Biomedical subjects

D Liao

Publications and source records attributed to D Liao.

At least 73 records · Page 4Linked to original sources

PubMed1998

SynGAP: a synaptic RasGAP that associates with the PSD-95/SAP90 protein family.

The PSD-95/SAP90 family of proteins has recently been implicated in the organization of synaptic structure. Here, we describe the isolation of a novel Ras-GTPase activating protein, SynGAP, that interacts with the PDZ domains of PSD-95 and SAP102 in vitro and in vivo. SynGAP is selectively expressed in brain and is highly enriched at excitatory synapses, where it is present in a large macromolecular complex with PSD-95 and the NMDA receptor. SynGAP stimulates the GTPase activity of Ras, suggesting that it negatively regulates Ras activity at excitatory synapses. Ras signaling at the postsynaptic membrane may be involved in the modulation of excitatory synaptic transmission by NMDA receptors and neurotrophins. These results indicate that SynGAP may play an important role in the modulation of synaptic plasticity.

Amino Acid Sequence↗

PubMed1998

Multiple metabolic syndrome is associated with lower heart rate variability. The Atherosclerosis Risk in Communities Study.

OBJECTIVE: To test at the population level whether people with multiple metabolic syndrome (MMS) disorders have reduced cardiac autonomic activity (CAA). RESEARCH DESIGN AND METHODS: We examined the association between the level of CAA and MMS disorders, at the degree of clustering and the segregate combination levels, using a random sample of 2,359 men and women aged 45-64 years from the biracial, population-based Atherosclerosis Risk in Communities (ARIC) Study. Supine resting 2-min beat-to-beat heart rate data were collected. High-frequency (HF) (0.15-0.35 Hz) and low-frequency (LF) (0.025-0.15 Hz) spectral powers, the ratio of LF to HF, and the SD of all normal R-R intervals (SDNN) were used as the conventional indices of heart rate variability (HRV) to measure CAA. The MMS disorders included hypertension, type 2 diabetes, and dyslipidemia. RESULTS: HRV indices were significantly lower in individuals with MMS disorders. The multivariable adjusted mean HF was 0.85 (beat/min)2 in subjects with all three MMS disorders, in contrast to 1.31 (beat/min)2 in subjects without any MMS disorder. At the segregated combination level, the multivariable adjusted means +/- SEM of HF were 1.34 +/- 0.05, 1.16 +/- 0.05, 1.01 +/- 0.17, and 1.34 +/- 0.05 (beat/min)2, respectively, for subjects without any MMS disorder, with hypertension only, with diabetes only, and with dyslipidemia only, and the means +/- SEM of HF were 0.93 +/- 0.04, 0.70 +/- 0.15, and 1.20 +/- 0.05 (beat/min)2, respectively, for subjects with diabetes and hypertension, diabetes and dyslipidemia, and hypertension and dyslipidemia. An increase in fasting insulin of 1 SD was associated with 88% higher odds of having a lower HF. The pattern of associations was similar for LF and SDNN. CONCLUSIONS: These findings suggest that MMS disorders adversely affect cardiac autonomic control and a reduced cardiac autonomic control may contribute to the increased risk of subsequent cardiovascular events in individuals who exhibit MMS disorders.

Arteriosclerosis↗

PubMed1998

[Finite element analysis of human tibia in vitro].

This investigation was aimed at the fatigue fracture of tibia that often occurs in soldiers, as well as in dancers and athletes. The data of ground reaction force(GRF) of soldiers were measured using a force platform in three common gaits: marching, parading and running. The stress distribution in tibia under these GRFs were analyzed with a FE model. The results showed that the smallest GRF(744.8N) is in quick marching, the next (1156.4N) in parading and the largest (1391.6N) in running. The stress distribution under GRF was mot uniform in the tibia. The maximum stresses occurred at a site 1/3 tibia length below the knee where tibia fracture is often seen clinically. The maximum stresses were 110 MPa and 115 MPa in parading and running respectively. This means that the tibial tractures in soldiers are mostly associated with stress, i.e. the greater the stress is, the higher the incidence of stress fracture comes about.

