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PubMed1997

Sensitivity of blood pressure and renin activation during sodium restriction.

The objective of the present study was to explore the interrelationships among cumulative sodium loss, renin activation, and blood pressure changes during sodium restriction in essential hypertensive patients. Specifically, we wanted to know whether the degree of sodium sensitivity of blood pressure depends on renin activation during steady state or on initial renin activation during the first days of sodium restriction. Sixty-seven untreated essential hypertensive patients were admitted to a metabolic ward for 8 days and put on a sodium restricted diet of 55 mmol/d from the second to the last day. Urinary excretions of sodium, potassium, and creatinine were determined along with mean arterial pressure and weight during 7 days. Besides measurements in steady state condition (after 7 days), active plasma renin concentration, aldosterone, and catecholamines were also assessed during the first 3 days of sodium restriction. Analyzable data are available for 55 patients. Baseline sodium excretion and the activation of renin during the first 3 days both appeared to be predictors of total sodium loss after 7 days. Changes in blood pressure were not related to changes in sodium balance, but they were to baseline blood pressure, baseline norepinephrine, and renin activation during the early phase of sodium restriction. In addition, blood pressure appeared to fall more when the normal relationship between sodium loss and early (but not late) activation of renin was disturbed. We conclude that sodium sensitivity of blood pressure during sodium restriction is associated with a relative unresponsiveness of the renin system during the early phase of sodium loss rather than to absolute renin levels during steady state.

Adult↗

PubMedDate not supplied

Endogenous angiotensin-aldosterone-pressure relationships during sodium restriction.

The effects of moderate restriction of dietary sodium and potassium supplementation on plasma levels of renin, angiotensin II, aldosterone, and cortisol and on arterial pressure were studied in 12 patients with mild essential hypertension. To define hormone-blood pressure relationships, venous hormone levels were measured hourly and intra-arterial pressure continuously for 24 hours after 4 to 6 weeks of sodium restriction, 4 to 6 weeks of potassium supplementation, and a similar period of control diet. Our results show that compared with the control diet, moderate sodium restriction was associated with increased levels of aldosterone but no overall change in renin, angiotensin II, or cortisol levels. Further, slopes of regression lines relating log renin and log angiotensin II to aldosterone were increased, as were log cortisol/aldosterone regression lines. On the contrary, regression lines of log renin and log angiotensin II versus arterial pressure were unaltered by sodium restriction. Hormone and blood pressure relationships were not changed by the potassium supplemented diet. Although confirmatory data are needed, our findings suggest that moderate sodium restriction enhances aldosterone responsiveness to endogenous angiotensin II and adrenocorticotropic hormone without diminishing the pressor activity of endogenous angiotensin II. These results may explain in part the disappointingly small hypotensive effect of modest sodium restriction in mild essential hypertension.

Adult↗

PubMed1993

Sodium restriction increases aldosterone biosynthesis by increasing late pathway, but not early pathway, messenger ribonucleic acid levels and enzyme activity in normotensive rats.

To determine whether changes in dietary sodium intake modify the early and/or late pathways of aldosterone biosynthesis, we studied in Sprague-Dawley rats the effect of sodium restriction on early (conversion of cholesterol to pregnenolone) and late (conversion of corticosterone to aldosterone) pathway activity and on the mRNA levels for the enzymes regulating these steps. Sodium restriction increased basal and angiotensin-II-stimulated aldosterone output from isolated zona glomerulosa cells by 5- to 9-fold. This increase in aldosterone output did not appear to be due to changes in the conversion of cholesterol to pregnenolone or in the mRNA levels of the early pathway enzyme, cholesterol side-chain cleavage cytochrome P-450. In contrast, sodium restriction increased the conversion of corticosterone to aldosterone 10-fold and increased by over 10-fold the mRNA levels of the late pathway enzyme aldosterone synthase. Sodium restriction had no effect on zona glomerulosa levels of 11 beta-hydroxylase mRNA. In two other normotensive rats, Dahl salt-resistant and Wistar Kyoto, sodium restriction again specifically increased aldosterone synthase mRNA without altering 11 beta-hydroxylase or cholesterol side-chain cleavage cytochrome P-450 mRNA levels. Thus, it appears that sodium restriction specifically increases late pathway aldosterone synthase mRNA levels, resulting in an increase in enzyme levels, followed by an increase in late pathway activity and an increase in aldosterone output.

