acids and total nucleotides) fail to increase normally in dietary-insulted animals. Protein and RNA synthesis demonstrate variable responses, leading to the speculation that modulation of mRNA metabolism and of protein synthesis occurs in dietary-restricted rats. These findings are also confirmed by the organ weight to DNA ratios. It is further noted that, despite the increases in protein and RNA synthesis in certain organs, protein and RNA register below-normal values, indicating that their degradation is much faster than their formation. This postulate is supported: by the enhanced activities of acid cathepsin (a protein-degrading enzyme) and of RNAse A (a RNA-degrading enzyme); by the elevated concentrations of circulating amino acids and total nucleotides; as well as by the accelerated excretion of nitrogenous compounds in the urine and feces of dietary-restricted animals. Modifications of RNA turnover are also evident in the tRNA and soluble RNA fractions of the liver of dietary-insulted rats. Studies on brain mRNA translatability have revealed: that food deprivation elicits a shorter species of pre-mRNA via a reduced polynucleotide elongation rate; that not all poly A+ RNA sequences present in control rats occur in dietary-restricted animals; and that the translatability of polymerase II is far lower in dietary-insulted rats. Other investigations on the translatability of liver, brain, kidney, spleen and thymus mRNA have demonstrated changes in mRNA via altered protein synthesis in various organs of dietary-restricted rats. Generation studies have shown that adaptation prevails in the first, second and third generation offspring of dietary-insulted rats, after which all parameters decline in fourth and fifth generation offspring. By reducing the litter size and exchanging the pups of control and dietary-restricted rats during the lactation period, partial restoration of the cellular growth of different organs is effected with the exception of the brain, in which damage is irreversible.

Animals↗

PubMed1995

Replacement therapy with a monoclonal antibody purified protein C concentrate in newborns with severe congenital protein C deficiency.

Protein C replacement therapy with a monoclonal antibody purified, virus inactivated protein C concentrate was carried out in nine infants (three male, six female) with severe congenital protein C deficiency and life-threatening purpura fulminans and/or thrombosis associated with disseminated intravascular coagulation (DIC). Eight infants were homozygous for protein C deficiency; one was a compound heterozygote. The treatment period varied from 22 days to three years. The half-life of protein C was found to be as short as two to three hours during activation of the coagulation system, increasing to approximately ten hours after stabilization. During the acute phase, protein C levels of 0.10 to 0.25 IU/mL were associated with elevated markers of coagulation activation indicating DIC, while protein C levels greater than 0.25 were associated with normalization of coagulation markers. No product-related side effects were reported. Episodes of bleeding or purpura recurred in all patients who were switched to oral anticoagulant therapy, necessitating reinstatement of protein C replacement therapy, either as needed to control symptoms, or on a long-term prophylactic schedule, alone or in addition to oral anticoagulation. Home treatment with protein C concentrate allowed a near-normal life-style for patients who otherwise would be hospitalized for long periods of time.

Antibodies, Monoclonal↗

PubMed1982

Disposition of dapsone in protein deficiency--an experimental study in mice.

With an aim to evaluate the metabolic disposition of Dapsone (DDS) in protein malnutrition, a study was undertaken to determine DDS content of blood and tissues of protein deficient mice in comparison to the levels in ad-libitum and pair-fed mice. Three groups of Rockfeller's strain mice of same sex (roughly weighing 25 gm) were fed on low protein diet and high protein diet (for pair-fed and ad-libitum groups). After one month feeding DDS was administered by oral intubation daily for 7 days at a dose of 0.01 mg per g body weight. On 7th day animals were sacrificed 3 hours after DDS administration. Heparinised blood was collected from ocular plexus. Tissues (liver and kidney) were taken out for DDS estimations. DDS levels were determined by the method of Simpson (1949) and tissue protein content was assayed by the method of Lowry et al (1951). Hypoproteinemic mice presented higher values for blood and tissue DDS as compared to their pair-fed and ad-libitum fed groups. Our observations indicate that in hypoproteinemic mice, on account of the possible diminished binding of DDS to plasma albumin, the concentration of free DDS in blood and in tissues is higher.

Animals↗

PubMed1987

Specific effects of weight loss, protein deficiency and energy deprivation on the water and electrolyte composition of young rats.

Specific effects of weight loss, protein deficiency and energy deprivation on the water and electrolyte content of the body were studied. Longitudinal changes in total body Na and Cl were measured by neutron activation analysis in young rats fed either a low protein diet (LP) ad libitum or a control diet in restricted amounts (ER). Total body Ca was determined to monitor growth of skeletal mass. Four balance periods were defined to represent various stages of protein or energy deprivation. The chemical composition of the rats was determined at the end of the study and compared with that of rats killed at the start of the study. Changes in body composition of LP rats were attributable chiefly to wasting of body cell mass. There was no retention of Na and Cl until severe hypoalbuminemia and edema developed after chronic protein deprivation; at this time, Na and Cl were retained in the same proportion as their molar ratio in extracellular fluid (ECF). The resulting increase in ECF volume accounted for the high total body water values in LP rats. Energy restriction to approximately 80% of maintenance requirements for 20 d resulted in Na retention in a compartment distinct from either the Cl or Ca space. With prolonged ER, there was preferential wasting of cell mass and adipose tissue but relative preservation of the ECF compartment; there was no net retention of Na and Cl, and hydration of fat-free mass was normal. The differences in the body compositions of ER and LP rats suggested that protein and energy deprivation can have separate effects on Na and Cl homeostasis that are distinct from changes induced by a loss of cell mass.

