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N Saha

Publications and source records attributed to N Saha.

At least 109 records · Page 6Linked to original sources
PubMed1991

Effects of the apolipoprotein(a) size polymorphism on the lipoprotein(a) concentration in 7 ethnic groups.

Apolipoprotein(a) [apo(a)] exhibits a genetic size polymorphism explaining about 40% of the variability in lipoprotein(a) [Lp(a)] concentration in Tyroleans. Lp(a) concentrations and apo(a) phenotypes were determined in 7 ethnic groups (Tyrolean, Icelandic, Hungarian, Malay, Chinese, Indian, Black Sudanese) and the effects of the apo(a) size polymorphism on Lp(a) levels were estimated in each group. Average Lp(a) concentrations were highly significantly different among these populations, with the Chinese (7.0 mg/dl) having the lowest and the Sudanese (46 mg/dl) the highest levels. Apo(a) phenotype and derived apo(a) allele frequencies were also significantly different among the populations. Apo(a) isoform effects on Lp(a) levels were not significantly different among populations. Lp(a) levels were however roughly twice as high in the same phenotypes in the Indians, and several times as high in the Sudanese, compared with Caucasians. The size variation of apo(a) explains from 0.77 (Malays) to only 0.19 (Sudanese) of the total variability in Lp(a) levels. Together these data show (I) that there is considerable heterogeneity of the Lp(a) polymorphism among populations, (II) that differences in apo(a) allele frequencies alone do not explain the differences in Lp(a) levels among populations and (III) that in some populations, e.g. Sudanese Blacks, Lp(a) levels are mainly determined by factors that are different from the apo(a) size polymorphism.

Adult↗
PubMed1991

Biochemical characteristics of glucose-6-phosphate dehydrogenase variants among the Malays of Singapore with report of a new non-deficient (GdSingapore) and three deficient variants.

Biochemical characteristics of one non-deficient fast G6PD variant (GdSingapore) and six different deficient variants (three new, two Mahidol, one each of Indonesian and Mediterranean) were studied among the Malays of Singapore. The GdSingapore variant had normal enzyme activity (82%) and fast electrophoretic mobilities (140% in TEB buffer, 160% in phosphate and 140% in Tris-HCl buffer systems respectively). This variant is further characterized by normal Km for G6P; utilization of analogues (Gal6P, 2dG6P; dAmNADP), heat stability and pH optimum. The other six deficient G6PD variants had normal electrophoretic mobility in TEB buffer with enzyme activities ranging from 1 to 12% of GdB+. The biochemical characteristics identity them to be 2 Mahidol, 1 Indonesian and 1 Mediterranean variants and three new deficient variants.

Electrophoresis↗
PubMed1991

Influence of serum paraoxonase polymorphism on serum lipids and apolipoproteins.

One hundred and sixty-three healthy Chinese subjects of both sexes were studied for serum paraoxonase (PON) polymorphism, and levels of lipids and apolipoproteins in order to examine effects of PON alleles on these parameters. The level of serum triglyceride was significantly higher in high activity allele (PON*B) compared with that in low activity allele (PON*A) in both sexes (P less than 0.01). The subjects with PON A had significantly higher LDL cholesterol (P less than 0.05) and lower Apo A-II and ApoB levels. The influence of serum paraoxonase on serum lipids was estimated further by Spearman's rank correlation. In the males, there was a significant negative correlation of serum paraoxonase activity with total (P less than 0.05) and LDL (P less than 0.01) cholesterol levels, and positive correlation with HDL cholesterol and Apo A-II levels (P less than 0.05). Serum paraoxonase activity had a high positive correlation with serum triglyceride levels in both sexes (P less than 0.001). Serum ApoB level had a positive correlation with the enzyme activity only in females (P less than 0.01). The allelic effect of PON on these parameters was studied by multiple regression analysis. The high activity allele (PON*B) was associated with higher serum triglyceride level (P less than 0.001) and ApoB (P less than 0.001), while it had lowering influence on total cholesterol (P less than 0.05) and LDL cholesterol (P less than 0.005) in men. The average allelic effect of PON was found to be about 22% for serum triglycerides, 11% for LDL cholesterol, 14% for Apo A-II and 19% for Apo B in the present study. This study suggests a possible significant role of serum paraoxonase alleles in the metabolism of serum lipids and apolipoproteins.

