Evidence that a ryanodine receptor triggers signal transduction in the osteoclast.

We have investigated the effect of the alkaloid ryanodine on the release of intracellularly stored Ca2+ in response to activation of the osteoclast Ca2+ receptor by the surrogate agonist, Ni2+, Ni2+ (6 mM) in the presence of ethylene-glycol bis-(aminoethyl ether) tetraacetic acid (EGTA) (1.2 mM) and valinomycin (5 microM) induced a transient elevation of cytosolic [Ca2+] in fura 2-loaded osteoclasts. This transient was superimposed upon a small steady elevation of cytosolic [Ca2+] induced by the initial application of valinomycin alone.

The osteoclast Ca2+ receptor is highly sensitive to activation by transition metal cations.

We report changes in the cytosolic Ca2+ concentration ([Ca2+]i) of single rat osteoclasts in response to Ca2+ receptor activation by micromolar concentrations of the transition metal cations, Cd2+ and Ni2+. The extracellular application of Cd2+ or Ni2+ resulted in a concentration-dependent elevation of cytosolic [Ca2+]. Each monophasic [Ca2+]i response consisted of an initial rapid rise of [Ca2+]i to a peak value followed by an exponential decay.

Activation and inactivation of the osteoclast Ca2+ receptor by the trivalent cation, La3+.

We report changes in the cytosolic Ca2+ concentration ([Ca2+]i) of single rat osteoclasts in response to Ca2+ receptor activation by micromolar concentrations of the lanthanide metal cation, La3+. The extracellular application of La3+ induced a concentration-dependent elevation of cytosolic [Ca2+]. Prior conditioning of osteoclasts with La3+ resulted in a concentration-dependent reduction of the response to a subsequent application of a maximally effective concentration of Ni2+, a known agonist of the osteoclast Ca2+ receptor.

Partial purification and immobilization of ribonuclease T2.

A simple procedure, consisting of water extraction, heat treatment at pH 2.0, negative adsorption on DEAE-cellulose at pH 4.9, and concanavalin A-Sepharose chromatography, was developed for the partial purification of ribonuclease (RNase) T2 from taka-diastase powder with an overall yield of 5.

Active-site characterization of S1 nuclease. I. Affinity purification and influence of amino-group modification.

A simple procedure, involving heat-treatment, DEAE-Sephadex, AMP-Sepharose and Bio-Gel P-60 chromatography, was developed for the purification of S1 nuclease to homogeneity from commercially available Takadiastase powder. Chemical modification of the amino groups of purified S1 nuclease revealed that lysine is essential for single-stranded DNAase, RNAase and phosphomonoesterase activities associated with the enzyme. The kinetics of inactivation suggested the involvement of a single lysine residue in the active site of the enzyme.

Endothelin inhibits osteoclastic bone resorption by a direct effect on cell motility: implications for the vascular control of bone resorption.

The abundance of endothelin (ET)-producing endothelial cells in bone marrow and the proximity of these cells to bone-resorbing osteoclasts prompted us to evaluate the action of ET-1 on osteoclast function. Osteoclasts disaggregated from neonatal rat long bones were settled onto devitalized cortical bone substrate, and resorption was quantified by morphometry. The supernatant tartrate-resistant acid phosphatase activity was determined by a spectrophotometric method using paranitrophenol phosphate as substrate.

Is the osteoclast calcium "receptor" a receptor-operated calcium channel?

Elevated extracellular calcium levels ([Ca2+]e) inhibit osteoclast function by elevating cytosolic free calcium levels ([Ca2+]i), presumably via the activation of a surface Ca2+ "receptor". It is unclear whether or not Ca(2+)-induced [Ca2+]i elevation involves the direct gating, by the putative "receptor", of a divalent cation channel. The results show that [Ca2+]i elevation in response to elevated [Ca2+]e comprises a distinct component of Ca2+ influx, the magnitude of which can be decreased and increased, respectively, by depolarising (100 mM-[K+]) and hyperpolarising (1 microM-[valinomycin]) the osteoclast membrane.

Kinetics of virus spread and changes in levels of several cytokine mRNAs in the brain after intranasal infection of rats with Borna disease virus.

We have used the reverse transcriptase-polymerase chain reaction technique to gain insight into the pathogenesis of encephalitis caused by Borna disease virus (BDV). RNA specific for BDV was first detected in the olfactory bulb of intranasally infected rats at 6 days postinfection (p.i.

A quantitative description of components of in vitro morphometric change in the rat osteoclast model: relationships with cellular function.

We describe the in vitro morphometric changes shown by rat osteoclasts that accompany their functional responses to the application of a range of regulatory agents of known physiological importance. We introduce a cellular motility parameter, mu, which was defined through a quantification of retraction-protrusion behaviour. This was used in conjunction with a net cell retraction, rho, which is derived from the change in total cell area following the application of an agent.

Translation of messenger RNA from canine tracheal epithelial cells: identification of mucin core protein.

A high-molecular-weight mucin (Mr approximately 11.0 x 10(6)) was purified from canine tracheal pouch secretions. The mucin was deglycosylated by treatment with trifluoromethane sulfonic acid for 8 h at 8 degrees C and subsequently with alpha-N-acetylgalactosaminidase.

Macromolecular properties and polymeric structure of canine tracheal mucins.

Two high-Mr mucus glycoproteins (mucins), CTM-A and CTM-B, were highly purified from canine tracheal pouch secretions, and their macromolecular properties as well as polymeric structure were investigated. On SDS/composite-gel electrophoresis, a diffuse band was observed for each mucin. Polyacrylamide-gel electrophoresis using 6% gels also showed the absence of low-Mr contaminants in the mucins.

