Decelerated growth and longevity in men

Severe dietary restriction delays the physical development of rodents and leads to adult animals of reduced body size but significantly increased life expectancy. We tried to find a similar relationship in human populations using demographical and statistical methods. We show for the total Spanish male population that the mean adult body height reliably reflects the regional living and nutritional conditions. This relation does not only hold for todays socioeconomic data but can also be reproduced using data on family income in the mid 19th century. We calculated the mean height of young men liable to the military service around 1860 and determined their longevity retrospectively using posterior census data. This was done separately for all the Spanish provinces. The linear regression between both parameters manifests a statistically highly significant relationship: the smaller the mean height at age 18 in a province, the higher the chance for people living there to reach high chronological ages. Migrational movements, selection, mortality due to epidemics or unreliability of the population censuses can be largely ruled out as explications for the described correlation. Furthermore, we determined the secular growth trend in Spain for the last 130 years. From 1860 to 1920 the mean height increased by 2.7 cm, from 1920 to 1987 by another 9.8 cm. Since 1950 the trend is above 2 cm per decade country-wide. From 1974 onwards it amounts to 2.89 +/- 0.17. Such high values were worldwide looked upon as isolated cases found only in geographically and socially isolated population subgroups during very limited periods.

Regulation of growth and tumorigenicity of breast cancer cells by the low molecular weight GTPase Rad and nm23

Rad is the prototypic member of a family of novel Ras-related GTPases that is normally expressed in heart, skeletal muscle, and lung and that has been shown to exhibit a novel form of bi-directional interaction with the nm23 metastasis suppressor. In the present study, we have investigated the expression of Rad in normal and neoplastic breast tissues by Western blot and immunohistochemistry and the functional effect of altered Rad expression in breast cancer cell lines. We found that, although Rad is frequently expressed in normal breast tissue (23/30 Rad+ve), expression is usually lost in adjacent invasive carcinoma (8/30 Rad+ve; P < 0.0001). However, where Rad expression persists in a small proportion of tumors, it is associated with higher grade, larger size, and extensive axillary nodal involvement (n = 48; P = 0.035, P = 0.016, P = 0.022, respectively). Furthermore, Rad is also highly expressed in a breast cancer cell line with high tumorigenic and metastatic potential (MDA-MB231). To further examine the role of Rad in breast cancer, we stably transfected a Rad-ve breast cancer cell line (MDA-MB435). We observed an increase in growth and marked increased colony formation in soft agar in vitro (P < 0.05) and an increase in tumor growth rate in nude mice (P < 0.05). Moreover, coexpression of nm23 with wild-type Rad inhibited the effect of Rad on growth of these cells in culture and markedly inhibited tumor growth in vivo. Additional transfection studies with mutated Rad cDNAs revealed that the growth-promoting effects of Rad appeared to be mediated through its NH2- and COOH-terminal regions, rather than its GTPase domain, and might involve acceleration of cell cycle transition. These findings suggest that Rad may act as an oncogenic protein in breast tissues and demonstrate a potential mechanism by which interaction between Rad and nm23 may regulate growth and tumorigenicity of breast cancer.

The branch point enzyme of the mevalonate pathway for protein prenylation is overexpressed in the ob/ob mouse and induced by adipogenesis