Adult↗
PubMed1991

Enhancement of memory retrieval and attenuation of scopolamine-induced amnesia following administration of 5-HT3 antagonist ICS 205-930.

Experimental evidence suggests an important role of serotonin in the process of learning and memory. The present study investigated the effect of 5HT3-receptor antagonist (ICS 205-930) on retrieval of a previously learned aversive habit in the mouse. The effect of ICS 205-930 on scopolamine (3 mg/kg) induced amnesia was also studied. ICS 205-930 (1, 10 & 100 micrograms/kg) produced a dose-dependent increase in latency to cross into the dark chamber. The scopolamine induced memory impairment was significantly attenuated by ICS 205-930 (10 micrograms/kg). These results suggest that memory deficits may be susceptible to attenuation with non-cholinergic treatments.

Amnesia↗
PubMed1991

Effects of morphine on memory: interactions with naloxone, propranolol and haloperidol.

The effects of morphine on memory have been shown to be dependent on the strain of animal used and on the experimental parameters. Memory was assessed in a passive avoidance task using Swiss albino (ICRC) mice. Morphine at doses of 1, 3 and 10 mg kg-1 was administered immediately after foot shock (memory retention) or 23.5 h after foot shock (memory retrieval). Retest step-down latencies measured 24 h later showed that morphine did not affect memory retention but dose-dependently impaired retrieval of memory. Administration of naloxone 0.1 mg kg-1 antagonised the effects of morphine and impaired memory retention. Propranolol 0.3 mg kg-1 along with morphine 3 mg kg-1 impaired memory retention only while haloperidol 0.1 mg kg-1 improved the impairment of memory retrieval caused by morphine 3 mg kg-1. Glucose did not alter the effects of morphine on memory. There was no per se effect of morphine, naloxone, propranolol, glucose and haloperidol on memory at the doses used. The effect of morphine on memory retention is mediated by opioid mechanisms; however, adrenergic and dopaminergic mechanisms possibly modulate retention and retrieval of memory, respectively.

Animals↗
PubMed1991

Characterization of glucose-6-phosphate dehydrogenase variants in the Sudan--including GdKhartoum, a hyperactive slow variant.

Erythrocyte glucose-6-phosphate dehydrogenase (G6PD) was characterized in blood samples of 94 male subjects in Sudan having deficient and non-deficient electrophoretic variants. They comprised 44 GdB, 17 GdA, 19 GdB-, 11 GdA- and 3 nondeficient (GdKhartoum) variants. Biochemical characteristics including enzyme activity, electrophoretic mobility, Km for glucose-6-phosphate (G6P) and nicotinamide adenine dinucleotide phosphate (NADP), heat stability and pH optimum of all the common and deficient variants were consistent with the reported characteristics of these variants. The GdKhartoum variant had 90% mobility in TEB buffer and 100% in phosphate buffer, 120% activity, Km of 130 +/- 49 microns for G6P and 0.8 +/- 0.2 microns for NADP, lowered thermostability and an optimum pH of 7.6. This variant was not inhibited by 15 mM maleic acid, 10 mM iodoacetate and dehydro-iso-androsterone. All other variants were inhibited by dehydro-iso-androsterone but uninhibited by maleic acid and iodoacetate.

Alleles↗
PubMed1991

Apolipoprotein A-IV polymorphism in Singapore ethnic groups.