Adult↗

PubMed1997

Cytochrome P450 in the breast and brain: role in tissue-specific activation of xenobiotics.

It is still an open question as to whether, upon administration of procarcinogens to rodents, development of cancers in extrahepatic tissues is due to activation of these chemicals in the liver or to in situ activation within the tissue. The low level of P450 in many tissues means that it is very difficult to demonstrate the formation of significant amounts of reactive metabolites when these tissues are incubated with procarcinogens in vitro. It is our contention that the importance of tissue-specific activation of procarcinogens can best be decided when the cells which harbour P450 have been identified and the isozyme profile in the cells defined. With this aim in view, we have begun to characterize the forms of P450 in the breast and brain. Perhaps not surprisingly, the P450s in the breast are regulated as a function of age and hormonal status of rats and most of the breast P450 can be accounted for by hepatic forms. The P450 content of the brain, on the other hand, is very responsive to environmental factors. The quantity of P450 as well as the isozyme profile is altered by drugs and chemicals in the environment. The P450s induced in the brain are similar to liver P450s, but the constitutive forms are not. P450s of the 1A family are inducible in both tissues and this indicates that heterocyclic amines can be activated in the brain and polycyclic aromatic hydrocarbons in the breast. The cells in which this activation can occur remain to be identified.

Animals↗

PubMed1997

Cardiac autonomic function and incident coronary heart disease: a population-based case-cohort study. The ARIC Study. Atherosclerosis Risk in Communities Study.

Cardiac autonomic activity, as assessed by heart rate variability, has been found to be associated with postmyocardial infarction mortality, sudden death, and all-cause mortality. However, the association of heart rate variability and the incidence of coronary heart disease (CHD) is not well described. The authors report on the association of baseline cardiac autonomic activity (1987-1989) with incident CHD after 3 years (1990-1992) of follow-up of the Atherosclerosis Risk in Communities Study cohort selected from four study centers in the United States by using a case-cohort design. The authors examined 137 incident cases of CHD and a stratified random sample of 2,252 examinees free of CHD at baseline. Baseline, supine, resting beat-to-beat heart rate data were collected. High- (0.16-0.35 Hz) and low- (0.025-0.15 Hz) frequency spectral powers and high-/low-frequency power ratio, estimated from spectral analysis, and standard deviation of all normal R-R intervals, calculated from time domain analysis, were used as the conventional indices of cardiac parasympathetic, sympatho-parasympathetic, and their balance, respectively. Incident CHD was defined as hospitalized myocardial infarction, fatal CHD, or cardiac revascularization procedures during 3 years of follow-up. The age, race, gender, and other CHD risk factor-adjusted relative risks (and 95% confidence intervals) of incident CHD comparing the lowest quartile with the upper three quartiles of high-frequency power, low-frequency power, high-/low-frequency power ratio, and standard deviation of R-R intervals were 1.72 (95% confidence interval (CI) 1.17-2.51), 1.09 (95% CI 0.72-1.64), 1.25 (95% CI 0.84-1.86), and 1.39 (95% CI 0.94-2.04), respectively. The findings from this population-based, prospective study suggest that altered cardiac autonomic activity, especially lower parasympathetic activity, is associated with the risk of developing CHD.

Case-Control Studies↗

PubMed1997

Nucleation and polymerization of sickle hemoglobin with Leu beta 88 substituted by Ala.

