Changes in phagocytosis and expression of microglial cells in craniocerebral injury mice models.

The objective of this study was to investigate the changes in phagocytic function and expression quantities of CD11b and tumor necrosis factor-α (TNF-α) among microglia cells of craniocerebral injury mice. Modified Feeney method was used to establish the craniocerebral injury mice models. Twenty-one male SPF mice were divided into a control group and a trauma group. The scalp was incised and a bone window was opened in the control group without cerebral injury. In the trauma group, the mice were sacrificed after the craniocerebral injury at 1, 3, 6, 12, 24 and 48 h to make frozen sections of cerebral tissues. The phagocytic rate of microglia cells was observed by using fluorescent microsphere. The changes in the expression quantities of CD11b and TNF-α were detected by enzyme-linked immuno sorbent assay (ELISA). The phagocytic ability of the microglia cells after the craniocerebral injury increased at 1 h after injury compared with that of the control group (P less than 0.01). The expression of surface antigen CD11b of the microglia cells and the expression of TNF-α increased at 1, 3, 6, 12, 24 and 48 h after the injury compared with those of the control group (P less than 0.01). The phagocytic ability of the microglia cells increased. The expressions of CD11b and TNF-α were also gradually enhanced in the acute phase after craniocerebral injury, and then gradually decreased to the normal level. The expressions of CD11b and TNF-α indicated a high consistency with the changing trend of the phagocytic ability, suggesting that the microglia cells may participate in the regulation of the inflammatory process of the central nervous system through absorbing apoptotic cells and increasing and secreting inflammatory and anti-inflammatory factors.

Construction of an anthropopathic abdominal phantom for accuracy validation of deformable image registration.

The purpose of this study is to design and fabricate an anthropopathic abdominal phantom for accuracy evaluation of deformable image registration (DIR) algorithms in adaptive radiation therapy. The constructed deformable organs, including the liver, kidney, spleen and stomach, are made of mixture of polyvinyl chloride (PVC) and softener dioctyl terephthalate, while the rigid structures, i.e. vertebrae, are made of white cement. Relation between the PVC-softener blending ratio and organ CT number is studied, and three-dimensional printing technic is employed to create highly anthropopathic organs in terms of organ shape and density. Detailed steps for phantom construction, landmark point placement and choice of phantom ingredients and construction recipe are introduced. Preliminary results of the mechanical properties of the fabricated organs are also presented. The experimental results indicate that the constructed phantom has satisfactory elastic characteristics and close CT number with corporal organs, and can potentially be applied to simulate real abdominal organ deformation in geometric accuracy validation of DIR algorithms.

Comparison of 16S rRNA gene PCR and blood culture for diagnosis of neonatal sepsis.

UNLABELLED: Septicemia is a common cause of morbidity and mortality among newborns in the developing world. However, accurate clinical diagnosis of neonatal sepsis is often difficult because symptoms and signs are often nonspecific. Blood culture has been the gold standard for confirmation of the diagnosis. However, the sensitivity is low and results are usually not promptly obtained. Therefore, the diagnosis of sepsis is often based on clinical signs in association with laboratory tests such as platelets count, immature/total neutrophils ratio (I/T), and a rise in C-reactive protein (CRP). Polymerase chain reaction (PCR) methods for the detection of neonatal sepsis represent new diagnostic tools for the early identification of pathogens. METHODS: During a 4-month prospective study, 16S rRNA PCR was compared with conventional blood culture for the diagnosis of neonatal bacterial sepsis. In addition, the relationship between known risk factors, clinical signs, laboratory parameters, and the diagnosis of sepsis was considered. RESULTS: Sepsis was suspected in 706 infants from the intensive neonatal care unit. They all were included in the study. The number of positive cultures and positive PCR results were 95 (13.5%) and 123 (17.4%), respectively. Compared with blood culture, the diagnosis of bacterial sepsis by PCR revealed a 100.0% sensitivity, 95.4% specificity, 77.2% positive predictive value, and 100.0% negative predictive value. In this study, Apgar scores at 5 min, weight, icterus, irritability, feeding difficulties, gestational age (GA), premature rupture of membrane (PRM), platelets count, I/T, and a marked rise in CRP were important in establishing the diagnosis of sepsis in the newborn. In addition, weight, GA, PRM, irritability, duration of antibiotic usage, mortality rate, and number of purulent meningitis cases were significantly different between early-onset sepsis and late-onset sepsis. CONCLUSION: 16S rRNA PCR increased the sensitivity in detecting bacterial DNA in newborns with signs of sepsis, allowed a rapid detection of the pathogens, and led to shorter antibiotic courses. However, uncertainty about the bacterial cause of sepsis was not reduced by this method. 16S rRNA PCR needs to be further developed and improved. Blood culture is currently irreplaceable, since pure isolates are essential for antimicrobial drug susceptibility testing.