A total of 627 subjects comprising 455 Chinese, 127 Dravidian Indians and 45 Malays were investigated for serum Apo A-IV polymorphism. The frequency of Apo A-IV*2 was found to be significantly higher (p less than 0.001) in Indians (0.043) compared to that in the Chinese (0.010) and Malays (0.011). The frequency of A-IV*3 was found to be around 0.02 in all the ethnic groups. A low frequency of A-IV*4 (less than 0.01) was observed in the Chinese and Indians. The phenotypic distribution of Apo A-IV was at Hardy-Weinberg equilibrium in the three ethnic groups.

Adult↗
PubMed1991

Serum paraoxonase polymorphism in three populations of southeast Asia.

Serum paraoxonase hydrolyzes paraoxon, the principal metabolite of the insecticide parathion. Serum paraoxonase is polymorphic and controlled by two codominant alleles - PON*A and PON*B representing low and high activity, respectively. Three populations of southeast Asia comprising 194 Chinese, 159 Filipinos and 73 Dravidian Indians were investigated for serum paraoxonase polymorphism. The frequency of PON*B was found to be 0.14 in the Chinese, 0.04 in the Filipinos and 0.18 in Dravidian Indians. The distribution of the PON phenotypes was at Hardy-Weinberg equilibrium in all the three populations studied.

Aryldialkylphosphatase↗
PubMed1991

Monomorphism of formaldehyde dehydrogenase in different populations.

Blood samples from Koreans, Chinese, Hungarians and Germans were analyzed by isoelectric focusing on polyacrylamide gels and stained for formaldehyde dehydrogenase (FDH) activity. Three activity bands (one major and two minor) were observed in all blood samples studied. No distinct intra- and interpopulation differences were observed in the intensity of the three bands. Human autopsy liver samples also showed a similar three-activity band profile. An additional cathodic band was detected in a single case of autopsy liver extract from a Chinese subject. An apparent identity of FDH with the class III alcohol dehydrogenase was confirmed.

Aldehyde Oxidoreductases↗
PubMed1991

Lack of influence of maternal and fetal transferrin phenotypes and concentrations on normal fetal growth.

Influence of maternal and fetal transferrin types and concentrations on the fetal growth has been investigated in 1,174 normal full-term singleton newborns, including 352 mother-newborn pairs. No significant effect of these parameters was observed on the weight and length of the newborns. Newborn plasma transferrin concentration was not correlated with maternal plasma transferrin concentration.

Birth Weight↗
PubMed1991

Ureogenesis in a freshwater teleost: an unusual sub-cellular localization of ornithine-urea cycle enzymes in the freshwater air-breathing teleost Heteropneustes fossilis.

Sub-cellular localization of different ornithine-urea cycle enzymes was studied in the liver and kidney of a freshwater air-breathing teleost. Carbamyl phosphate synthetase, ornithine transcarbamylase, and arginase were found to be localized inside the mitochondria, and argininosuccinate synthetase and argininosuccinate lyase were found in the soluble fraction. Mitochondrial localization of arginase, a feature known in marine elasmobranchs and toadfishes, indicates the evolutionary position of H. fossilis to be different from that of present day freshwater teleosts.

Animals↗
PubMed1991

Effect of fatty diet on pharmacokinetics and pharmacodynamics of a liquid theophylline preparation in volunteers.

The effect of a standard breakfast and a fatty breakfast on the pharmacokinetics and pharmacodynamics of a theophylline liquid preparation (160 mg-single dose) was examined in 6 healthy, non-smoking male volunteers. The plasma theophylline concentrations after both standard and fatty diet were found to be comparable at each point of time and pharmacokinetic parameters like Cmax, Tmax, T1/2a, T1/2 beta and AUC0-alpha, were also comparable. However, the time taken to attain the therapeutic plasma concentration was earlier and sustained along with the standard breakfast in comparison to that with fatty breakfast. Peak change in PEFR and pulse rate was also observed earlier with the standard diet than with fatty diet. The plasma theophylline concentrations produced after both diets were insufficient to produce any detectable change in subjective symptoms like tremor palpitation, heart burn, nausea, restlessness and tenseness. However, theophylline after fatty breakfast was better tolerated than that after a standard breakfast.

