Hypothalamic and medullary GABAA and GABAB-ergic systems differently regulate sympathetic and cardiovascular systems

1. To determine whether hypothalamic and medullary GABA (gamma-aminobutyric acid)B stimulation would affect the sympathetic and cardiovascular activities, and to determine whether these effects would be altered in hypertension, baclofen (a GABAB agonist) was injected into a hypothalamic pressor area (ventromedial hypothalamus, VMH), a depressor area (anterior hypothalamus, AH), or a nucleus tractus solitarius (NTS) in normotensive and spontaneously hypertensive rats (SHR). 2. Intracerebroventricular (ICV) injections of a GABAA agonist (muscimol, 1 mu g) decreased blood pressure (BP) and heart rate (HR). ICV injections of baclofen (2 mu g) elicited biphasic depressor and pressor effects, and these effects were abolished by a pretreatment with saclofen (GABAB antagonist, 100 mu g, icv). 3. Muscimol (400 ng) and baclofen (800 ng) injected into VMH decreased sympathetic nerve activity (SNA), BP and HR to almost similar levels, while saclofen injected into VMH increased HR without affecting BP levels. 4. The same dose of baclofen injected into AH increased BP, but muscimol (AH) did not alter BP. 5. Both muscimol and baclofen injected into NTS increased BP, but its magnitude was larger in baclofen injections. 6. Depressor and sympatho-inhibitory effects of baclofen (VMH) in SHR were larger than those in normotensive Wistar-Kyoto (WKY) rats, while pressor responses elicited by baclofen (AH) did not differ between SHR and WKY. 7. In summary, GABA reduces SNA, BP and HR through both GABAA and GABAB receptors in VMH. In addition, the GABAB system acts on AH and NTS to further regulate the cardiovascular activities. In SHR, GABAB-ergic dysfunction in VMH but not in AH might contribute to the development of hypertension.

Functional alteration of the GABAB receptor in the brain of spontaneously hypertensive rats

1. We studied the ontogenetic development of GABAB receptors and their coupling to cyclic AMP formation in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rat brains. GABAB receptor binding to various brain regions was compared in age-matched SHR and WKY rats. 2. The specific [3H]-GABA binding to the posterior hypothalamus (PH) was significantly lower in not only 4 week old (normotensive) but also 11 week old (hypertensive) SHR, when compared with age-matched WKY. 3. Moreover, GABAB receptor agonists (baclofen and DN-2327)-induced suppression of adenylate cyclase activity also showed a decrease in 4 week old and 11 week old SHR PH. 4. We concluded that the number and the functional responsiveness of GABAB receptors in rat brains decrease in SHR, preceding blood pressure elevation. The activity of GABABergic mechanisms may be different in the brains of SHR and WKY rats.

Role of baroreflex and central alpha2-adrenergic receptor systems in the diurnal variation of blood pressure and heart rate in normotensive and hypertensive rats

1. To elucidate whether baroreflex could contribute to manifest the diurnal blood pressure variations (DBPV) in normotension and hypertension, DBPV were recorded continuously via a femoral artery in awake normotensive (NT) rats and spontaneously hypertensive rats (SHR) with and without sinoaortic denervation (SAD). To determine the role of central alpha2-adrenergic receptor system in DBPV in hypertension, guanabentz (0.5-1.0 mu g/kg per min) was infused in SHR. 2. There were no differences in mean arterial pressure (MAP) variability (SD) of MAP of 24 h (MAP -- SD/MAP) and SD of 24 h heart rate (HR -- SD/HR) between SHR and NT. SAD did not elevate MAP and HR in both SHR and NT. 3. However, in SAD rats, MAP -- SD/MAP was significantly greater than those in sham-operated rats in both SHR and NT, while MAP -- SD/MAP and HR -- SD/HR did not show any difference between the two groups even after SAD. On the other hand, SAD did not augment HR -- SD/HR in either strain. 4. During guanabentz infusion, MAP was significantly lowered in sham-operated and SAD -- SHR. Moreover, MAP -- SD/MAP was significantly reduced in sham-operated, but it was not in SAD -- SHR. 5. These findings suggest that baroreflex could suppress tonically the diurnal change of blood pressure in NT and SHR. The regulation of diurnal blood pressure by baroreflex via a central alpha-adrenergic receptor system may be altered in SHR.