Aldosterone↗

PubMed2004

Endocrine changes in full-term pregnancies and pregnancy loss due to energy restriction in the common marmoset (Callithrix jacchus).

Common marmosets, a New World primate, respond to a modest energy restriction with early termination of the pregnancy. Within female marmosets, comparisons (n = 6) between a normal, term pregnancy and a restriction-induced aborted pregnancy were used to establish cortisol, free estradiol, and chorionic gonadotropin (CG) as urinary markers of placental and fetal function under these two conditions. Abortions occurred 11-47 d after a 25% energy reduction during midpregnancy for all females. Cortisol concentrations were significantly lower in the last 2 wk for the restricted pregnancy than for matched samples in the normal term pregnancy. Both estradiol and estrone were examined in free and conjugated forms. Only free estradiol showed a significant reduction in mean concentrations during midpregnancy for the restricted females compared with their normal, term pregnancies. Mean CG levels from each female served as an independent marker of placental differentiation and function. CG levels were significantly lower during the 2 wk before abortion compared with matched days from a normal, term pregnancy. These data provide evidence that estradiol and cortisol are useful markers of placental and fetal viability in the common marmoset, and their reduced concentration following energy restriction suggests that restriction is not acting as a classical stressor by increasing cortisol and, subsequently, estradiol concentration.

Abortion, Spontaneous↗

PubMed1999

Restriction fragment length polymorphism analysis of the F gene of Newcastle disease viruses isolated from chickens and an owl in Taiwan.

To provide information on the epidemiology of Newcastle disease (ND) of poultry in Taiwan, ND virus isolates from chickens and an owl were investigated by restriction site analysis and sequencing of their gene. A 1,349 base fragment of the F (fusion protein) gene was amplified by reverse transcription-polymerase chain reaction (RT-PCR). The PCR products were analyzed using restriction endonucleases, HinfI, BstOI, and RsaI. Three strains isolated from chickens during the 1995 epidemic outbreak had the same restriction sites as that of a 1994 isolate; the number of the restriction sites of HinfI, BstOI, and RsaI were 4, 2, and 4, respectively. In the F gene of the strain isolated from an owl during the same outbreak an additional restriction site of HinfI was found. The 1991 isolate had only 3 restriction sites. The F gene of the owl isolate was amplified by RT-PCR and followed by direct sequencing. The deduced amino acid sequence at the cleavage site of the F protein was of virulent strains, 112R-R-Q-K-R-F117. The F gene of Ow/Tw/2209/95 was phylogenetically most closely related to that of Ck/Tw/2137/95 isolated from the same outbreak. The present results indicate that the causative virus of the 1995 ND outbreak had already been present in Taiwan.

Animals↗

PubMed2004

Sir2-independent life span extension by calorie restriction in yeast.

Calorie restriction slows aging and increases life span in many organisms. In yeast, a mechanistic explanation has been proposed whereby calorie restriction slows aging by activating Sir2. Here we report the identification of a Sir2-independent pathway responsible for a majority of the longevity benefit associated with calorie restriction. Deletion of FOB1 and overexpression of SIR2 have been previously found to increase life span by reducing the levels of toxic rDNA circles in aged mother cells. We find that combining calorie restriction with either of these genetic interventions dramatically enhances longevity, resulting in the longest-lived yeast strain reported thus far. Further, calorie restriction results in a greater life span extension in cells lacking both Sir2 and Fob1 than in cells where Sir2 is present. These findings indicate that Sir2 and calorie restriction act in parallel pathways to promote longevity in yeast and, perhaps, higher eukaryotes.

Caloric Restriction↗

PubMed2005

Changes in insulin resistance following bariatric surgery: role of caloric restriction and weight loss.