High frequency variations of Helicobacter pylori isolates in individual hosts in a Chinese population.

BACKGROUND: Colonization of individual hosts by multiple Helicobacter pylori genotypes may be one reason why this infection is persistent and difficult to eradicate. METHODS: In order to study the diversity of H. pylori in individuals, a modified randomly amplified polymorphic DNA (RAPD) method was applied using primary culture isolates instead of passaged cultures. RESULTS: The results showed that variations in H. pylori were prevalent among individuals in the Chinese population, and the incidence of multiple colonization was 99.1% (115/116), significantly higher than in other reports. Moreover, the number of RAPD genotypes was found to be significantly associated with the process of disease development (p<0.05). Indeed, a trend for a higher number of RAPD genotypes within a single host (up to five genotypes) was observed as the disease developed or became more serious. After subculturing for three generations in our experiment, some genotypes present in the primary cultures were lost. The different genotypes in one patient may have originated from a single ancestral strain, as determined by analysis of six H. pylori housekeeping gene alleles, most of which were shown to be identical. CONCLUSIONS: These results suggest that investigating isolates of the primary culture will better reflect the H. pylori diversity in individuals. Also, they indicate that continuous variation of one strain in the gastric microenvironment may be the main cause of H. pylori diversity in individuals in the Chinese population.

Core genome haplotype diversity and vacA allelic heterogeneity of Chinese Helicobacter pylori strains.

The human gastric pathogen, Helicobacter pylori, has co-evolved with its host and established itself in the human stomach possibly millions of years ago. Therefore, the diversity of this bacterium is important in its clinical manifestations. Our aim has been to evaluate the genetic diversity of 40 H. pylori clinical isolates from four different parts of China. The methods of multi-locus sequence typing and vacA allele genotyping were used to assess their genetic diversity. To discriminate MLST, the vacA genotype method was used to identify strains. Patients from the northern, eastern, southern, and southwestern parts of China were recruited randomly from the cities of Beijing, Shanghai, Guangzhou, and Chongqing, respectively. Most of the sequence types are new and have never been reported in the database of the H. pylori multi-locus sequence typing system. The most prevalent vacA genotype in patients was s1a/m2 (80.0%), followed by s1b/m2 (17.5%). In contrast, the s1a/m1 genotype was scarcely represented (2.5%). The vacA genotype varied for each ST. These results showed that the MLST method offers high resolution of the H. pylori isolates in China when compared to vacA genotyping. The vacA allelic s1a has been correlated with the peptic ulcer. Because of the paucity of data on human isolates due to the absence of systematic investigations of H. pylori in China, the data provide useful information for understanding the epidemiology of H. pylori in China from the viewpoint of nucleotide sequence databases.

Identification of SOX4 target genes using phylogenetic footprinting-based prediction from expression microarrays suggests that overexpression of SOX4 potentiates metastasis in hepatocellular carcinoma.

A comprehensive microarray analysis of hepatocellular carcinoma (HCC) revealed distinct synexpression patterns during intrahepatic metastasis. Recent evidence has demonstrated that synexpression group member genes are likely to be regulated by master control gene(s). Here we investigate the functions and gene regulation of the transcription factor SOX4 in intrahepatic metastatic HCC. SOX4 is important in tumor metastasis as RNAi knockdown reduces tumor cell migration, invasion, in vivo tumorigenesis and metastasis. A multifaceted approach integrating gene profiling, binding site computation and empirical verification by chromatin immunoprecipitation and gene ablation refined the consensus SOX4 binding motif and identified 32 binding loci in 31 genes with high confidence. RNAi knockdown of two SOX4 target genes, neuropilin 1 and semaphorin 3C, drastically reduced cell migration activity in HCC cell lines suggesting that SOX4 exerts some of its action via regulation of these two downstream targets. The discovery of 31 previously unidentified targets expands our knowledge of how SOX4 modulates HCC progression and implies a range of novel SOX4 functions. This integrated approach sets a paradigm whereby a subset of member genes from a synexpression group can be regulated by one master control gene and this is exemplified by SOX4 and advanced HCC.

Investigation of rice transgene flow in compass sectors by using male sterile line as a pollen detector.

