Electrolyte disturbances due to ouabain sensitive sodium potassium pump in erythrocytes of children with sepsis

The possible mechanism of hyponatraemia in septicaemic children was studied by measuring the intracellular red cell sodium in relation to ouabain sensitive Na(+)-K(+) pump by flame photometry. Hyponatraemia and hyperkalaemia were observed in most of the patients. There was a marked elevation in serum sodium levels and a significant reduction in serum potassium levels on recovery following therapy. The alteration in the distribution of electrolytes between plasma and erythrocytes resulted in significantly high levels of sodium and low levels of potassium within the erythrocytes of septicaemic patients which normalized on recovery. The ouabain sensitive sodium efflux rate and ouabain sensitive efflux rate constant were significantly decreased in the membranes of erythrocytes of septicaemic patients which also normalized on recovery. Our findings suggest that it is the intrinsic alterations in the transport capacity of Na(+)-K+ pump which could account for the rise in intracellular erythrocyte sodium and fall in intracellular potassium contents in septicaemic children.

GABA agonists and neurotransmitters metabolizing enzymes in steroid-primed OVX rats

The effect of intraventricular (IVT) administration of GABAA receptor agonist muscimol and GABAB receptor agonist, baclofen was examined on the activity of acetylcholinesterase (AChE), monoamine oxidase (MAO) and Na+, K(+)-ATPase in discrete areas of brain from estrogen-progesterone primed ovariectomized rats. AChE enzyme activity was increased in two subcellular fractions (soluble and total particulate) studied, with statistically significant changes in cerebral hemispheres (CH), cerebellum (CB), thalamus (TH) and hypothalamus (HT), Na+, K(+)-ATPase enzyme activity was decreased in both these fractions. MAO activity increased significantly in CH, TH and HT. The presented results suggest a functional relationship between GABAergic (inhibitory), cholinergic and monoaminergic (excitatory) systems by affecting the rate of degradation of the excitatory neurotransmitters and Na+, K(+)-ATPase.

Modulation of ouabain sensitive sodium potassium pump of erythrocytes from patients with chronic renal failure: role of acute hemodialysis

Significantly higher levels of plasma urea creatinine and potassium were observed in patients with renal failure compared to normal controls. The RBC sodium concentration was raised whereas the RBC potassium concentration was decreased in chronic renal failure. These alterations in the RBC Na+ and K+ concentrations were associated with decrease in ouabain sensitive sodium efflux rate and ouabain sensitive sodium efflux rate constant. However, there was no significant impact of acute hemodialysis on the intracellular electrolytes levels, ouabain sensitive sodium efflux rate and ouabain sensitive sodium efflux rate constant. These findings suggest an intrinsic alteration in the transport capacity of Na(+)-K+ pump which could account for the rise in intracellular sodium and fall in intracellular potassium content in the RBCs of chronic renal failure patients.

Altered physical state of p210bcr-abl in tyrphostin AG957-treated K562 cells

AG957 is a tyrosine kinase antagonist which prior studies had shown inhibits p210bcr-abl tyrosine kinase activity and K562 chronic myelogenous leukemia cell growth. We report here the effects of AG957 on the physical state of p210bcr-abl and its signaling adapter molecules Shc and Grb2 in K562 cells. After exposure to AG957, the amount of tyrosine-phosphorylated native p210bcr-abl decreases, with the appearance of a high molecular weight (> 210 kDa) p210bcr-abl. This effect is seen after [32P]orthophosphate and [35S]methionine labeling. Material suggesting the involvement of p210bcr-abl in high molecular weight complexes also appears using anti-Shc, anti-Grb2 and anti-phosphotyrosine antibodies. AG957 also acts in vitro to shift native p210bcr-abl in anti-p210bcr-abl or anti-Grb2 immunoprecipitates to higher molecular weight forms under conditions where the drug can also act as an antagonist of p210bcr-abl autokinase activity. Incubation with dithiothreitol inhibits the appearance of > 210 kDa forms of p210bcr-abl in the in vitro reaction. These results leads to the hypothesis that AG957 does not act simply as a reversible tyrosine kinase antagonist, but can alter the normal amounts and physical associations of molecules important in tyrosine kinase signaling. These effects likely reflect covalent cross-links induced by the drug.