Adult↗
PubMed1991

The apolipoprotein E polymorphism: a comparison of allele frequencies and effects in nine populations.

Application of uniform methods for measuring the apolipoprotein (apo) E polymorphism and plasma cholesterol levels in nine populations (Tyrolean, Sudanese, Indian, Chinese, Japanese, Hungarian, Icelandic, Finnish, and Malay) revealed significant heterogeneity among them in apo E type frequencies and mean cholesterol levels. The major apo E types in all populations were E3/2 (frequency range from 7.0% in Indians to 16.9% in Malays), E3/3 (frequency range from 39.8% in Sudanese to 72.1% in Japanese), and E3/4 (frequency range from 11.3% in Japanese to 35.9% in Sudanese). Mean cholesterol levels ranged from 144.2 mg/dl in the Sudanese to 228.5 mg/dl in the Icelandics. Two-way analysis of variance of the effect of population and apo E type on cholesterol levels showed no significantly interaction effect, indicating that the effects of apo E type on cholesterol levels do not differ significantly among the populations. The overall average excess for the epsilon 2 allele was -14.12 mg/dl (range -31.63 to -8.82 mg/dl); for the epsilon 3 allele, 0.04 mg/dl (range -1.87 to 1.58 mg/dl; and for the epsilon 4 allele, 8.14 mg/dl (range -1.71 to 13.31 mg/dl). Despite the apparent heterogeneity in these values, especially for the epsilon 4 allele, comparison of the average excesses by a method of repeated sampling with random permutations revealed no significant difference in effects among populations. These data indicate that a given apo E allele acts in a relatively uniform manner in different populations despite differences in genetic background and environmental factors.

Alleles↗
PubMed1991

Possible mechanism of haloperidol-induced enhancement of memory retrieval.

The effects of pretest administration of haloperidol on retention of a step-through passive avoidance task was studied with a 3-day training and retention test interval. Haloperidol at doses of 0.3 mg/kg and 0.5 mg/kg i.p. enhanced memory retrieval. This effect of haloperidol is possibly mediated by interaction with alpha 2-adrenergic receptors, that results in increasing the noradrenergic transmission, or it could be due to direct interaction with dopamine receptors. Yohimbine (2.5 mg/kg) also enhanced memory retrieval, as shown by haloperidol. Clonidine (0.05 mg/kg) significantly antagonized the effect of haloperidol on memory retrieval. Scopolamine (0.5 mg/kg) did not have any effect on enhancement of memory produced by haloperidol.

Animals↗
PubMed1990

Serum and red blood cell magnesium, copper, and zinc content in G6PD deficiency.

Sixty-nine G6PD-deficient and 67 normal non-deficient Chinese adult males were investigated for blood hemoglobin concentration and for serum and red cell content of magnesium, copper, and zinc. There was no significant difference in blood hemoglobin content. Both the serum magnesium and copper content were found to be significantly lower in the G6PD-deficient subjects compared to that in the non-deficient control. Serum zinc content and red cell content of all the three metals were not significantly altered in G6PD deficiency.

Adult↗
PubMed1990

Genetic studies among the Nagas and Hmars of eastern India.

A total of 148 Nagas (65 urban and 83 rural) and 81 Hmars from northeastern India were tested for 15 blood genetic markers. Both the Nagas and Hmars lacked haemoglobin variants and G6PD deficiency and had a high frequency of PGDC. This may be attributed to selective pressures operating at these loci. Genetic distance estimates using 41 alleles at 11 polymorphic loci showed appreciable heterogeneity between the urban and rural Nagas that were in line with the differences in gene frequencies. Considerable genetic admixture of the urban Nagas from the Hmar and other neighbouring populations is evident. The Nagas were found to be quite distant from the mainland Han Chinese and Malays as well as from the Bengalis and Oraons. However, they appear to be related to the Hmar and Lepcha. Evidence supporting the ethnohistoric origin of the Nagas from China or the South Seas is lacking.

Alleles↗