The prevalence of type 2 diabetes mellitus (T2DM) and obesity in the western world is steadily increasing. Bariatric surgery is an effective treatment of T2DM in obese patients. The mechanism by which weight loss surgery improves glucose metabolism and insulin resistance remains controversial. In this review, we propose that two mechanisms participate in the improvement of glucose metabolism and insulin resistance observed following weight loss and bariatric surgery: caloric restriction and weight loss. Nutrients modulate insulin secretion through the entero-insular axis. Fat mass participates in glucose metabolism through the release of adipocytokines. T2DM improves after restrictive and bypass procedures, and combinations of restrictive and bypass procedures in morbidly obese patients. Restrictive procedures decrease caloric and nutrient intake, decreasing the stimulation of the entero-insular axis. Gastric bypass (GBP) operations may also affect the entero-insular axis by diverting nutrients away from the proximal GI tract and delivering incompletely digested nutrients to the distal GI tract. GBP and biliopancreatic diversion combine both restrictive and bypass mechanisms. All procedures lead to weight loss and decrease in the fat mass. Decrease in fat mass significantly affects circulating levels of adipocytokines, which favorably impact insulin resistance. The data reviewed here suggest that all forms of weight loss surgery lead to caloric restriction, weight loss, decrease in fat mass and improvement in T2DM. This suggests that improvements in glucose metabolism and insulin resistance following bariatric surgery result in the short-term from decreased stimulation of the entero-insular axis by decreased caloric intake and in the long-term by decreased fat mass and resulting changes in release of adipocytokines. Observed changes in glucose metabolism and insulin resistance following bariatric surgery do not require the posit of novel regulatory mechanisms.

Biomarkers↗

PubMed1998

Mutations of ret proto-oncogene in 3 Korean families with MEN 2A: clinical use of new restriction sites for genetic diagnosis.

Abnormalities in the ret proto-oncogene are found in several disorders such as multiple endocrine neoplasia (MEN) 2, sporadic medullary thyroid cancer, congenital megacolon and papillary thyroid cancer. In MEN 2A or 2B, early genetic diagnosis before the development of clinical tumors is crucial for the cure of the disease. We studied mutations of ret proto-oncogene in 3 Korean families with MEN 2A and searched for new restriction sites that could be used for genetic diagnosis. By direct sequencing of exon 10 and 11 harboring 'hot' spots, heterozygous point mutation was detected at positions translating cysteine codon in all 3 families. In 2 families, mutations at codon 634 in exon 11 were found (from TGC to CGC or TAC), yielding a new CfoI or RsaI restriction site. In one family, a mutation was located at codon 618 in exon 10 (from TGC to CGC), generating a new CfoI restriction site. These new restriction sites were used in detecting 2 undiagnosed family members without clinical symptoms or signs. In one of them, thyroidectomy was performed to disclose a small medullary thyroid cancer. These results indicate that Korean MEN 2A patients have germ-line mutations in the ret protooncogene at the cysteine residues like patients of other races, and the strategy employing direct sequencing to find mutations at 'hot spot' and search for ensuing new restriction sites could be a useful approach for the molecular diagnosis of genetic diseases accompanied by mutations in restricted areas of disease genes such as MEN 2.

Adrenalectomy↗

PubMed2001

Inhibition of restriction enzyme's DNA sequence recognition by PUVA treatment.

Applying various restriction enzymes on a specially designed 1.5 kb DNA fragment revealed that the inhibitory effects of psoralens + UVA irradiation (PUVA) treatment on restriction endonuclease activities are caused by recognition inhibition. In this study restriction enzymes that have a 5'-TpA sequence at the cleaving site (KpnI, XbaI, PmeI and DraI), and the noncleaving site (PacI) in recognition sites, or have two 5'-TpA sequences at the recognition site, and a nonspecific sequence between the recognition and the cleaving sites (BciVI), were inhibited by PUVA treatment. Most of the other restriction enzymes used in this study, which do not have a 5'-TpA sequence at their restriction site, were not inhibited by PUVA treatment, although a 5'-TpA sequence is located adjacent (SmaI) or very close (BamHI, SacI and PstI) to the recognition and cleaving sites for these enzymes. Because SphI, which does not have 5'-TpA at its restriction site, was strongly inhibited by PUVA treatment, the 5'-CpA sequence is suggested to be a new binding site of psoralens after UVA irradiation.