We have measured the solubility, and the rates of homogeneous and heterogeneous nucleation on sickle hemoglobin (HbS beta 6 Glu-->Val) additionally modified by site-directed mutagenesis to possess Ala rather than Leu at beta 88, which forms part of the receptor site for beta 6 Val in the sickle polymer. The solubility of the hemoglobin is increased at all temperatures, and is about 29 g/dl at 25 degrees C. Polymerization kinetics, induced by laser photolysis and observed by light-scattering intensity, showed exponential growth with rates about 300 times slower than experiments done on similar concentrations of HbS. When polymerization is carried out in small volumes, the time of measurable light-scattering signal to reach one-tenth of its final value (denoted as the tenth time) showed stochastic fluctuations, as is seen in pure HbS. Homogeneous nucleation rates were measured by observing distributions of tenth times and these rates were slowed by the mutation by almost 1000-fold relative to pure HbS. The kinetics, including the exponential progress curves and shape of the tenth time distributions, are well described by the double nucleation mechanism for polymerization. Analysis of the homogeneous nucleation rates leads to the surprising conclusion that the mutation has scarcely changed the energy of the intermolecular contacts despite the increase in solubility of the double mutant. This conclusion is supported by the stereochemistry of the modified contact site, in which the amount of exposed hydrophobic surface appears to be unchanged by the mutation. The increased solubility must therefore result from decreased motional freedom of molecules within the polymer, which could arise from tighter packing into the enlarged receptor pocket. This points up the ability of kinetic analysis to reveal important thermodynamic properties of assembly, and underlines the importance of the vibrational degrees of freedom in setting the final equilibrium constant. Chemical modifications to restrict vibrations and enhance the cost of polymerization may prove useful in constructing compounds to act as inhibitors of sickle cell gelation.

Binding Sites↗

PubMed1997

Concerted evolution of the tandemly repeated genes encoding human U2 snRNA (the RNU2 locus) involves rapid intrachromosomal homogenization and rare interchromosomal gene conversion.

We have surveyed the tandemly repeated genes encoding U2 snRNA in a diverse panel of humans. We found only two polymorphisms within the U2 repeat unit: a SacI polymorphism (alleles SacI+ or SacI-) and a CT microsatellite polymorphism (alleles CT+ or CT-). Surprisingly, individual U2 tandem arrays are entirely SacI+ or SacI-, and entirely CT+ or CT-, although the SacI and CT alleles can occur in any combination. We also found that polymorphisms in the left and right junction regions flanking the tandem array fall into only two haplotypes (JL+ and JL-, JR+ and JR-). Most surprisingly, JL+ is always associated with JR+, and JL- with JR-. Thus individual U2 arrays do not exchange flanking markers, despite independent assortment and subsequent homogenization of the SacI and CT alleles within the U2 repeat units. We propose that the primary driving force for concerted evolution of the tandem U2 genes is intrachromosomal homogenization; interchromosomal genetic exchanges are much rarer, and reciprocal nonsister chromatid exchange apparently does not occur. Thus concerted evolution of the U2 tandem array occurs in situ along a chromosome lineage, and linkage disequilibrium between sequences flanking the U2 array may persist for long periods of time.

Animals↗

PubMed1997

The prevalence and severity of white matter lesions, their relationship with age, ethnicity, gender, and cardiovascular disease risk factors: the ARIC Study.

White matter lesions (WMLs) detected by cerebral magnetic resonance imaging (MRI) are putatively a consequence of cerebral hypoperfusion or ischemia. We investigated the prevalence, severity and correlates of WMLs in a population-based sample of 1,920 African-American and European-American men and women aged 55-72 years, during the second follow-up examination of the Atherosclerosis Risk in Communities Study. The spin density images from 1.5-tesla MRI scans were used to define WMLs using a 0-9 scale with 0 for normal and 9 for most severe WMLs. Age was positively associated with the prevalence (percent) and severity of WMLs. African-Americans had lower overall prevalence of WMLs, but a higher prevalence of relatively more severe WMLs, than European-Americans. After adjusting for age, sex, and ethnicity, WMLs were significantly associated with smoking, lower education, hypertension, systolic blood pressure, and pulse pressure, and weakly associated with diastolic blood pressure. The associations of smoking, alcohol intake, systolic and diastolic blood pressure, pulse, pressure, and hypertension were stronger in African-Americans than in European-Americans (p < 0.15 for interactions by ethnicity). This population-based MRI study documents significant relationships between several cardiovascular disease risk factors and WMLs. The findings suggest that such factors play a role in the pathogenesis of WMLs, an elements linked to hypoperfusion and/or fluid accumulation, which presumably lead to WMLs. African-Americans exhibited both a higher proportion of normal white matter and a higher proportion of relatively more severe WMLs than European-Americans.