Animals↗

PubMedDate not supplied

Experimental protein deficiency in adult rats.

Male adult rats of the Wistar strain were fed "ad libitum" either a protein-free or a 20% casein diet for a period of 28 to 32 days. At the end of the experimental procedure, the animals given the protein-free diet presented a marked loss of body weight plus low levels of plasma protein and albumin concentration. Their livers showed diffuse fatty changes; most of the animals had moderate to severe fatty liver infiltration. They had a negative cumulative nitrogen balance; on the contrary, rats fed the 20% casein diet showed nitrogen retention. The animals of one of the two protein-deficient groups had a significant lower food intake than its control group. However, when food intake was related to animal body weight (g/100 g), the rates of rats on the 20% casein diet and those on protein-free diet were not significantly different.

Animals↗

PubMed2004

Optico-cochleo-dentate degeneration associated with severe peripheral neuropathy and caused by peroxisomal D-bifunctional protein deficiency.

The clinical, neuroradiological, neuropathological and biochemical findings in a patient with optico-cochleo-dentate degeneration (OCDD; OMIM 258700) are presented in a severe case succumbing at the age of 4 years. The electron microscopic and biochemical data showed for the first time that OCDD may occur as the phenotypic expression of D-bifunctional protein deficiency, i.e., a peroxisomal disorder. The boy was born as the first child of healthy, consanguineous parents of Turkish origin. No other family members were affected. The main clinical symptoms consisted of muscle hypotonia ("floppy infant"), generalized epileptic fits, hypacusis, rotatory nystagmus, insufficient pupillary reactions, and mental retardation. Fibroblast cultures revealed D-bifunctional protein deficiency. Neuropathological examination displayed moderate frontoparietal and insular microgyria, and atrophy of the cerebellum. Loss of neurons was severe in the granular layer, the Purkinje cell band of the cerebellum, and rather complete in the dentate nucleus. A corresponding loss of myelinated fibers associated with characteristic periodic acid-Schiff-positive macrophages was most prominent in the white matter of the cerebellum. There was additional severe loss of myelinated fibers in the central portions of the optic nerve, reduction of the nerve fiber density in the cochlear nerve, and reduction of myelinated nerve fibers by about 80-90% in the sural nerve, which has not been studied in previous cases. At the electron microscopic level, characteristic inclusions mainly in perivascular macrophages and astrocytes were the most prominent finding. The inclusions usually showed a bilaminar structure, whereas trilaminar structures, typically seen in adrenoleukodystrophy, and multilaminar structures were less frequently seen.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1991

Maternal protein deficiency in rat: effects on central nervous system gangliosides and their catabolizing enzymes in the offspring.

Maternal protein deficiency imposed on rats a month prior to conception, and during gestation and lactation, resulted in a significant cell loss in cerebrum, cerebellum, brain stem and spinal cord of pups at weaning. The cerebellum was the most affected central nervous system (CNS) region; it contained only 25% of the normal cell number. Undernourished pups were also found to have a lower concentration of total gangliosides in cerebrum as compared to that of controls. However, the total ganglioside concentration was unaffected in the cerebellum, brain stem and spinal cord by maternal undernutrition. In all regions, undernutrition caused significant changes in the proportions of individual gangliosides; these alterations were region-specific. Sialidase, beta-galactosidase, beta-glucosidase, and beta-hexosaminidase, which are involved in the catabolism of gangliosides, showed higher activities in all the regions of undernourished pups, suggesting that these enzymes may play a role in maintaining the porportions of various ganglioside fractions.

Animals↗

PubMedDate not supplied

Influence of dietary restriction and protein deficiency on plasma half-life and tissue distribution of tetracycline in rats.

1. The effects of dietary restriction and protein deficiency on plasma half-life and tissue distribution of tetracycline were studied in rats by feeding either a 20% protein diet in restricted quantity or a 9% protein diet ad lib and compared with rats given a 20% protein diet ad lib (control group). 2. It was observed that half-life of tetracycline was shortened and that plasma and tissue Cmin levels at steady-state were lower in undernourished rats. Tissue concentrations in liver, kidney, muscle and bone correlated well with plasma levels. A high degree of correlation was also observed between plasma and tonsillar concentrations of tetracycline in human subjects. 3. These studies indicate that undernourished subjects may require an altered dosage regimen of tetracycline to maintain effective steady-state concentrations of the drug.

Adolescent↗

PubMed1987

Absence of thrombosis in subjects with heterozygous protein C deficiency.

Protein C deficiency has been thought to be associated with an increased risk of venous thrombosis. To establish a normal range of values, we used a two-site monoclonal-antibody assay to measure protein C levels in 699 healthy adults. The distribution was log normal; 95 percent of the values ranged from 70 to 140 percent of the overall mean (4.03 micrograms per milliliter). Two subjects had levels more than 3.5 SD below the mean (34 and 50 percent), consistent with heterozygous deficiency. We also screened 4723 other blood donors and found 8 additional unrelated subjects with levels from 33 to 51 percent of normal. Autosomal inheritance of heterozygous protein C deficiency was confirmed in them by a detailed study of four families. Levels from 55 to 65 percent of normal are consistent with either heterozygous deficiency or the lower end of the distribution of normal values, and were found in 79 of 5422 subjects when the two groups were combined. None of the subjects had any history of venous thrombosis. We conclude that heterozygous deficiency of protein C has a prevalence of 1 in 200 to 300, a figure consistent with the known number of homozygous infants recently identified, and that levels consistent with heterozygous deficiency are found in 1 in 60 healthy adults but are not detectably associated with a risk of thrombosis.

Adult↗

PubMed1952