Base Sequence↗

PubMed1997

Effect of aging and caloric restriction on intestinal sugar and amino acid transport.

The incidence of intestinal nutrient malabsorption increases with age. Therefore, an important question is whether there are age-related changes in intestinal nutrient absorption which may contribute to a decline in absorptive capacity. Sugar and amino acid transport per mg intestine generally decreases with age. The proximate mechanism underlying this age-related decrease in transport activity is a decrease in number of transporters per mg. This reduction in transporter number can be caused by age-related changes in cell proliferation rates which, in turn, can alter the ratio of absorptive to nonabsorptive cells. The age-related change in proliferation rates typically increases intestinal mass. There seems to be no age-related changes in the steady state levels of transporter mRNA. Aging also modestly impairs the ability of intestinal nutrient transport systems to adapt to changes in dietary conditions. Caloric restriction is the only procedure known to consistently increase the lifespan of mammals. Chronic caloric restriction markedly enhances intestinal nutrient transport per mg without affecting intestinal mass. Since body weight decreases with caloric restriction, there is a dramatic increase in intestinal absorptive capacity normalized to body weight. This suggests that an increase in intestinal nutrient absorption may be a critical adaptation to caloric restriction. There is a need to perform in vivo transport studies during senescence, to distinguish between acute and chronic effects of caloric restriction, and to identify hormones that may mediate aging and caloric restriction effects on intestinal nutrient transport.

Aging↗

PubMed1995

Onset of lay related to multiphasic growth and body composition in White Leghorn pullets provided ad libitum and restricted diets.

Growth of the body as a whole and of parts of the reproductive tract of White Leghorn pullets that ate ad libitum and restricted diets were analyzed by a multiphasic growth function. Parameter estimates were related to onset of lay. Chemical body compositions at defined stages of pubertal growth were related to the development of the reproductive organs. Data of pullets that had been restricted in one of two rearing periods (0 to 6 and 7 to 18 wk of age) were used. In each period, pullets were fed a low-lysine diet or a daily restricted amount of feed, on a pair-gain basis. In all mathematical fits, a well distinguishable "pubertal body growth spurt" at around 19 wk of age was found. About 40 to 70% of total growth within this phase consisted of growth of the reproductive tract (the ovary covered 19 to 35%, the oviduct 15 to 23%, and the uterus 7 to 11% of total growth). Age at maximum gain of the pubertal body growth spurt was 20.1 wk for lysine-restricted pullets and 19.6 wk for feed-restricted pullets. This difference reflected differences in onset of lay (50% rate of lay) between lysine- and feed-restricted birds (22.3 and 21.6 wk, respectively). An interval of 14 to 15 d existed between maximum gain of the pubertal body growth spurt and onset of lay. It was suggested that the occurrence of the pubertal body growth spurt can serve as a predictor for subsequent onset of lay. Body composition at defined moments during the pubertal body growth spurt was calculated by interpolation from chemical analyses of Weeks 15, 18, 20, 22, and 24. Crude fat content in the body at start of the pubertal body growth spurt varied considerably between the feeding regimens (112 to 179 g). The fat-free body (consisting of CP, ash, and water) showed less variation between the treatments at this stage (807 to 870 g). It is concluded that a particular amount of fat-free tissue is critical in pullet development and may be required before sexual organ development starts.

Age Factors↗

PubMed1997

Discrimination of Listeria monocytogenes strains of serotype 4b by restriction enzyme analysis of chromosomal DNA.

Epidemiologically related cheese and environmental strains and epidemiologically unrelated strains of Listeria monocytogenes serotype 4b were examined by restriction enzyme analysis of chromosomal DNA with a total of 10 restriction enzymes. The DNA fingerprint patterns generated from each restriction enzyme digest of total DNA of all strains were classified. The restriction enzyme patterns of seven strains recovered from cheese and environmental samples in the same plant were identical to each other, but differed from those of seven epidemiologically unrelated strains. Two, originating from sporadic human patients, of eight epidemiologically unrelated strains exhibited the identical restriction enzyme patterns. Excepting these two strains, restriction enzyme analysis of the chromosomal DNA of L. monocytogenes serotype 4b can discriminate serologically indistinguishable strains.