Age Factors↗

PubMed1997

Familial history of stroke and stroke risk. The Family Heart Study.

BACKGROUND AND PURPOSE: Although familial history of stroke is generally perceived to be an important marker of stroke risk, very few epidemiological studies have been published to address this hypothesis. We sought to examine whether familial history of stroke is associated with the prevalence of stroke in the Family Heart Study, a National Heart, Lung, and Blood Institute-supported multicenter study of the familial, genetic, and nongenetic determinants of cardiovascular disease in populations. METHODS: The personal and familial histories of stroke were assessed in 3168 individuals (probands) who were at least 45 years old and 29,325 of their first-degree relatives with the use of a standardized questionnaire. RESULTS: The age-, ethnicity-, and sex-adjusted stroke prevalences were 4.8%, 4.9%, and 3.9% in probands with a positive familial, paternal, and maternal history of stroke, respectively, in comparison with 2.0% in probands without any positive familial history (P < .01). The age-, ethnicity-, and sex-adjusted odds ratios (95% confidence interval) of stroke were 2.00 (1.13, 3.54) for a positive paternal and 1.41 (0.80, 2.50) for a positive maternal history of stroke. Additional statistical adjustment for the proband's history of elevated cholesterol level, cigarette smoking status, history of coronary heart disease, hypertension, and diabetes did not alter the associations. A similar pattern was seen for African Americans and European Americans. CONCLUSIONS: The increased risk of stroke among persons with a positive familial history of stroke compared with those without a familial history of stroke is consistent with the expression of genetic susceptibility, a shared environment, or both in the etiology of stroke.

Black or African American↗

PubMed1997

[Acupoints specificity in promoting the plasticity of cat spinal lamina II with acupuncture-quantitative EM study].

Our previous studies have shown acupoints stimulation might promote the plasticity of spinal cord. In order to explore the acupoints specificity of the effects we used ten cats with unilateral dorsal partial rhizotomy (L1-S2, except L6). The rhizotomy sides of five cats received acupuncture stimulation (acupoints stimulation group) at Zusanli (St36), Xuanzhong (GB 39), Futu (St32) and Sanyinjiao (Sp 6) in the innervated areas of L6 spinal nerve for two courses, 10 days per coure. The rest cats were subjected to needling at the areas adjacent to the acupoints (nonacupoints stimulation group). Quantitative EM method was applied to detect (the population of synaptic terminals in lamina II 30 days postoperation. According to the number of synaptic contacts between synaptic terminal and postsynaptic element, synaptic terminals were divided into two types: the simple terminal (ST) coming from spinal and descending tract, and the complex terminal (CT) from dorsal root. The average numbers of the two types' synaptic terminals per photo were compared directly because the acupoints and nonacupoints groups' transverse areas of lamina II showed no significant difference. The results showed: (1) There was no significant difference for ST number between two groups. Associated with our previous study that acupoints stimulation did not influence ST number, the present result indicated that nonacupoints stimulation had no effect on ST number, (2) The complex terminal numbers were statistically different (P < 0.05). The percentage of CT in the nonacupoints group was only 53% of that in the acupoints group. This result was similar to two other nonacupuncture groups in our laboratory (the percentages were 59% and 62% respectively). It indicates that the effect of nonacupoints stimulation is similar to that of nonneeding, i.e. nonacupoints stimulation does not promote the plasticity of spinal lamina II or there might be acupoints specificity in promoting the plasticity of spinal laminal II.

Acupuncture Points↗

PubMed1996

Database of mutations in the p53 and APC tumor suppressor genes designed to facilitate molecular epidemiological analyses.

Germline and somatic mutations in the p53 and APC genes contribute to neoplasia. The patterns of these and other acquired mutations in cancers reflect environmental mutagens and endogenous factors that contribute to carcinogenesis. Herein, we describe a database of almost 2,300 mutations in the p53 and APC genes published until September 1, 1993. In addition to cataloging the mutations, multiple fields of information have been added to facilitate future molecular epidemiological analyses of human cancer. The accuracy of the database has been checked by the present authors and, by soliciting feedback from the original corresponding authors. The strengths and limitations of the primary literature are discussed.