We have recently reported that skeletal muscle of the ob/ob mouse, an animal model of genetic obesity with extreme insulin resistance, exhibits alterations in the expression of multiple genes. Analysis and cloning of a full-length cDNA of one of the overexpressed mRNAs revealed a 300-amino-acid protein that could be identified as the mouse geranylgeranyl diphosphate synthase (GGPP synthase) based on its homology to proteins cloned from yeast and fungus. GGPP synthase catalyzes the synthesis of all-trans-geranylgeranyl diphosphate (GGPP), an isoprenoid used for protein isoprenylation in animal cells, and is a branch point enzyme in the mevalonic acid pathway. Three mRNAs for GGPP synthase of 4.3, 3.2, and 1.7 kb were detected in Northern blot analysis. Western blot analysis of tissue homogenates using specific antipeptide antibodies revealed a single band of 34.8 kDa. Expression level of this protein in different tissues correlated with expression of the 4.3- and 3.2-kb mRNAs. GGPP synthase mRNA expression was increased 5- to 20-fold in skeletal muscle, liver, and fat of ob/ob mice by Northern blot analysis. Western blot analysis also showed a twofold overexpression of the protein in muscle and fat but not in liver, where the dominant isoform is encoded by the 1.7-kb mRNA. Differentiation of 3T3-L1 fibroblasts into adipocytes induced GGPP synthase expression more than 20-fold. Using the immunoprecipitated protein, we found that mammalian GGPP synthase synthesizes not only GGPP but also its metabolic precursor farnesyl diphosphate. Thus, the expression of GGPP synthase is regulated in multiple tissues in obesity and is induced during adipocyte differentiation. Altered regulation in the synthesis of isoprenoids for protein prenylation in obesity might be a factor determining the ability of the cells to respond to hormonal stimulation requiring both Ras-related small GTPases and trimeric G protein-coupled receptors.

Functional interactions between melanin-concentrating hormone, neuropeptide Y, and anorectic neuropeptides in the rat hypothalamus

A growing body of evidence indicates that a number of peptides expressed in the mammalian hypothalamus are involved in the regulation of food intake and energy balance. Among these, melanin-concentrating hormone (MCH) and neuropeptide Y (NPY) are potent appetite stimulants, whereas alpha-melanocyte-stimulating hormone (alpha-MSH), neurotensin, and glucagon-like peptide (GLP)-1(7-36) amide have appetite-suppressing properties. However, the functional interactions between pathways involving these neuropeptides remain incompletely understood. In the current study, we describe the functional interactions between orexigenic (appetite-stimulating: MCH and NPY) and anorectic (appetite-suppressing: alpha-MSH, neurotensin, and GLP-1) peptides after intracerebroventricular (i.c.v.) administration in the rat. The i.c.v. administration of GLP-1 completely prevents the orexigenic effects of both MCH and NPY. However, i.c.v. administration of alpha-MSH prevents only the orexigenic effect of MCH, as we have previously shown, but does not prevent the effect of NPY on food intake. Similarly, i.c.v. administration of neurotensin prevents only the orexigenic effect of MCH, but does not prevent the appetite-stimulating effect of NPY. Thus, our study suggests that the functional interactions between these neuropeptides are specific, although the underlying mechanisms are as yet unexplored.

Alterations in skeletal muscle gene expression of ob/ob mice by mRNA differential display

To identify molecules that contribute to insulin resistance, we compared the patterns of gene expression in skeletal muscle of the obese ob/ob mouse, a genetic model of obesity and severe insulin resistance, with that of its thin littermate (ob/+) using the mRNA differential display method. From about 9,000 cDNAs displayed, we found 12 differentially expressed in ob/ob mice skeletal muscle that could be recovered from the differential display gels and confirmed by Northern blot analysis and sequenced. Eight mRNAs were overexpressed in ob/ob muscle: Id2 (a negative regulator of the basic helix-loop-helix family of transcription factors), fast skeletal muscle troponin T, ribosomal protein L3, the integral protein of the peroxisomal membrane 22PMP, the mammalian homolog of geranylgeranyl pyrophosphate synthase, an mRNA related to phosphatidylinositol-glycan-specific phospholipase D, and two unknown mRNAs. The level of overexpression of these mRNAs in skeletal muscle varied from a 500% increase to as little as a 25% increase. Two mRNAs were underexpressed 20-35%, including the f-subunit of mitochondrial ATP synthase and a retrovirus-related DNA. Two proteins with multiple transcripts, skeletal muscle alpha-tropomyosin and one for a repetitive sequence, showed a change in mRNA pattern of expression in the muscle of the ob/ob mouse. Because the primary genetic defect in the ob/ob mouse is known to be in the leptin gene, these data indicate how acquired alterations in gene expression of multiple classes of proteins may play a role in the complex pathogenesis of insulin resistance in obesity and diabetes.