Further characterization of the receptor mechanism involved in the antidysrhythmic effect of dexmedetomidine on halothane/epinephrine dysrhythmias in dogs

BACKGROUND

alpha 2 Adrenoceptors in the central nervous system mediate various physiologic processes, including cardiovascular control. Recently, some of these actions have been reported to be mediated by a nonadrenergic receptor, namely an imidazoline receptor. The authors previously reported that dexmedetomidine, a selective alpha 2 agonist, prevents the genesis of halothane-epinephrine dysrhythmias through a central mechanism. Because dexmedetomidine also binds to imidazoline receptors, we performed the current study to examine the precise receptor mechanism involved in the antidysrhythmic property of dexmedetomidine.

METHODS

Adult mongrel dogs were anesthetized with halothane (1.3%) and monitored continuously for systemic arterial pressure and premature ventricular contractions. The dysrhythmogenic dose of epinephrine was defined as the smallest dose producing four or more premature ventricular contractions within 15-s period. We examined the antidysrhythmic action of dexmedetomidine in the presence of two kinds of alpha 2 antagonists, that is, agents that label imidazoline receptors and exert a pharmacologic action through imidazoline receptors (idazoxan and atipamezole) and agents that are nonimidazoline compounds and are lacking in pharmacologic action through imidazoline receptors (rauwolscine and L-659,066). They were given cerebroventricularly.

RESULTS

Idazoxan and atipamezole significantly inhibited the antidysrhythmic action of dexmedetomidine, whereas rauwolscine and L-659,066 did not.

CONCLUSIONS

Because alpha 2 antagonists having imidazoline or imidazole structures inhibited the antidysrhythmic action of dexmedetomidine, and the inhibition produced by the non-imidazoline alpha 2 antagonists was not significant, imidazoline receptors in the central nervous system are more responsible for the antidysrhythmic action of dexmedetomidine than are alpha 2 adrenoceptors.

Altered cardiovascular responses to purinergic A2 stimulation in the nucleus tractus solitarius of spontaneously hypertensive rats

OBJECTIVE

To investigate the cardiovascular effects of adenosine A2 receptor stimulation in the nucleus tractus solitarius and whether these effects are altered in hypertension.

DESIGN AND METHODS

Ten- or 11-week-old spontaneously hypertensive rats (SHR) or Wistar-Kyoto (WKY) rats were anaesthetized with urethane. Adenosine (100 ng) or adenosine A2 agonist (2-octynyladenosine, 5 ng) were micro-injected (50 nl) into the nucleus tractus solitarius. Blood pressure and heart rate were measured from a femoral artery. Sympathetic nerve activity was recorded from the abdominal splanchnic nerve.

RESULTS

Blood pressure, heart rate and sympathetic nerve activity were consistently decreased after the micro-injection of adenosine into normotensive rats. Changes from the baseline in blood pressure, heart rate and sympathetic nerve activity were significantly smaller in SHR than in WKY rats (blood pressure: SHR -5.6 +/- 2.1% versus WKY rats -20.0 +/- 2.1%; heart rate: SHR -5.4 +/- 0.88% versus WKY rats -9.2 +/- 2.3%; sympathetic nerve activity: SHR -5.5 +/- 1.1% versus WKY rats -21 +/- 2.8%). Micro-injection of an A2 agonist into the nucleus tractus solitarius also decreased blood pressure and heart rate, and those responses were not inhibited by pretreatment with an adenosine A1-specific antagonist. The response induced by micro-injection of A2 agonist into the nucleus tractus solitarius was significantly smaller in SHR than in WKY rats, whereas the changes in heart rate did not differ statistically (blood pressure: -23.4 +/- 4.7% versus -10.8 +/- 2.1%; heart rate: -12.1 +/- 1.2% versus -13.6 +/- 2.1%).

CONCLUSION

The present results suggest that stimulation of adenosine A2 receptors in the nucleus tractus solitarius decreases both blood pressure and inhibitory sympathetic nerve activity and that those inhibitory responses to adenosine in the nucleus tractus solitarius are deranged in SHR.