Computer Communication Networks↗

PubMed1996

A computer algorithm to impute interrupted heart rate data for the spectral analysis of heart rate variability--the ARIC study.

The shorter term beat-to-beat heart rate data collected from the general population are often interrupted by artifacts, and an arbitrary exclusion of such individuals from analysis may significantly reduce the sample size and/or introduce selection bias. A computer algorithm was developed to label as artifacts any data points outside the upper and lower limits generated by a 5-beat moving average +/- 25% (or set manually by an operator using a mouse) and to impute beat-to-beat heart rate throughout an artifact period to preserve the timing relationships of the adjacent, uncorrupted heart rate data. The algorithm applies Fast Fourier Transformation to the smoothed data to estimate low-frequency (LF; 0.025-0.15 Hz) and high-frequency (HF; 0.16-0.35 Hz) spectral powers and the HF/LF ratio as conventional indices of sympathetic, vagal, and vagal-sympathetic balance components, respectively. We applied this algorithm to resting, supine, 2-min beat-to-beat heart rate data collected in the population-based Atherosclerosis Risk in Communities study to assess the performance (success rate) of the algorithm (N = 526) and the inter-and intra-data-operator repeatability of using this computer algorithm (N = 108). Eighty-eight percent (88%) of the records could be smoothed by the computer-generated limits, an additional 4.8% by manually set limits, and 7.4% of the data could not be processed due to a large number of artifacts in the beginning or the end of the records. For the repeatability study, 108 records were selected at random, and two trained data operators applied this algorithm to the same records twice within a 6-month interval of each process (blinded to each other's results and their own prior results). The inter-data-operator reliability coefficients were 0.86, 0.92, and 0.90 for the HF, LF, and HF/LF components, respectively. The average intra-data-operator reliability coefficients were 0.99, 0.99, and 0.98 for the HF, LF, and HF/LF components, respectively. These results indicate that this computer algorithm is efficient and highly repeatable in processing short-term beat-to-beat heart rate data collected from the general population, given that the data operators are trained according to standardized protocol.

Algorithms↗

PubMed1996

Solubility of sickle hemoglobin measured by a kinetic micromethod.

We have developed a photolytic method to determine the concentration of reactive hemes in a solution in the presence of a trace amount of CO. By measurement of the bimolecular rate of CO binding, and by calibration of the rate constant under equivalent conditions, the concentration of the reactive hemes can be determined. In a solution of sickle hemoglobin, the molecules in the gel contribute negligibly to the recombination rate, allowing the concentration of the molecules in the solution phase to be determined. To optimize signal to noise, modulated excitation methods were employed, although the method could also be used with pulse techniques and suitable signal averaging. Because the optical method employs a microspectrophotometer, only a few microliters of concentrated Hb solution is required to reproduce the entire temperature dependence of the solubility previously determined by centrifugation using milliliter quantities of solutions of the same concentration. This should be especially useful for studies of site-directed mutants, and we present results obtained on one such HbS in which Leu 88 beta has been replaced by Ala. The free energy difference in the polymerization of the Leu 88 beta double mutant is consistent with known differences in the amino acid hydrophobicities. The calibration required for these experiments also provides an excellent determination of the activation energy for binding the first CO to deoxy Hb.

Alanine↗

PubMed1996

Population-based study of heart rate variability and prevalent myocardial infarction. The Atherosclerosis Risk in Communities Study.