Primary hyperparathyroidism in children

Primary hyperparathyroidism is an uncommon condition in childhood that is easily amenable to surgical treatment with excellent results. Pathologically, the parathyroid glands may show generalized hyperplasia or, more commonly, adenoma formation, the latter frequently being seen in adolescence. Two girls with solitary parathyroid adenomas and predominantly skeletal manifestations resembling rickets are reported, underlining the need to suspect and appropriately investigate these children. The literature on the subject is reviewed.

Molecular basis of pathophysiology of Indian childhood cirrhosis: role of nuclear copper accumulation in liver

Indian Childhood Cirrhosis (ICC) is a disease of abnormal copper metabolism commonly characterized by swelling and degeneration of liver cells along with the presence of orcein staining deposits of copper. Hepatic copper content of ICC patients was about 43 fold higher than those of control subjects. The data on sub-cellular distribution of copper revealed massive accumulation of Copper (73%) of total cell copper) in the nuclear fraction (455 micrograms Cu/g tissue nuclei). On further distribution of copper in nuclear fraction, the enrichment of copper in heterochromatin and euchromatin of ICC nuclei was found to be 48 and 15 fold higher over control fractions respectively. The ultra-violet spectra of heterochromatin and euchromatin isolated from ICC nuclear fraction showed a broad absorption maxima as compared to controls. Further, A260/A280 ratio was markedly lower in heterochromatin and euchromatin of ICC liver in comparison to controls. An antioxidant enzyme, catalase activity was also significantly reduced in ICC liver as compared to control. Further, DNA fragmentation studies indicated that there was significantly increased DNA fragmentation in ICC liver. Collectively, these findings suggest that massive accumulation of copper in nucleus and decrease in catalase activity was associated with DNA fragmentation in hepatocyte of ICC disease.

Tyrphostin AG17, [(3,5-Di-tert-butyl-4-hydroxybenzylidene)- malononitrile], inhibits cell growth by disrupting mitochondria

[(3,5-Di-tert-butyl-4-hydroxybenzylidene)-malononitrile] (AG17), a "tyrphostin" tyrosine kinase antagonist, was found to inhibit tumor cell growth with 50% growth inhibition ranging from 0.7 to 4.0 microM in a panel of 13 human tumor cell lines, as evaluated by tetrazolium dye reduction and inhibition of precursor incorporation into macromolecules. The promyelocytic leukemia cell line HL-60(TB), was the most sensitive with irreversible total growth inhibition after 12 h of exposure to 1.5 microM drug. Antiproliferative effects of AG17 in HL-60(TB) cells were temporally related to disruption of mitochondrial function, which occurred within 1 h after drug exposure as demonstrated by a significantly decreased mass of ATP in drug-treated cells, loss of the fluorescent mitochondrial membrane potential probe rhodamine 123, and ultrastructural examination of mitochondria using fluorescence and electron microscopy. Specific decreases of total or tyrosine-phosphorylated substrate at concentrations of the drug not affecting ATP levels were not detected. These data raise the possibility that AG17 may act in part by altering mitochondrial function and/or structure, and that impairment of mitochondrial function may be exploitable as a potentially useful mechanism to modulate tumor cell proliferation. This study also emphasizes the importance of evaluating carefully the effects of potential protein kinase antagonists, since these structures have effects in intact cells in addition to what might be expected from in vitro enzyme assays.

Noise-free chemiluminescent detection of human T cell receptor and interleukin-2 receptor genes after optimization of digoxigenin labeled probe concentration

Reduction in the background problems to improve the efficiency of nonradioactive labeling and detection procedure has been the focus of attention in the recent past for wider acceptance of the technique in nucleic acid research. We have achieved success in obtaining a relatively background free detection of single copy genes such as, T-cell receptor-delta (TCR-delta) and interleukin-2 receptor (L-2r) in human genome by using optimized concentrations of the digoxigenin labeled probes. Inclusion of such an optimization step for each probe before carrying out the actual hybridization experiment did not require any further modification in hybridization conditions and detection protocols as suggested earlier [Anal Biochem, 210 (1993) 235; Colloq Boehringer Mannheim, 2 (1991) 4.]