Cloning, tissue distribution, and intrarenal localization of ClC chloride channels in human kidney

Two kidney-specific chloride channels, ClC-K1 and ClC-K2, have been isolated from rat kidney. In the present study, we sought to isolate human homologue of rat ClC-K2 chloride channel that was present in the thick ascending limb of Henle's loop and collecting ducts. Human kidney cDNA library was screened with the whole rat ClC-K2 cDNA probe. Two highly homologous but not identical cDNAs were isolated and sequenced. Northern analysis showed that both clones were expressed only in kidney among various human tissues, demonstrating that kidney-specific ClC family members were also present in human kidney. Because both clones had almost the same nucleotide identity (approximately 80%) with rat ClC-K2, we could not determine by sequence alone which human clone corresponded to rat ClC-K2. Accordingly, we performed reverse transcription PCR using dissected human nephron segments and identified the site of expression of each clone in human nephron segments. One clone was only expressed in the thin limb of Henle's loop and the other was expressed in glomeruli, proximal tubules, and collecting ducts. We identified the latter clone as human ClC-K2 based on the localization of rat ClC-K1 and ClC-K2. Identification of human ClC-K2 clone will be of help in understanding the genetic involvement of chloride channel in disorders of chloride transport such as Bartter's syndrome.

Two consecutive nucleotide substitutions resulting in the T3 receptor beta gene resulting in an 11-amino acid truncation in a patient with generalized resistance to thyroid hormone

We identified unusual mutations in the T3 receptor (TR) beta gene in a 6-year-old Japanese girl with generalized resistance to thyroid hormone. Two consecutive base substitutions, T to A and C to A at nucleotide positions 1637 and 1638, respectively, changed the 451st codon coding for Phe(TTC) to stop codon (TAA), resulting in an 11-amino acid carboxyl(C)-terminus truncation. The patient was a heterozygote. Western blotting using an anti-TR antibody demonstrated the truncated receptor protein. The patient showed severe mental retardation (IQ41), disturbance in speech development, and attention deficit hyperactivity disorder. Thyroid functional status by clinical evaluation was considered within the normal range in spite of high serum thyroid hormone levels (T4 725.9 nmol/l, T3 12.7 nmol/l, FT4 166.0 pmol/l). TSH increased from 0.6 to 24 mU/L after TRH (150 micrograms) injection. TSH secretion as well as 123I-uptake was suppressed only partially by T3 (75 micrograms/day for a week). Close examination of thyroid functions and TR beta gene analysis were not possible in the family, except for paternal grandmother and one of her two sisters who showed no abnormality. The patient's truncated TR beta showed very low T3 binding activity (Ka = 0.1 x 10-10 M), transcriptional activity, and a very strong dominant negative effect. When co-expressed with wild-type TR beta at the molar ratio 1:1 in CV-1 cells, the mutant receptor inhibited the wild-type TR beta transcriptional activity by 74% at 10 nM T3. Even 1 microM T3 could not normalize these impaired functions.

[A case of adult pure yolk sac tumor of the testis achieving pathological complete response by chemotherapy]

We report a case of pure yolk sac tumor of the left testis in a 22-year-old male. He consulted a physician with left back pain and induration of his left scrotal content in December, 1992. Intravenous pyelography (IVP) revealed left hydronephrosis. Computerized tomography (CT) revealed para-aortic lymph node swelling and lung metastases. Left high inguinal orchiectomy was performed. Histopathological diagnosis was pure yolk sac tumor. After two courses of "COMPE" chemotherapy consisting of cisplatin, vincristine, methotrexate, peplomycin and etoposide, two courses of "high dose "COMPE" chemotherapy and three courses of "high dose COME" chemotherapy without peplomycin, he achieved a partial response (the regression rate of the pulmonary metastases and the retroperitoneal lymph node metastasis were 100% and 96.0% on CT, respectively) and the residual masses in the retroperitoneum were removed. Necrosis and xanthogranulomatous fibrosis were found in the resected material. The patient showed no evidence of disease two years after chemotherapy.

Changes in the sex ratio of stroke mortality in the period of 1955 through 1990

BACKGROUND AND PURPOSE

Stroke mortality worldwide has decreased in men and women in most industrialized countries, except in eastern European countries. The purpose of this study was to compare the sex ratio of stroke mortality between populations and over time. This approach may help to determine the factors influencing this ratio.

METHODS

The sex ratios (men to women) of stroke mortality between ages 55 to 64, 65 to 74, and 75 to 84 years from 27 populations between 1955 and the latest available year were analyzed using World Health Organization data. The relationship between log stroke mortality and age and the relationships between alcohol, animal fat, cigarette consumption, and urinary cation excretion and the sex ratio of stroke mortality were also analyzed.

RESULTS

The mean sex ratio of stroke mortality increased 50%, 34%, and 15% in the three age classes, respectively, over 35 years. Highly significant relationships of log stroke mortality with age exist, which vary between men and women and among countries. In general, stroke mortality changed in the same direction in both sexes but decreased earlier and more rapidly in women than in men. Alcohol consumption and urinary sodium excretion correlated positively and significantly with the sex ratio. The time trends of the sex ratio also correlated positively and significantly with the time trends of cigarette consumption. No relationship with animal fat consumption was found.