Clinically based studies have indicated that patients who have suffered myocardial infarction (MI) exhibit lower heart rate variability (HRV). Such associations have not been reported at the population level. To investigate whether MI is related to lower HRV in the general population, the authors examined a stratified random sample of 2,243 men and women aged 45-64 years, of whom 260 had had MI and 1,983 were free of any coronary heart disease manifestations. All were part of the biracial cohort of the Atherosclerosis Risk in Communities study sampled from four United States communities. Resting, 2-minute supine heart rate data were analyzed using spectral analysis to estimate high-frequency (0.16-0.35 Hz) and low-frequency (0.025-0.15 Hz) spectral powers as conventional indices of HRV. The mean levels of high-frequency powers were 1.02 and 1.23 (beats/min)2 for MI and non-MI groups, respectively (P < .05), and the low-frequency means were 2.46 and 3.11 (beats/min)2 for MI and non-MI groups, respectively (P < .01). Age, race, and sex-adjusted odds ratios (95% confidence interval) of lower high-frequency and low-frequency powers contrasting MI to non-MI individuals were 1.52 (range, 1.09-2.10) and 1.54 (range, 1.12-2.10), respectively. After adjustment for use of beta-blocker medication, the odds ratios (95% confidence interval) were 1.26 (range, 0.88-1.81) and 1.22 (range, 0.87-1.69) for lower high-frequency and low-frequency powers, respectively. The findings from this first population-based study of prevalent MI and HRV provide support for an inverse association between MI and lower HRV. However, adjusting for beta-blocker use eliminates the statistical association. These findings confirm that impaired HRV is found in individuals with prevalent MI, even when drawn as a sample of community-dwelling individuals. This impaired HRV may contribute to the increased risk of subsequent cardiovascular events previously observed in survivors of acute MI. The cross-sectional data also suggest that use of beta-blockers diminishes the odds of lower HRV associated with MI.

Adrenergic beta-Antagonists↗

PubMed1996

Association of cardiac autonomic function and the development of hypertension: the ARIC study.

To relate cardiac autonomic function measured by heart rate variability (HRV) with prevalent and incident hypertension at the population level, the authors examined a stratified random sample of 2,061 examinees from the biracial Atherosclerosis Risk in Communities (ARIC) cohort. Baseline, supine, resting beat-to-beat heart rate data were collected. High frequency (HF, 0.15 to 0.35 Hz), low frequency (LF, 0.025 to 0.15 Hz) spectral powers, and LF/HF ratio, estimated from spectral analysis, and standard deviation of all normal RR intervals (SDNN), calculated from time domain analysis, were used as the conventional indices of cardiac autonomic function. From this sample, 650 prevalent hypertensives were identified. Of those normotensive at baseline (n = 1,338), 64 participants developed hypertension during 3 years of follow-up. In the cross-sectional analysis, the adjusted geometric means of HF were 1.26, 1.20, and 1.00 (beat/min)2 for normotensives, untreated hypertensives, and treated hypertensives, respectively; means of LF were 3.24, 3.26, and 2.58; means of LF/HF ratio were 2.57, 2.70, and 2.56; and means of SDNN were 39, 34, and 35 (ms) respectively. In the prospective analysis, a statistically significant, graded inverse association between baseline HF and the risk of incident hypertension was observed: the adjusted incident odds ratios (95% CI) were 1.00, 1.46 (0.61, 3.46), 1.50 (0.65, 3.50) and 2.44 (1.15, 5.20) from the highest to the lowest quartile of HF. No clear pattern of association was observed for LF. Significant trends of association for LF/HF and SDNN and incident hypertension were also found. These results suggest that cardiac autonomic function is associated with prevalent hypertension, and that reduced vagal function and the imbalance of sympatho-vagal function are associated with the risk of developing hypertension.

Adult↗

PubMed1996

A NusG-like protein from Thermotoga maritima binds to DNA and RNA.