Jasplakinolide's inhibition of the growth of prostate carcinoma cells in vitro with disruption of the actin cytoskeleton

BACKGROUND

Jasplakinolide, a cyclodepsipeptide produced by an Indo-Pacific sponge, Jaspis johnstoni, has been reported to inhibit the growth of breast cancer cells.

PURPOSE

The effects of jasplakinolide on the proliferation of three human immortalized prostate carcinoma cell lines (PC-3, LNCaP, and TSU-Pr1) were studied. The growth-inhibitory effect of jasplakinolide on the PC-3 cell line was studied in detail to elucidate its mechanism of action.

METHODS

Cell counts were used to study growth inhibition. A protein-based microplate assay was used to assess the time of exposure needed to cause persistent growth inhibition and to study the effects of jasplakinolide analogues. Metabolic changes were assessed by following the incorporation of radiolabeled precursors. The effects of jasplakinolide on the cytoskeleton were studied by fluorescent microscopy, using rhodamine phalloidin (RP) and antibodies to cytoskeletal components. Changes in RP binding were quantified by extracting bound fluorescent material from fixed cells and measuring the amount of fluorescence in a spectrofluorometer.

RESULTS

The growth of PC-3, LNCaP, and TSU-Pr1 cells was potently inhibited by exposure to jasplakinolide for 48 hours; doses of jasplakinolide that led to 50% growth inhibition were 65 nM for PC-3 cells, 41 nM for LNCaP cells, and 170 nM for TSU-Pr1 cells. In PC-3 cells, exposure to 160 nM for 48 hours led to total growth inhibition, which persisted for several days even after drug removal. Several jasplakinolide analogues also inhibited the growth of PC-3 cells, although analogues in which the rigidity of the macrolide ring was altered were ineffective. No early changes in the synthesis of DNA, RNA, or protein or in intracellular adenosine triphosphate levels were seen in the PC-3 cells after exposure to jasplakinolide. Growth inhibition by jasplakinolide was accompanied by striking morphologic changes. Exposure for several doublings led to multinucleated cells. Further investigation of these changes in the PC-3 cells revealed a dramatic and early disruption of the actin cytoskeleton and a statistically significant decrease in RP binding. The doses of jasplakinolide, the time of exposure, and the pattern of growth inhibition by structural analogues corresponded with the changes seen in actin distribution.

CONCLUSIONS

Jasplakinolide represents a novel marine natural product with potent in vitro antiproliferative activity against human prostate carcinoma cell lines, and it appears to target the actin cytoskeleton.

IMPLICATIONS

Jasplakinolide is a potential candidate for further preclinical development and a lead structure for a novel class of therapeutic agents that can disrupt the actin cytoskeleton in mammalian cells.

Changes in glucose metabolism from discrete regions of rat brain and its relationship to reproductive failure during experimental diabetes

This study reports the effects of alloxan induced diabetes on glucose metabolism enzymes viz. Hexokinase, Lactate dehydrogenase, and Glucose-6-phosphate dehydrogenase from discrete brain regions. Enzymes activity was assayed from hypothalamic areas such as medial preoptic area and median eminence-arcuate region which have gonadotropin releasing hormone cell bodies and their terminals, respectively and other brain regions like septum, amygdala, hippocampus, and thalamus. In all the areas studied, induction of diabetes resulted in a significant decrease in particulate bound HK activity, whereas soluble HK, LDH and G6PDH activity showed increase at 3, 8, 15 and 28 days intervals. Insulin treatment of diabetic rats led to recovery in enzyme activity. Blood glucose levels increased significantly after induction of diabetes and recovery was seen after insulin treatment. The present results suggest that altered cerebral glucose metabolism may also be responsible for reproductive failure observed in diabetic rats.

Effect of alloxan-induced diabetes on Na+, K(+)-ATPase activity from discrete areas of the rat brain

The effect of alloxan-induced diabetes was studied on the activity of Na+, K(+)-ATPase enzyme which is involved in numerous reactions in the metabolism of the synaptic region, Na+, K(+)-ATPase activity was examined in brain areas such as septum, amygdala, thalamus, hippocampus, pons and medulla, and in hypothalamic areas such as medial preoptic and median eminence-arcuate region. In all these areas studied, diabetes caused a decrease in the activity of Na+, K(+)-ATPase, whereas, insulin administration reversed this effect. The present results may indicate the possible involvement of Na+, K(+)-ATPase in neuropathophysiology of diabetes.