Genetics of non-insulin-dependent (type-II) diabetes mellitus

Both genetic and environmental factors contribute to the etiology of non-insulin-dependent diabetes. The genetic component is heterogeneous and in some patients is probably complex, involving multiple genes. Specific genetic defects have been identified for rate monogenic forms of NIDDM: maturity-onset diabetes of the young, or MODY (which is due to glucokinase mutations in about 40% of families), syndromes of extreme insulin resistance (which often involve the insulin receptor), and diabetes-deafness syndromes (with defects in mitochondrial genes). In contrast, the genes involved in common forms of NIDDM are still uncertain. Mutations have been extensively searched in genes regulating insulin signaling and secretion. Some evidence of involvement has been produced for insulin-receptor substrate-1, glycogen synthase, the glucagon receptor, a ras-related protein (Rad), histocompatibility antigens, PC-1, and fatty acid binding protein, but the contributions of these genes to NIDDM is probably small. Other candidate genes (e.g. insulin, insulin receptor, glucose transporters) have been excluded as major diabetogenes. New insights are expected in the near future from the systematic scanning of the genome for linkage with NIDDM.

Increase in insulin secretion with age: its clinical importance in evaluating abnormal secretions focused on diabetes type II and obesity

The urinary C-peptide excretion was measured in a healthy standardized population sample of 160 subjects from 20 to 90 years of age, homogeneously distributed by age and sex. Urinary C-peptide excretion corresponded to 7% of the total amount released. The daily C-peptide excretion was 61.23 +/- 2.2 (S.E.) microg in the whole sample which corresponds to 41.9 +/- 1.5 IU of insulin secreted/day (I(CP)d), without sex differences. There is an increase of the I(CP)d value from the young to the healthy middle-aged person, but when the results were corrected for standard amounts of excreted creatinine (1 g) and urea (22 g) the age-dependent increase is to be observed during the whole adult life span. Assuming that cross-sectionally observed data are representative of the individual changes, it is concluded that age alone increases insulin secretion. The results which may be useful as reference values for clinical application were as follows: (A) in 5 diabetes type II patients in which the I(CP)d value was measured several times a week, the intraindividual variation coefficient was 10.9 +/- 7.2%;(B) in a sample of 47 type II diabetic patients of both sexes, between 51 and 70 years of age, a clear correlation was found between I(CP)d and the results of the glucagon stimulation test, mainly regarding the relationship between I(CP)d and the planimetrically measured area under the curve (r = 0.7, P < 0.0001); (C) in 7 obese non-diabetic individuals of similar ages the influence of the hypocaloric diet on the I(CP)d value was more evident than the use of C-peptide blood determinations before or after glucagon. Finally, the I(CP)d values of type II diabetes patients with insulin requirement (n = 27) were significantly lower than in the healthy control group (31.1 +/- 24.0 vs. 45.0 +/- 20.4), while diabetic patients without insulin requirement showed significantly higher values (73.0 +/- 33.0) (n = 27). These clinical studies primarily focused on the physiology of human ageing justify the measurement of C-peptide urinary excretion for evaluating daily insulin secretion in patients with type II diabetes.

GLP-1(7-36)amide binding in skeletal muscle membranes from streptozotocin diabetic rats

A higher specific binding of GLP-1(7-36)amide is found in skeletal muscle plasma membranes from adult streptozotocin (STZ)-treated rats (insulin-dependent diabetes mellitus model) and from neonatal STZ-treated rats (non insulin-dependent diabetes mellitus model), as compared to that in normal controls; no apparent change in the affinity was observed, that indicating the presence in both diabetic models of an increased number of high affinity binding sites for the peptide. The maximal specific GLP-1(7-16)amide binding in the non insulin-dependent diabetes mellitus model was found to be significantly higher than that in the insulin-dependent diabetes mellitus model. As GLP-1(7-36)amide exerts a glycogenic effect in the rat skeletal muscle, the present data suggest that the action of the peptide in the muscle glucose metabolism may be increased in states of insulin deficiency accompanied or not by insulin resistance.

Are anthropometric changes in healthy adults caused by modifications in dietary habits or by aging?