Animals↗

PubMed1992

The frequency of alpha 2-adrenoceptor restriction fragment length polymorphisms in normotensive and hypertensive humans.

OBJECTIVE: To examine the frequency of distribution of allelic polymorphisms of the alpha 2-adrenoceptor gene in normotensive and hypertensive humans. DESIGN: The frequency of alpha 2-adrenoceptor genotypes was compared in the two groups using the chi 2-test. SETTING: The Midwest Hypertension Research Center Outpatient Clinic of Creighton University School of Medicine. STUDY PARTICIPANTS: History was taken from and physical examination performed on each of the 60 hypertensive and 47 normotensive adults. METHODS: DNA was extracted from leukocytes from each participants. Twenty restriction endonucleases were used and one restriction fragment length polymorphism (RFLP) was found using a 950-bp restriction fragment from the coding region of the human platelet alpha 2-adrenoceptor gene (ADRA2R) and Bsu36I restriction endonuclease. This probe and Bsu36I restriction endonuclease, in addition to another restriction endonuclease (Dra I), were then used in the study. RESULTS: Three genotype patterns were found. Homozygotes for the Bsu36I RFLP have either a unique 12-kb or a unique 5.8-kb band. Heterozygotes have both bands. The frequency of this alpha 2-adrenoceptor RFLP was calculated. In hypertensives the frequencies of the 12- and 5.8-kb alleles were 0.52 and 0.48, compared with 0.45 and 0.55, respectively, in normotensive, a difference that was not statistically significant. CONCLUSIONS: The frequency of the Bsu36I RFLP involving an alpha 2-adrenoceptor gene in hypertensives did not differ significantly from that in normotensives. A genetic linkage study is now under way to test for an association of the Bsu36I RFLP of the alpha 2-adrenoceptor gene with essential hypertension in families.

Adult↗

PubMed2004

Tissue-specific effect of refeeding after short- and long-term caloric restriction on malic enzyme gene expression in rat tissues.

Restricting food intake to a level below that consumed voluntarily (85%, 70% and 50% of the ad libitum energy intake for 3 or 30 days) and re-feeding ad libitum for 48 h results in an increase of malic enzyme (ME) gene expression in rat white adipose tissue. The increase of ME gene expression was much more pronounced in rats maintained on restricted diet for 30 days than for 3 days. The changes in ME gene expression resembled the changes in the content of SREBP-1 in white adipose tissue. A similar increase of serum insulin concentration was observed in all groups at different degrees of caloric restriction and refed ad libitum for 48 h. Caloric restriction and refeeding caused on increase of ME activity also in brown adipose tissue (BAT) and liver. However, in liver a significant increase of ME activity was found only in rats maintained on the restricted diet for 30 days. No significant changes after caloric restriction and refeeding were found in heart, skeletal muscle, kidney cortex, and brain. These data indicate that the increase of ME gene expression after caloric restriction/refeeding occurs only in lipogenic tissues. Thus, one can conclude that caloric restriction/refeeding increases the enzymatic capacity for fatty acid biosynthesis.

Adipose Tissue↗

PubMed1991

Potential deleterious impact of dietary salt restriction on cardiovascular risk factors.

Excessive intake of dietary salt is thought to promote hypertension in Western societies, and some have recommended salt restriction for the general population. While such restriction is thought to be innocuous, few studies have examined the impact of dietary salt on cardiovascular risk factors other than blood pressure. In a randomized, placebo-controlled, doubly blinded comparison of one week periods of 20 vs. 208 mEq/d NaCl intake in 27 hypertensives and normotensives, we found that salt restriction had no significant effect on blood pressure (p = 0.45) and a generally adverse impact on risk factors for cardiovascular disease. Stringent, short-term dietary salt restriction caused increases in total and low-density lipoprotein cholesterol that were of borderline significance (p = 0.07). These lipid effects probably resulted from plasma volume contraction, as they were coincident with significant rises in hemoglobin (p = 0.01), hematocrit (p less than 0.001), total protein (p less than 0.01) and albumin (p = 0.01); such changes may act together to increase whole-blood viscosity. In addition, plasma norepinephrine (p = 0.02), fasting plasma insulin (p = 0.02) and glucose-to-insulin ratio (p = 0.01) increased during salt restriction. The potentially adverse impact of dietary salt restriction on the risk factor profile for cardiovascular disease suggests that further studies are necessary before a reduction in dietary salt intake can be prescribed for the general population.