Potent inhibition of CDC2 kinase activity by the flavonoid L86-8275

L86-8275 [(-) cis-5,7-dihydroxy-2-(2-chlorophenyl)-8[4-(3-hydroxy-1- methyl)-piperidinyl]-4H-benzopyran-4-one] directly inhibits immunoprecipitated Cdc2 kinase activity from G2/M synchronized MDA-MB-468 breast carcinoma cells and is at least 250-fold more potent than either quercetin or genistein. Purified sea-star Cdc2 kinase (IC50 = 0.5 microM) was inhibited with a similar potency to immunoprecipitated Cdc2 kinase from MDA-MB-468 cells (IC50 = 0.4 microM). This inhibition was competitive with respect to ATP (KiATP = 0.041 microM) and noncompetitive with respect to a synthetic peptide substrate, CDK1S1 (AAKAKKTPKKAKK-CONH2, KiCDK1S1 = 0.14 microM). These data suggest L86-8275 as a lead structure for the development of inhibitors of the cyclin-dependent kinases.

Tyrphostin induced growth inhibition: correlation with effect on p210bcr-abl autokinase activity in K562 chronic myelogenous leukemia

We have examined a series of tyrosine kinase inhibitors structurally related to erbstatin (tyrphostins) for inhibition of p210bcr-abl autokinase activity in vitro and for growth inhibition of chronic myelogenous leukemia (CML)K562 cells. Of the tyrphostins with IC50 for growth < 50 microM, AG814, AG946, AG952, AG896, AG953, AG956 and AG957 (structurally related to lavendustin A and piceatannol) completely inhibited p210bcr-abl kinase activity in an immune complex kinase assay. Another group of tyrphostins (AG807, AG568, AG763, AG1076, AG490, AG1318, AG556, AG1319, AG555 and AG1111) inhibits growth of K562 cells but not p210bcr-abl tyrosine kinase activity. Of the compounds which inhibit growth and p210bcr-abl tyrosine kinase activity, AG957 inhibits DNA synthesis as early as 2 h (60% inhibition at 20 microM of AG957), a time and concentration of drug where RNA and protein synthesis were not affected. AG957 inhibits p210bcr-abl tyrosine phosphorylation in living cells by 1 h without an inhibition of total protein phosphorylation. Growth inhibition by AG957 was reversible after 4 h of exposure, but irreversible after 24 h. AG957 can be considered as an important lead structure for the development of anti-bcr-abl tyrosine kinase antagonists. These data also raise the possibility that bcr-abl kinase activity is directly linked to maintenance of DNA synthesis in Philadelphia chromosome positive (Ph+) CML cells.

Effect of alloxan-induced diabetes on acetylcholinesterase activity from discrete areas of rat brain

The effect of experimental diabetes induced in rats was examined in brain areas like the septum, medial preoptic area, median eminence-arcuate region, amygdala, thalamus, hippocampus, pons and medulla. In all the areas studied, acute hyperglycemia caused an increase in the activity of acetylcholinesterase, the degradative enzyme of cholinergic system, whereas insulin administration reversed this effect. These findings suggest that the dysfunction of cholinergic system may also be involved in the diabetes associated CNS complications.

CT manifestations of tubercular mediastinal lymphadenopathy

A retrospective analysis was done of computerized tomographic (CT) scans of 29 patients with image guided histologically proven mediastinal tubercular lymphadenitis. Amongst these 19 patients were males while 10 were females in the age range of 2-65 years. Plain radiographs of all the patients revealed mediastinal lymphadenopathy. There was a high incidence of involvement of right paratracheal and tracheobronchial lymph nodes. The lymph nodes larger than 2 cm showed central low density area with peripheral enhancing walls. However, nodes less than 2 cm in size were mostly homogenous.