The aim of this work was to investigate to what extent age-dependent anthropometric changes are causally related to changes in dietary habits. In a randomly obtained sample of 246 healthy adults in the age range of 20-90 years from a well-defined agrarian population, the intake of proteins, fat and carbohydrates in males decreases with age (r = -0.65, p < 0.001; r = -0.65, p < 0.001; r = -0.5, p < 0.01, respectively), but in females it remains unaltered (e.g. the mean +/- SD daily protein intake in young adult females is 74 +/- 31 vs. 71 +/- 11 g in individuals over 80); in males it decreases from 140 +/- 34 to 71 +/- 13 g. On the contrary, in both sexes the muscle-mass-related measurements decrease (r = -0.45, p < 0.001; vs. r = -0.41, p < 0.001; mean values of the quotient lean body mass with body length in young adult females and males were 41.9 +/- 4.4 and 52.7 +/- 5.9 vs. 35.0 +/- 3.1 and 43.2 +/- 5.0, respectively, in individuals over 80, p < 0.001 in both sexes). From 35 onwards, the daily urea excretion-as a marker of the protein degradation rate-declines significantly with age, but without a clear correlation to the protein intake (r = 0.38), as occurs during young adulthood (r = 0.63). Furthermore, body fat content tends to increase with age, but the differences are statistically significant only in males of very advanced age (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of insulin secretion and potentiation of glibenclamide-induced insulin release by the dimethyl ester of glutamic acid in anaesthetized rats

The dimethyl ester of L-glutamic acid (GME) stimulates insulin release in isolated pancreatic islets and may represent a novel experimental tool in the study of non-insulin-dependent diabetes. In the present study, GME was found both to stimulate insulin secretion and to augment glibenclamide-stimulated insulin release in normal anaesthetized rats. A comparable hierarchy in the magnitude of the secretory response to GME and/or glibenclamide was found in control rats and animals injected with streptozotocin during the neonatal period. In the latter animals, however, the B-cell secretory response was invariably lower than in control animals. It is proposed that GME represents a novel tool to bypass anomalies of glucose transport and metabolism in the beta cell and, hence, to stimulate insulin release and enhance the insulinotropic action of hypoglycaemic sulphonylurea in animal models of non-insulin-dependent diabetes.

Impaired in vivo insulin secretion in response to non-glucidic secretagogues in adult rats after neonatal streptozotocin

In the perfused pancreas of adult rats that were injected with streptozotocin (STZ) during the neonatal period, the release of insulin caused by glucose is more severely affected than that evoked by other secretagogues. We have now examined whether a comparable situation prevails in vivo. In anesthetised rats, the 0-10 min plasma insulin incremental area recorded after intravenous glucose administration (2.8 mumol/g body wt) was severely decreased in STZ rats, with a K value for glucose utilization of 1.9 +/- 0.2 x 10(-2)/min, as compared with control rats, with a K value of 4.4 +/- 0.4 x 10(-2)/min. At the 2nd min of the test, the plasma insulin increment was about 5 times lower in STZ than control rats. After glibenclamide administration (0.1 nmol/g body wt), the insulin incremental area was 3 times lower in STZ than control rats. Relative to the post-prandial readings, the plasma glucose concentration was decreased to the same extent, however, in control and STZ rats injected with glibenclamide. The secretory response to succinic acid methyl ester (SAM; 1.0 mumol/g body wt) was virtually abolished in the STZ rats. In the latter animals, SAM also failed to enhance the hypoglycemic action of glibenclamide in contrast to the situation found in control rats. Iterative intraperitoneal administration of SAM (1.0 mumol/g body wt) thrice daily for 7-10 days failed to improve significantly the insulin secretory response to glucose or glibenclamide, whether in control or STZ rats. These findings indicate that the altered metabolism of glucose in the B cell of STZ rats coincides with an impaired secretory response to glibenclamide and SAM, as possibly attributable, in part at least, to a loss of the modulating action of glucose upon the secretory response to the hypoglycemic sulfonylurea and succinate ester.