Direct entry of rabies virus into the central nervous system without prior local replication.

Rabies virus pathogenesis was studied in a mouse model by inoculation of the masseter muscle. At different intervals, the masseter muscle, trigeminal ganglia, and brain were analyzed for virus-specific RNA with a polymerase chain reaction assay, which revealed that as early as 18 h postinfection (p.i.

Type O renal glucosuria.

We observed a 7-year-old boy with virtual absence of renal tubular glucose reabsorption (type O renal glucosuria). Glucose titration studies in his family revealed severe type A renal glucosuria in a younger brother, a mild type A defect in the mother and normal glucose reabsorption in the father; thus a spectrum of renal glucose transport defects was observed in members of the same family.

Polymeric structure of human respiratory mucin: studies on two protein components released upon reduction of disulfide bonds.

A major mucus glycoprotein (mucin) was purified from the tracheobronchial secretions of an asthmatic patient. Upon SDS-composite gel electrophoresis, the purified native (non-reduced) mucin gave a single band. SDS-gel electrophoresis on 6% polyacrylamide gels showed the absence of low molecular mass protein contaminants.

Age for measles immunization seroconversion after measles vaccination at 6-8 months of age--a randomized controlled trial.

The objective of the study was to compare the effectiveness of measles vaccine by seroconversion in vaccinated children with non-vaccinated children of 6 to 8 months age group in a city slum community so as to study the feasibility of advancing the age of immunization. Live attenuated lyophilized Schwartz strain of measles vaccine was used. Hemagglutination inhibition (HI) antibody was estimated.

Over-expression of the epidermal growth factor receptor in human breast cancer cells fails to induce an estrogen-independent phenotype.

An association exists in primary human breast tumors between high epidermal growth factor receptor (EGFR) expression and a reduced number or even absence of estrogen receptors (ER). To determine whether an increase in EGFR expression might alter the estrogen responsiveness of an ER-positive human breast cancer cell line, ZR 75-1 cells were cotransfected with a plasmid containing the full-length cDNA for the human EGFR under the transcriptional control of the Harvey murine sarcoma virus (HaMSV) long terminal repeat (LTR) and with a pSV2neo plasmid. Two of the isolated G418-resistant clones were found to constitutively express EGFR levels 15- to 60-fold higher than those found on nontransfected ZR 75-1 cells.

Prevalence of placentally transmitted antibodies for measles in infants 3 to 11 months old in an urban slum community.

Upto 35% of infants aged between 6 and 11 months are infected with measles in India with its associated high morbidity and mortality. The objective of the study is to know the waning pattern of placentally transmitted antibodies (PTA) for measles so that the age at which children are likely to become susceptible to measles infection could be identified. A cross-sectional serological survey of children aged 3 to 11 months in one of the Integrated Child Development Service (ICDS) area in Madras city slums was done.

Evidence of hydrophobic domains in human respiratory mucins. Effect of sodium chloride on hydrophobic binding properties.

Hydrophobic binding properties of purified human respiratory mucins were studied by the fluorescence probe technique using mansylphenylalanine (Mns-Phe) as the fluorescent probe. Mucins were purified from tracheobronchial secretions of cystic fibrosis (CF) and asthmatic patients, as well as from individuals with normal lungs, according to a protocol earlier established in our laboratory. Purified mucins were subjected to reduction-alkylation and Pronase digestion to study the effects of these treatments on the hydrophobic properties of the mucins.

Plasma renin activity in shock due to aluminium phosphide poisoning.

Plasma renin activity (PRA) was estimated in 30 patients with aluminium phosphide (AIP) poisoning (study group) admitted in shock. Ten patients in shock other than due to AIP poisoning (Group II A) and 20 normal healthy subjects (Group II B) served as controls. The PRA was significantly higher in the study group and group II A as compared to normal healthy subjects (p less than 0.

Radio-active iodine uptake in vitiligo.

Vitiligo and thyroid disease are commonly associated disorders. Twenty-two clinically euthyroid vitiligo patients were studied for functional assessment of thyroid by radioactive iodine uptake assay. Half of them showed abnormal uptake values at 24 hours.

Preparation and properties of RNase T2 immobilized on concanavalin A-sepharose.

Partially purified RNase T2 (EC 2.7.7.

Infection with a TGF-alpha retroviral vector transforms normal mouse mammary epithelial cells but not normal rat fibroblasts.

A cDNA clone of human transforming growth factor alpha (TGF-alpha) was introduced into two different retroviral vectors under the transcriptional control of either the viral LTR, vector 1520, or an internal mouse metallothionein-1 promoter, vector 1522. Infection of normal rat kidney fibroblasts (NRK-49F) and mouse mammary epithelial cells (NOG-8), followed by selection, allowed isolation of individual colonies expressing human TGF-alpha. NRK-49F and NOG-8 1520 infectants conditioned their media with equivalent amounts of TGF-alpha protein but responded differently to autocrine stimulation.

Influence of lectin concentration on the catalytic properties of S1 nuclease bound to Concanavalin A-sepharose.

Partially purified S1 nuclease was bound through its carbohydrate moiety to Con A-Sepharose containing increasing amounts of lectin. The retention of activity was high, varying essentially from 75% on the "low lectin" matrix (1 mg Con A/mL of Sepharose), to no detectable activity on the "high lectin" matrix (8 mg Con A/mL of Sepharose). However, approximately 50% activity could be restored in "high lectin" matrix when the coupling was carried out in the presence of glucose, suggesting that the loss of activity on the "high lectin" matrix is caused by conformational changes brought about by the multiple attachment of the enzyme to the matrix.