Acetylcholinesterase and Na+,K(+)-ATPase activities in different regions of rat brain during insulin-induced hypoglycemia

The activities of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7), responsible for hydrolysis of acetylcholine and Na+,K(+)-ATPase (Mg(2+)-dependent ATP phosphohydrolase, EC 3.6.1.3), which plays a crucial role in neurotransmission, were determined in four brain regions after 1, 2, and 3 h of insulin administration. Significant decrease in the acetylcholinesterase and Na+,K(+)-ATPase activities was observed in the soluble and total particulate fractions from cerebral hemispheres, cerebellum, brain stem, and diencephalon + basal ganglia after 1, 2, and 3 h of insulin-induced hypoglycemia. Blood glucose level decreased significantly after 1 h of insulin administration and remained at low level for 2 h thereafter, whereas, the protein content in different subcellular fractions from four brain regions did not show any significant change under this physiological stress.

Alteration of the phosphorylation state of p34cdc2 kinase by the flavone L86-8275 in breast carcinoma cells. Correlation with decreased H1 kinase activity

The flavone L86-8275 [(-)cis-5,7-dihydroxy-2-(2-chlorophenyl)-8-[4-(3-hydroxy-1-methyl)- piperidinyl]-4H-1-benzopyran-4-one] delayed the progression of aphidicolin-synchronized MDA-468 breast carcinoma cells through S phase and prevented progression through G2. L86-8275 prevented the G2-related increase in histone H1 kinase activity mediated by cyclin-dependent kinase-1 (p34cdc2 kinase). L86-8275 inhibited [32P]orthophosphate labeling of p34cdc2 threonine and tyrosine residues and decreased the phosphotyrosine content of p34cdc2. Diminution of p34cdc2 phosphotyrosine appeared selective, as a general depletion of cellular phosphotyrosine was not observed. The mass of p34cdc2 in L86-8275-exposed cells was not decreased during the period over which these effects occurred. [35S]Methionine labeling of p34cdc2 or other cellular proteins was not inhibited at concentrations that were effective for complete cellular growth inhibition. We hypothesize that L86-8275 interferes with the normal cell cycle-dependent phosphorylation of p34cdc2, resulting in decreased kinase activity and cell cycle arrest.

Effect of insulin induced hypoglycemia on acetylcholinesterase and Na+, K(+)-ATPase activity of rat heart, liver and kidney

The effect of insulin induced hypoglycemia was studied on the activities of Acetylcholinesterase (AChE) which hydrolizes acetylcholine (ACh) and Na+, K(+)-ATPase, the enzymatic version of Na+,K(+)-pump from rat heart, liver and kidney. AChE activity was decreased significantly from two subcellular fractions of all the three tissues after 1,2 and 3 hours of insulin administration (5 units/100 gm body weight) Na+, K(+)-ATPase activity was decreased in liver and kidney, whereas, a significant increase in heart ATPase activity was observed. Blood glucose level was significantly lower than control values after 1, 2 and 3 hours of insulin injection, and the protein content from these tissues did not show any significant change under this physiological stress.

Cell cycle arrest and growth inhibition by the protein kinase antagonist UCN-01 in human breast carcinoma cells

UCN-01 is a derivative of staurosporine, initially developed as a potentially selective inhibitor of the Ca(2+)- and phospholipid-dependent protein kinase C, but with the capacity to inhibit a number of tyrosine and serine/threonine kinases. UCN-01 inhibits the growth of 5 breast carcinoma cell lines with a 50% inhibitory concentration range of 30-100 nM during 6 days of continuous exposure. In MCF-7, MDA-MB453, and SK-BR-3 cells, UCN-01 is 5-fold more potent in growth inhibition than its diastereomer UCN-02, but the 2 compounds are equipotent in the inhibition of MDA-MB468 and H85787 cell growth. A differential sensitivity to a 24-h period of exposure to UCN-01 followed by drug removal and growth for 5 subsequent days was observed. The rank order for persistent inhibition of cells by UCN-01 was MCF-7, MDA-MB453 >> SK-BR-3 > H85787 > MDA-MB468. MCF-7 and MDA-MB453 cells did not resume proliferation within the 5 days after brief exposure to UCN-01. In contrast, MDA-MB468 and H85787 cells showed no net growth inhibition after a 24-h pulse of UCN-01, followed by 5 more days of growth in drug-free medium. In MDA-MB468 cells, 150 nM UCN-01 retards but does not prevent cell cycle progression through S phase, but the cells are clearly blocked from exit of G1 and entry into S. Progression through S phase is completely inhibited by 600 nM UCN-01. The development of a G1 to S block by UCN-01 in MDA-MB468 cells occurs in conjunction with inhibition of [32P]orthophosphate labeling and decreased phosphotyrosine mass of discrete cellular phosphoproteins.