The NusG-like protein from Thermotoga maritima was expressed in Escherichia coli and purified to homogeneity. Purified T. maritima NusG exhibited a generalized, non-sequence-specific and highly cooperative DNA and RNA binding activity. The complexes formed between nucleic acid and T. maritima NusG were unable to penetrate a polyacrylamide or agarose gel. The affinity of the protein for DNA was highest in buffers containing about 50 mM salt. The DNA-protein complexes could not be stained with ethidium bromide, were resistant to digestion by TaqI endonuclease, were able to be transcribed in vitro by T. maritima RNA polymerase, and contained a minimum of about 30 to 40 monomers of NusG per kb of duplex DNA. The protein had comparable affinities for duplex DNA and RNA but a lower affinity for single-stranded DNA. Electron microscopy showed that the DNA in the complex is condensed within a large structure that resembles the complex between DNA and histone-like protein Hcl from Chlamydia trachomatis. Neither the wild-type T. maritima nusG gene nor a deletion derivative more similar to the E. coli gene was able to substitute for the essential E. coli nusG. Two variants of the NusG protein were constructed, expressed, and purified: one contains only the entire 171-amino-acid insertion that is unique to T. maritima NusG, and the other has only the sequences present in NusG homologs from E. coli and other eubacteria. Both variants exhibited similar DNA and RNA binding behavior, although their apparent affinities were 5- to 10-fold lower than that of the wild-type T. maritima NusG.

Amino Acid Sequence↗

PubMed1996

Presence and severity of cerebral white matter lesions and hypertension, its treatment, and its control. The ARIC Study. Atherosclerosis Risk in Communities Study.

BACKGROUND AND PURPOSE: White matter lesions (WML) may result from cerebral hypoperfusion or ischemia. We investigated the association of WML with blood pressure, hypertension, and its treatment and control. METHODS: A random sample of 1920 participants aged 55 to 72 years in the Atherosclerosis Risk in Communities Study (ARIC) was examined. Spin-density 1.5-T MRI scan images were coded from 0 for normal to 9 for most severe WML. Hypertension was defined as systolic or diastolic pressure > or = 140/90 mm Hg or use of antihypertensive medication. RESULTS: The percentages of persons with WML grades 0 through 2 and 3 through 9, respectively, were as follow: normotensive, 92.4% and 7.6%, versus all hypertensive subjects, 83% and 17% (P < .001); and treated controlled hypertensive, 86% and 14%, versus treated uncontrolled hypertensive subjects, 76% and 24% (P = .003). Multivariable adjusted odds ratios (95% confidence intervals) for WML grade > or = 3 relative to normotensive subjects was 2.34 (1.71 to 3.20) for all hypertensives, 1.99 (1.19 to 3.08) for untreated hypertensives, 1.94 (1.32 to 2.85) for treated controlled hypertensives, and 3.40 (2.30 to 5.03) for treated uncontrolled hypertensives. After additional adjustment for hypertension duration, treatment, and control status, the odds ratios (95% confidence intervals) for a 1 SD increase of systolic and diastolic blood pressure were 1.43 (1.11 to 1.85) and 1.16 (0.94 to 1.43), respectively. CONCLUSIONS: Hypertension is associated with increased odds of WML, and treated uncontrolled hypertensive subjects have greater odds of WML than those with treated controlled hypertension. The data suggest that the level of blood pressure, especially systolic blood pressure, is related to WML, additional to the effects of categorically defined hypertension and its treatment and control status.

Aged↗

PubMed1996

[A morphometric study on hippocampus of epileptic rats induced by coriaria lactone].

This experiment was carried out with these rats were injected with 3.8 microliters (19 micrograms) convulsive dosage of coriaria lactone (CL) in the left cerebral motor cortex of the forelimb to induce acute focal epilepsy, while the other 5 rats as controls (no seizure) received normal saline solution of the same volume and at the same location. The brains were taken after seizuring for 60 min. The volume (water displacement method) and weight of the brain were measured. The brain was cut coronally and the structures of hippocampus were compared morphologically with those of the pair-matched control. The area of hippocampal formation was measured with paraffin section by test grid under 40x. The mean size (Feret's diameter) of pyramidal neurons in CA1 region was measured with semithin section by ocular micrometer under 1000x. The areal fraction of several organelles of the CA1 pyramidal cells was measured with EM negative film by magnifier. Under conditions of the consistent reference space, especially the size of CA1 pyramidal cells, the areal fraction of rough endoplasmic reticulum, lysosome and mitochondria increased significantly (P < 0.05) in epileptic rats. It indicated that their volume increased. The results show that certain ultrastructural changes have taken place after seizuring for 60 min.

Animals↗