In vivo stimulation of insulin release by succinic acid methyl esters

Both the monomethyl and dimethyl esters of succinic acid, administered intravenously to fasted and anesthetized rats, caused a rapid increase in plasma insulin. A positive insulin secretory response to succinic acid monomethyl ester was also observed after intraperitoneal injection to fed and conscious rats. On a molar basis, stimulation of the insulin release, evoked by succinic acid esters, represented about twice that caused by D-glucose. It is speculated that succinic acid esters may be efficient insulin secretagogues even in those models of noninsulin-dependent diabetes characterized by a site-specific defect in the transport of D-glucose or in the early steps of its catabolism in the pancreatic B-cell.

Incidence and prevalence of ulcerative colitis and Crohn's disease in urban and rural areas of Spain from 1981 to 1988

We retrospectively investigated the annual incidence and prevalence of inflammatory bowel disease (IBD) from 1981 to 1988 in an urban and a rural area of central Spain. Two hundred and eighty-one patients presented with IBD; 193 ulcerative colitis (UC) and 88 Crohn's disease (CD) (prevalence 43.4/100,000 and 19.8/100,000, respectively). Of these patients, 168 were diagnosed for the first time during the study period. One hundred and eleven UC and 57 CD (incidence 3.16/100,000 and 1.61/100,000 respectively). Within the urban area, the UC incidence was 3.15/100,000 and the CD 1.87/100,000. In the rural area, the incidence for the UC was 3.25/100,000 and 0.86/100,000 for the CD. No sex differences were found. The incidence rates have increased significantly (p < 0.05) for CD in the study period. However, for UC rates did not change. During 1986-1988, the patient's age at the time of diagnosis was significantly lower than that of 1981-1983 (p < 0.05).

Assessment of the age of atherosclerosis risk in population studies using a two factorial mathematical model

The risk of atherosclerosis was assessed using a mathematical model of competition between LDL and HDL on 365 randomly selected persons. The results speak for the fact that the risk falls between the ages of 30 and 40 years for males, and 40 and 50 years for females. We are of the opinion that our procedure may be valid for sex comparison studies attempting to objectify the prevalence of atherosclerosis in population studies.

Measuring human aging using a two-compartmental mathematical model and the vitality concept

We calculated a theoretical vitality function as a reference curve, based on experimental results from 226 healthy individuals. This can be used to assess biological aging rates of geographically separate human populations. Only six parameters were used to assess vitality. Each parameter is associated with one of the two physiological compartments. We assume that one compartment keeps the system stable and the other maintains system fidelity. The results permit us to compare vitality curves within populations as well as to determine the age at which maximum vitality appears in each population. The differences between biological and chronological ages in each population and possible etiological interpretations are discussed. This mathematical model can be useful as a method to measure differences in aging rates and effects of aging in several human populations.

[Changes with age in adiposity and lean body mass in a healthy Spanish population]

The reduction in muscular mass with age is well-known, and thus in order to obtain reference values, the behaviour of the LBM and corporal adiposity (FM) in a standard population was studied. Of a total of 217 patients considered a priori as healthy, 172 were selected following a strict application of criteria based on clinical examination, haematological analysis and biochemical parameters, as well as hormone concentrations, aimed showed urinary elimination of creatinine (Cro) of between (+ - DE) within the theoretical level for their weight and age. In this standard population, the behaviour of the LBM and FM was studied depending on age, using for this purpose creatinine at 24 hours, weight and size, and different calculation procedures. The reduction in LBM showed a better correlation with age when calculated based on Cro (r = 0.47; p < 0.01) than on height (r = -0.27; p < 0.01). The age correlation was similar for both sexes (women: r = -0.60; men: r = -0.65) and reduction in LBM started to be considerable from the fifth decade and could be calculated from the regression equation LBM = 64.6 - 0.00069. age (days). At the same time as this reduction in LBM, there was an increase in FM (p < 0.0001). Our results show that the reduction of LBM and increase in FM with age in a healthy Spanish population is similar to other foreign studies published. It is preferable to correct the LBM with age using Cro, which can be calculated using the above-mentioned linear regression equation, regardless of sex.