Growth inhibition with reversible cell cycle arrest of carcinoma cells by flavone L86-8275

BACKGROUND

Previous studies have shown that polyhydroxylated flavonoids such as quercetin and genistein can inhibit tumor cell growth in vitro, and preliminary in vivo studies of the flavone L86-8275 have shown growth inhibition of LX529 and A549 lung carcinomas. L86-8275 [(-)cis-5,7-dihydroxy-2-(2-chlorophenyl)-8[4-(3-hydroxy-1-methyl)- piperidinyl]-4H-1-benzopyran-4-one] is a flavone of novel structure.

PURPOSE

The purpose of this study was to determine in vitro whether L86-8275 is a more potent inhibitor of growth in breast carcinoma and lung carcinoma cells than quercetin or genistein.

METHODS

We studied the effects of L86-8275 on cell growth in seven breast carcinoma cell lines and five lung carcinoma cell lines. MDA468 breast carcinoma was then selected for further study. Cell proliferation was measured by a colorimetric dye reduction assay; synthesis of DNA, RNA, and protein by incorporation of the radioactive metabolic precursors thymidine, uridine, or leucine, respectively; adenosine triphosphate (ATP) content by a luciferase-mediated bioluminescence reaction; and cell cycle progression by the use of cell-synchronizing drugs (aphidicolin and nocodazole) and flow cytometry.

RESULTS

L86-8275 was not cytotoxic to stationary-phase cells but reversibly inhibited the growth of cells in exponential growth phase. At concentrations of 25-160 nM, L86-8275 inhibited growth of human breast and lung carcinoma cell lines by 50%. MDA468 breast carcinoma cells were 60-fold and 400-fold more sensitive to L86-8275 than to quercetin and genistein, respectively. By 24 hours after addition of L86-8275, DNA synthesis in MDA468 cells was inhibited by greater than 95%, protein synthesis by 80%, and RNA synthesis by 40%-60%, under conditions that preserved cellular ATP levels at approximately 80%-90% of control values. When MDA468 cells released from aphidicolin-induced cell cycle arrest were exposed to 200 nM L86-8275, they completed the S phase but arrested in G2. When cells released from nocodazole-induced cell cycle arrest were exposed to 200 nM L86-8275, they completed mitosis but arrested in G1.

CONCLUSIONS

L86-8275 is a potent, yet reversible, growth-inhibitory flavone that can selectively block cell cycle progression in vitro at more than one point in the cell cycle.

IMPLICATIONS

These findings suggest that L86-8275 is a candidate for further preclinical development, as well as a model for the synthesis of other flavonoids that might potently delay cell cycle progression to achieve inhibition of tumor growth. Future studies need to address optimal schedules for antiproliferative activity in vivo and inhibition of clonogenic activity.

Acute starvation decreases acetylcholinesterase activity in different regions of rat brain

The activity of acetylcholinesterase (AChE) was assayed spectrophotometrically in four brain regions of rats that had been deprived of food for 96 h. A significant decrease in the total AChE activity (by 4-45%) as well as in its specific activity (by 14-28%) was observed in the supernatant and total particulate fractions from cerebral hemispheres, cerebellum, brainstem and diencephalon + basal ganglia. Similarly, blood glucose, body weight and protein content of subcellular fractions from most brain regions showed decreases after starvation.