CONCLUSIONS

The sex ratio of stroke mortality is increasing with time and decreasing with age. Differences in lifestyle among countries and over the last three decades may contribute partially to these differences in sex ratio.

Role of prostaglandins E1, E2 and F2 alpha in the brain in interleukin 1 beta-induced adrenocorticotropin secretion in the rat

It is well known that interleukin (IL)-1 is a potent activator of the hypothalamo-pituitary-adrenal axis in the rat. Many studies have reported that prostaglandins (PGs), especially PGE2, in the brain may mediate the IL-1 stimulation of corticotropin-releasing hormone release, which then leads to adrenocorticotropin (ACTH) secretion. However, a general consensus has yet to emerge regarding whether PGE2 is the only or the most important PG in the brain mediating IL-1-induced ACTH secretion in the rat. To address this question, we examined the effect of intracerebroventricular (icv) administration of antisera against PGE1, PGE2 or PGF2 alpha, or normal rabbit serum on the ACTH response induced by an icv injection of IL-1 beta in the rat. Each antibody or normal rabbit serum (as the control) was given icv 15 min before an icv administration of human recombinant IL-1 beta (50 ng). IL-1 beta produced a significant rise in plasma ACTH levels, and this response was significantly suppressed by either of the three PG antibodies. Interestingly, the inhibitory effect of anti-PGE2 antibody seemed to be somewhat weaker than those of the other two antibodies. We conclude that not only PGE2 but also PGE1 and PGF2 alpha in the brain may mediate the IL-1 beta stimulation of ACTH secretion in the rat.

Lung preservation threshold in a compromised septic lung injury model

BACKGROUND

Discrepancy between clinical and research works in lung transplantation could be due to differences between compromised clinical donor lungs and intact research lungs. The purpose of this laboratory study was to produce compromised lungs to compare with normal ones.

METHODS

Sprague-Dawley rats were continuously infused with lipopolysaccharide (5 mg/kg) for 24 hours before organ harvest. Lungs were stored in University of Wisconsin solution at 4 degrees C for the following period: group 1: intact lungs, no storage (n = 12); group 2: septic lungs, no storage (n = 6); group 3: septic lungs for 6 hours (n = 5); and group 4: septic lungs for 12 hours (n = 5). All lungs were reperfused for 2 hours with venous blood using an isolated, pulsatile perfused lung system.

RESULTS

Experimental variables were comparable between groups 1, 2, and 3. All septic lungs stored for 12 hours (group 4) failed within 1 hour of perfusion.

CONCLUSIONS

These results indicate that compromised lungs with septic injury functioned at near control levels after 6 hours of preservation. Six hours may be a safe limit for human donor lungs, all of which are compromised in some way by the time of harvest.

Nutrition, latitude, and multiple sclerosis mortality: an ecologic study

An epidemiologic study has been performed on the relation between the mortality rates from multiple sclerosis for the period 1983-1989 obtained for 36 countries, dietary fat, and latitude. By stepwise multiple regression analysis, saturated fatty acids, animal fat, animal minus fish fat, and latitude correlated independently and positively with multiple sclerosis mortality (p < 0.01-0.001 for fat consumption, and p < 0.05-0.01 for latitude). The ratio of polyunsaturated fatty acids to saturated fatty acids (P/S ratio) and the ratio of unsaturated fatty acids (monounsaturated and polyunsaturated fatty acids) to saturated fatty acids (U/S ratio) correlated independently and negatively with multiple sclerosis mortality (p < 0.05-0.001). These findings support the hypothesis linking dietary fat intake and latitude to multiple sclerosis mortality.

Synthesis of carbocyclic analogues of the mannosyl trisaccharide: ether- and imino-linked methyl 3,6-bis(5a-carba-alpha-D-mannopyranosyl)-3,6-dideoxy-alpha-D-mannopyran osides

Carbocyclic analogues 2 and 3 of the "trimannosyl structure 1", methyl 3,6-bis(5a-carba-alpha-D-mannopyranosyl)-3,6-dideoxy-alpha-D-ma nnopyranosides bonded by way of respective ether and imino linkages, were synthesized. The ether 2 had no inhibitory activity against alpha-D-mannosidase; in contrast, the imino compound 3 was a mild inhibitor. Furthermore, the inhibitory activity of 4, related to 3 by introduction of unsaturation between C-5 and C-5a of the carba-sugar moieties, was shown to be somewhat greater.