Adult↗

PubMed1990

[Detection of aquatic microorganisms from the Black Sea--producers of restriction endonucleases].

300 clones of microorganisms isolated at different stations and from different depths in the Black Sea were screened for restriction endonucleases production. The production of restriction endonucleases was found in 17 clones screened. Three of them were identified to be Alteromonas haloplanktis B1. Restriction endonuclease AhaB1 is an isoshizomer of Sau961. An identified Alteromonas haloplanktis clone B8 produces AhaB8I restriction endonuclease the prototype to which is KpnI. Of the clones isolated three are Moraxella species B4 producing MapB4I restriction endonuclease analogous to BanI, three are Bacillus species producing BspB2I and one is Micrococcus lylae 113 producing Mly1131 analogue of NarI, six Moraxella species B6 produce MspB6I. The isolated producer strains may be used for isolation of above mentioned restriction endonucleases.

Bacteria↗

PubMed1990

Characterization of human centromeric regions using restriction enzyme banding, alphoid DNA and structural alterations.

Studies of banding induced by restriction enzymes may provide insight into banding mechanisms and chromosome structure. We examined whether or not the sizes of chromosome-specific alphoid DNA fragments created by digestion with various restriction enzymes relate to the presence or absence of C-like bands produced by these same enzymes. We sized alphoid DNA fragments from five different chromosomes, digested with each of six different restriction enzymes. There was no obvious correlation between the length of alphoid restriction fragments at specific human centromeric regions and the production of C-like bands. We used the enzyme AluI and traditional staining (CBG) techniques to band centromeres with conformational alterations. These included dicentric chromosomes, chromosomes from a patient with Roberts syndrome, and 5-azacytidine-treated prometaphase chromosomes. In all cases bands produced by AluI resembled CBG banding. We found that markedly decondensed portions of centromeric regions induced by 5-azacytidine did not band. Our studies demonstrate that restriction endonuclease C-like banding is not strictly related to the presence of restriction sites in alphoid DNA, and the condensed chromatin conformation at the centromeric region may play a role in banding.

Azure Stains↗

PubMed1989

Restriction fragment length polymorphism analysis with a cross-reactive HLA class II DR-beta gene probe for the detection of engraftment of MHC-mismatched marrow in the rhesus monkey.

Our interest in MHC-mismatched allogeneic bone marrow transplantation (BMT) in the rhesus monkey prompted us to investigate restriction fragment length polymorphism analysis as a means for detecting lymphohematopoietic chimerism in the primate. A human MHC (HLA) class II DR beta gene cDNA probe was tested on rhesus peripheral blood mononuclear cell DNA digested with any of three restriction enzymes. We found that (1) the human DR beta probe hybridized to as many as 15 restriction fragments per rhesus DNA sample, suggesting cross-hybridization at more than one locus of rhesus MHC class II beta genes; (2) restriction fragment length polymorphisms were common among outbred monkeys as a result of class II beta gene polymorphisms and would be sufficient for chimerism detection in the majority of random pairs of outbred monkeys utilizing only a single restriction enzyme (Bgl II); and (3) sensitivity (5-10% chimerism) was comparable to that reported for restriction fragment length polymorphism assays utilizing non-MHC probes in clinical HLA-identical BMT. Utility of the assay was demonstrated in a preliminary series of experiments in rhesus monkeys conditioned with mixed T cell-depleted MHC-mismatched allogeneic plus T cell-depleted autologous BMT with or without cardiac allograft implantation.

Animals↗