Growth inhibition by cholera toxin of human lung carcinoma cell lines: correlation with GM1 ganglioside expression

The effect of cholera toxin (CT) on the growth of 12 small cell lung carcinoma (SCLC) and 15 non-small cell lung carcinoma (NSCLC) cell lines is presented. CT inhibited the growth of nine SCLC cell lines (concentration for 50% inhibition of growth, 27-700 ng/ml), all of which had abundant expression of GM1 ganglioside, the surface receptor for CT. CT-resistant SCLC all had greatly decreased GM1 expression. In contrast, CT inhibited the growth of only four of 15 NSCLC cell lines. Seven of the 11 CT-resistant NSCLC had levels of GM1 comparable to CT-sensitive NSCLC or SCLC. In a limited panel of cell lines, cyclic AMP (cAMP) agonists including forskolin, 8Br[cAMP], and dibutyryl[cAMP] did not consistently reproduce CT-mediated inhibition of cell growth, nor did these compounds overcome resistance of cells to the growth inhibitory effects of CT. Expression of the RI and RII regulatory subunits of cAMP-dependent protein kinase was similar in CT-resistant and CT-sensitive SCLC or NSCLC cell lines. In the presence of isobutylmethylxanthine, intracellular cAMP levels induced by CT in a CT-resistant, GM1(+) NSCLC cell line were comparable to those achieved in a CT-sensitive NSCLC cell line. We conclude that inhibition of lung carcinoma cell growth by CT in all cases requires expression of GM1, and in the case of SCLC cell lines the presence of GM1 is sufficient. In NSCLC cell lines, expression of GM1 is not sufficient for growth inhibition by CT. These findings imply refractoriness to growth inhibition by cAMP in GM1(+), CT-resistant NSCLC cell lines and the possibility of non-cAMP-related mechanisms for growth inhibition in CT-sensitive cell lines.

Effect of training on weight and certain physiological parameters of Indian female hockey players with respect to their field positions

The present study was conducted on 18 female players of the Punjabi University hockey team during their camp held at Punjabi University from 4.10.1988 to 24.10.1988; before participating in the Inter-varsity competition held at Ranchi. Weight, heart rate and blood pressure of each subject was taken before doing the exercise on the treadmill. The players were asked to run on the treadmill for four minutes at the speed of 10 km/hr. Recovery heart rate and blood pressure were also taken. All these tests were taken twice on each player, i.e. initially at the commencement of the training and finally at the completion of the training camp. It has been observed that there is a reduction of body weight in all the categories of players, the maximum being in halves (2.5 kg). There is an improvement in the percentage recovery in the heart rates of all the categories of players except the halves where the recovery is much less at the end of the training camp as compared to the values in the beginning of the camp.

Effect of acute starvation on monoamine oxidase and Na+,K(+)-ATPase activity in rat brain

The activities of monoamine oxidase (MAO), responsible for oxidative deamination of many biogenic amines, and Na+, K(+)-ATPase, which plays a crucial role in the release mechanism of neurotransmitters, were determined in rat brain after acute starvation. They were assayed biochemically from four different regions of the brain in two subcellular fractions. Acute starvation decreased the activity of MAO, whereas the Na+,K(+)-ATPase activity was increased. An effect of starvation was also seen on the blood glucose level, body wt, and the protein content of different brain regions. Starvation or normal dietary fluctuations of certain nutrients that exert precursor influence over neurotransmitter synthesis are important to the brain, and contribute to its regulation of both neuroendocrine response and behavior. A rise in the substrate level, i.e., ATP, as a result of increased utilization of ketone bodies and low level of monoamines in the brain after acute starvation, may be the underlying factor for increasing the activity of Na+,K(+)-ATPase in rat brain. These results suggest that, probably, certain adaptive mechanisms become operative in the brain under disturbed physiological conditions.

Morphine-induced inhibition of ovulation in normally cycling rats: neural site of action

Intracerebral injection of morphine (3 micrograms/0.2 microliter of solvent) on the day of proestrus at 1200 hr bilaterally in the medial preoptic area (mPOA) and median eminence-arcuate (ME-ARC) region inhibited ovulation in the cycling female rats. The morphine antagonist, lethidrone (2 micrograms/0.2 microliter of solvent) when injected in the mPOA and ME-ARC region followed by intraperitoneal morphine (3 mg/100 g body weight) administration, was found to reverse the ovulation blocking action of this opiate. Implantation site at which morphine was effective in blocking ovulation were restricted to a narrow medial band encompassing the mPOA and ME-ARC region. Our data are consistent with the view that the endogenous opioid peptides in mPOA and ME-ARC region of the hypothalamus may be involved in the physiological regulation of the central neural events which lead to ovulation in the rat.