[Radiological diagnosis of renal oncocytoma]

Eight patients (nine tumors) with histologically proven renal oncocytoma are presented. In all cases, differential diagnosis between renal oncocytoma and renal cell carcinoma could not be done on ultrasonography. On selective renal angiography, extended arteries surrounding the tumor margin was demonstrated in six of seven tumors without a spoke-wheel arterial supply. A sharp and smooth margin with capsule (lucent rim) could be found in five cases, and a spoke-wheel configuration of vessels could be seen in only two cases. A spoke-wheel pattern might be found with tumor growth. All tumors on computed tomography (CT scan) have a distinct margin, a smooth contour and a homogeneous appearance on contrast enhanced CT scan. The capsule and the presence of a central scar were clearly seen on T1 and T2 weighted images of magnetic resonance imaging (MRI). It is helpful to differentiate the oncocytoma from renal cell carcinoma. The modality of MRI may be useful in the preoperative diagnosis of oncocytoma.

Prevalence of hepatitis C virus and other blood-borne viruses in Pygmies and neighbouring Bantus in southern Cameroon

The prevalences of antibodies to hepatitis C virus (anti-HCV), human immunodeficiency virus (anti-HIV), human T lymphotrophic virus (anti-HTLV) and of hepatitis B surface antigen (HbsAg) were determined in 168 subjects aged 12 years and over (108 Pygmies, 60 Bantus) living in south Cameroon. In 167 subjects, we found an estimated minimal anti-HCV prevalence of 13%. The prevalence was significantly higher in Bantus (31.7%) than in Pygmies (11.1%) and increased with age in both groups, albeit more rapidly in Bantus. The overall prevalence of HBsAg was 7.2% and correlated with neither sex nor ethnic group. No association was found between anti-HCV and HbsAg prevalence rates. No subject was confirmed to be positive for HTLV or HIV. These findings confirm the high prevalence of HCV infection in south Cameroon and indicate that even secluded population groups are affected.

AVP inhibits EGF-stimulated MAP kinase cascade in Madin-Darby canine kidney cells

We investigated the effects of epidermal growth factor (EGF) and arginine vasopressin (AVP) on Raf-1-MAP kinase cascade, including Raf-1-kinase (Raf-1-K), MAP kinase kinase (MAPKK), MAP kinase (MAPK) and S6 kinase (S6K) in Madin-Darby canine kidney (MDCK) cells. In a dose-dependent manner (10(-10) M to 10(-6) M), EGF increased autophosphorylation of Raf-1-K and activated MAPKK, MAPK and S6K. Sequential activation of these kinases was indicated by their peak times of activation (Raf-1-K 5 min; MAPKK 10 min; MAPK 15 min; and S6K 30 min). AVP (10(-9) M to 10(-6) M) inhibited EGF-stimulated MAP kinase cascade. 8-Bromo-cyclic AMP (cAMP) could mimic the inhibitory effect of AVP on EGF-stimulated MAP kinase cascade. These results were confirmed using H-89, an inhibitor of protein kinase A (PKA) that blocked the effect of AVP on EGF-stimulated MAPK activity. We conclude that AVP inhibits EGF-stimulated Raf-1-K, MAPKK, MAPK, and S6K activity via cAMP in MDCK cells. Our results indicate that MAP kinase cascade may play an important role in integrating the effects of AVP and EGF on distal tubule function.

A case of cyclical Cushing's disease associated with corticosteroid-binding globulin deficiency: a rare pitfall in the diagnosis of Cushing's disease

We experienced an extremely unusual combination of Cushing's disease and corticosteroid-binding globulin (CBG) deficiency that has been reported in only one similar case to date. A 53-year-old woman presented at a medical clinic with clinical Cushing's disease. However, her plasma levels of adrenocorticotropin (ACTH) and cortisol were in the normal range. Six months later, during a second visit, a high urinary excretion of 17-hydroxycorticosteroids was found, but plasma ACTH and cortisol levels were normal again. Further investigation revealed a decreased CBG concentration. Free plasma cortisol levels were clearly elevated. Furthermore, the Cushing's disease of our patient was complicated by periodic secretion of ACTH and cortisol, with high or normal outputs of corticosteroids occurring alternately every 1-3 days, which explained the occasionally normal plasma ACTH and cortisol levels. A combination of a decreased serum CBG concentration and periodic secretion of ACTH can be an important pitfall in the diagnosis of Cushing's disease.

Functional properties of a mutant T3 receptor beta (R338W) identified in a subject with pituitary resistance to thyroid hormone

Previously, we identified a point mutation of the T3 receptor (TR) beta gene (R338W) in a patient with pituitary resistance to thyroid hormone (PRTH). The mutation existed in one of two hot spot areas in TRbeta gene where clusters of mutations have been found in subjects with generalized resistance to thyroid hormone (GRTH). Interestingly, R338W induces the phenotypical features responsible for PRTH. In the present study, we examined the functional properties of R338W in comparison with those of a GRTH-mutant, K443E. The levels of thyroid hormones and inappropriately elevated TSH (SITSH) were similar between subjects with K443E and R338W. Transcriptional activities and dominant negatives potencies were measured by CAT assay in CV1 cells transfected with each mutant TRbeta1 or along with wild-type TR. When a reporter gene containing T3-responsive elements (TRE), TRE-pal2, DR4 or myosin heavy chain alpha subunit, was used, transcriptional activation induced by R338W was higher than that by K443E. At 50 nM T3, K443E decreased the transcriptional activity of wild-type TRbeta1 on TRE-pal2 by 31.5%, while R338W reduced by 13.6% (n = 15, P < 0.05). Co-expression of retinoid X receptor (RXR) alpha increased transcriptional activity of R338W and K443E, but not of wild-type TRbeta1. Dominant negative activity on TRE-TSHalpha subunit of R338W was milder than that of K443E. When T3-binding activities of mutant TRbeta1s expressed in the cells were assayed under the same cell conditions for CAT assay, both mutant TRbeta1 showed remarkably reduced activity with no difference between the two. Gel mobility shift assay using TRE-DR4 showed poor homodimer formation of R338W. Heterodimerization with RXRalpha was similar between R338W, K443E and wild-type TRbeta1. The result of the present study suggested that R338W had relatively mild transcriptional and dominant negative activities on several TREs including TRE-TSHalpha subunit. We also showed poor homodimerization of R338W, which might be related to its weak dominant negative potency.

Young borderline hypertensives are hyperreactive to mental arithmetic stress: spectral analysis of R-R intervals

To investigate whether sympathetic tone and its reactivity to stress are increased in borderline hypertension, we compared pressor and autonomic nervous responses to mental arithmetic stress in male borderline hypertensives (BH) and normotensive volunteers (NT). Three age groups, 30, 40 and 50-year-old groups, which included 30 to 39, 40 to 49 and 50 to 59-year-old subjects, were studied. Fractional LF (%LF), fractional HF (%HF) and L/H, obtained from the power spectrum of R-R intervals, were used as indices of autonomic nervous function. Baseline autonomic nervous indices did not differ between NT and BH of any age group. Blood pressure rose higher during mental arithmetic stress in 50 than in 30-year-old NT but not in comparable age groups of BH. Pressor responses were augmented in BH compared to NT only in the 30-year-old group. However, the differences were not significant when pressor responses were expressed as percent increases in blood pressure. Both %L and L/H increased during arithmetic stress. The increase in %L did not differ between NT and BH but that in L/H (% delta L/H) was larger in 50 than in 30-year-old NT. % delta L/H was larger in BH than in NT only in the 30-year-old group. These findings suggest that both pressor and autonomic nervous responses to metal arithmetic stress were altered by aging and augmented in BH compared to NT in the 30-year-old group.

The sex ratio of mortality and its secular trends

BACKGROUND

The mortality level from all causes is different between populations and it has decreased for both men and women in most countries in the last decades. However, there is a difference in the male/female sex ratio of mortality between populations and its time trends and the reasons for these differences remain unclear.

METHODS

The sex ratio of all-cause mortality and the main causes of death, i.e. total cardiovascular disease and cancer, for 30 populations in 1988 (mean of 1987-1989), and the time trends of the sex ratio for 27 populations are analysed.

RESULTS

Large differences in the sex ratio of mortality exist among the studied populations. The sex ratio of all-cause, total cardiovascular and cancer mortality markedly increased in most countries during recent decades.

CONCLUSIONS

The sex ratio of all-cause mortality and its time trends correlated significantly and positively with the sex ratio of mortality and its time trends from total cardiovascular disease and cancer. The differences of the sex ratio of mortality and their time trends between populations cannot be explained by genetic factors. They could be attributed to differences in life style. A different exposure and different reaction to the risk factors of cardiovascular diseases and cancer, e.g. saturated fat intake, alcohol intake and smoking habits, between men and women are considered to be the main causes for these differences in the sex ratio of mortality.