Changes in hexokinase isoenzymes in regions of rat brain during thyroid deficiency

In this work, activities of hexokinase isoenzymes Type I and Type II were measured in the soluble and particulate fractions from the brain regions (cerebral hemispheres (cerebrum), cerebellum and brain stem) of the thyroidectomized adult rats as well as of the thyroidectomized rats administered with triiodothyronine. Thyroidectomy generally decreased the hexokinase activity associated with particulate and soluble fractions. Hexokinase Type II isoenzyme was more affected than the Type I isoenzyme. Administration of triiodothyronine to the hypothyroid rats abolished the effect of thyroidectomy. Adult brain enzymes have been generally considered not be affected by thyroid hormones. The data obtained in this work are suggestive of an effect of thyroid hormones on hexokinase in the adult brain. Since the effects of thyroidectomy on the energy metabolism of the heart tissue are well known, the heart tissue was also studied for comparison.

Blockade of ovulation by prostaglandins synthesis inhibitor in medial preoptic area

Indomethacin, a known inhibitor of prostaglandins synthesis, injected into the medial preoptic area on the day of proestrus blocked ovulation in regularly cycling female rats. This finding provides evidence for a facilitatory role of endogenous prostaglandin synthesis, in the medial preoptic area, in the process of ovulation.

Metabolic activity of lysosomes in tin-intoxicated regenerating rat liver

The metabolic activity of lysosomes was monitored by assaying the lysosomal enzymes. DNase, RNase, acid phosphatase and cathepsin in rat liver regenerating after partial hepatectomy at various intervals after the operation. Results of the present study demonstrate that the activities of lysosomal enzymes are increased significantly during the process of rapid regeneration, especially at 24 h and 48 h. A small rise in enzymatic activities was noticed at 36 and 72 h of regeneration, leading towards normalisation at 168 h. Administration of tin(II) tartrate (25 mu mol Sn2+/100 gm body wt.) significantly increased the DNAse and RNAse activity at 24 h of the regeneration, while a decrease was noticed in acid phosphatase activity. An increase was also found in the catheptic activity of tin-treated hepatectomized rats. It can thus be concluded that an increased metabolic activity of lysosomes is reflected by the increased activity of its hydrolytic enzymes during the regeneration, and tin at low concentrations is helpful to this process. Further work is in progress to gain insight into the other metabolic activity of the lysosomes during the process of regeneration.

Influence of polyaminocarboxylic acids on the removal of manganese-54 from the body organs of sham-operated and partially hepatectomized rats

EDTA, 1,2-cyclohexylenediamine tetra-acetic acid (CDTA), hexamethylene 1,6-diamine N,N,N',N'-tetra-acetic acid (HDTA), diethylene-triamine pentaacetic acid (DTPA) and nitrilotriacetic acid (NTA) were examined for the removal of manganese-54(54Mn) from some organs of sham-operated and partially hepatectomized rats in early manganese (Mn) poisoning. CDTA was found to be most effective in removing 54Mn from the liver of both sham-operated and hepatectomized rats. These chelating agents also lowered the Mn levels in kidney, spleen and brain of poisoned rats. Although a significantly higher accumulation of Mn was observed in hepatectomized rats, there was no significant difference in the efficiency of the chelating agents in removing Mn from the body organs of poisoned animals of both the sham-operated and hepatectomized groups. An attempt has been made to seek a possible correlation between % removal of Mn by various polyaminocarboxylic acids and their corresponding stability constants.

Changes in hexokinase isoenzymes in regions of rat brain during insulin-induced hypoglycemia

Activities of hexokinase isoenzymes were determined during insulin-induced hypoglycemia in soluble and total particulate fractions from three regions of rat brain. Type I hexokinase isoenzyme activity showed a small decrease in both soluble and particulate fractions from the cerebral hemispheres. In cerebellum and brain stem, however, Type I isoenzyme showed a decrease only in the soluble fraction. A significant increase was observed in hexokinase Type II isoenzyme from both the fractions, in all the three brain regions 1 h after insulin administration.