Rice is the most important staple food in the world. The rapid development of transgenic rice and its future commercialization have raised concerns regarding transgene flow and its potential environmental risk. It is known that rice is a self-pollinated crop; the outcrossing rate between common cultivars is generally less than 1%. In order to improve the detection sensitivity of rice transgene flow, a male sterile (ms) line BoA with a high outcrossing rate was used as a pollen detector in this study. A concentric circle design was adopted, in which the transgenic rice B2 containing bar gene as a pollen donor was planted in the center circle and the recipient BoA was planted in eight compass sectors. The frequency of transgene flow in compass sectors was analyzed by continuous sampling to generate cumulative data. The results of two years with sound reproducibility demonstrated that the rice gene flow was closely associated with the wind direction. According to the mean frequency of transgene flow, the eight sectors can be divided into two groups: a higher frequency group downstream of the prevailing wind (DPW) with a mean frequency ranging from 6.47 to 26.24%, and a lower frequency group lateral to or upstream of the prevailing wind (UPW) with a mean frequency of 0.39 to 3.03%. On the basis of the cumulative data, 90-96% of the cumulative gene flow events occurred in the four DPW sectors, while it was 4-10% in the four UPW sectors. By using these systematic data, simulation models and isograms of transgene flow in the eight compass sectors were calculated and drawn, respectively.

Immunohistochemical and molecular assessment of human herpesvirus type 8 in gastrointestinal tumours.

BACKGROUND: Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract, histologically identified as highly cellular spindle or epithelioid cell tumours, and often positive for CD34 (60-70%). Kaposi's sarcomas (KSs) are similar to GISTs: they are most often found in the gastrointestinal tract (although cutaneous lesions do occur), they are also composed of spindle or epithelioid cells (although erythrocytes are also seen), and the tumour cells are nearly all positive for CD34. Human herpesvirus type 8 (HHV-8) DNA has been found consistently in all types of KS, in particular in CD34 positive KS tumour cells. However, the association between HHV-8 and GIST has not been investigated. AIMS: To assess the presence of HHV-8 in GISTs. METHODS: Paraffin wax embedded tissues of 86 primary GISTs and their recurrent or metastatic tumours were analysed immunohistochemically for the CD34 antigen and HHV-8 latent nuclear antigen 1 (LNA-1) and by means of the nested polymerase chain reaction (PCR) and real time PCR for HHV-8 DNA. RESULTS: None of the 86 GISTs contained HHV-8 DNA sequences or LNA-1 positive cells. CONCLUSIONS: These results demonstrate the lack of HHV-8 infection in GIST tumour cells. HHV-8 does not appear to play a role in the pathogenesis of GIST, irrespective of the status of the tumour.

Water quality management in the Kaoping River watershed, Taiwan.

The Kaoping River basin is the largest and the most intensively used river basin in Taiwan. It is 171 km long and drains a catchment of more than 3,250 km2. Based on the current water quality analysis, the Kaoping River is heavily polluted. Concern about the deteriorating condition of the river led the Government of Taiwan to amend the relevant legislation and strengthen the enforcement of the discharge regulations to effectively manage the river and control the pollution. Investigation results demonstrate that both point and non-point source pollutants are now the causes of biochemical oxygen demand (BOD), nutrients, and pathogens in the river. The main water pollution sources are livestock wastewater from hog farms, municipal wastewater, industrial wastewater, non-point source (NPS) pollutants from agricultural areas, and leachate from riverbank landfills. The current daily BOD, NH3-N, and TP loadings to Kaoping River are 74,700, 39,400, and 5,100 kg, respectively. However, the calculated BOD, NH3-N, and TP carrying capacities are 27,700, 4,200, and 600 kg per day. To protect public health and improve the river water quality, a comprehensive management and construction strategy is proposed. The proposed strategy includes the following measures to meet the calculated river carrying capacity: (1) a hog ban in the entire Kaoping River basin, (2) sewer system construction to achieve 30% of connection in the basin within 10 years, (3) removal of 10 riverbank landfills, and (4) enforcement of the industrial wastewater discharge standards. After the implementation of the proposed measures, the water quality should be significantly improved and the BOD and nutrient loadings can be reduced to below the calculated carrying capacities.

[Imaging diagnosis and forensic appraisal of orbital fracture].

Misdiagnosis and missed diagnosis are common in forensic appraisal of orbital fracture. Now imaging technology is very important for studying the forensic features of orbital fracture and evaluating the degree of injury. This article reviews the classification, pathogenesis and imaging diagnosis of orbital fracture. It may do some help to forensic appraisal of orbital fracture.

A missense mutation of the nitric oxide synthase (eNOS) gene (Glu298Asp) in five patients with coronary artery disease--case reports.

The authors report five patients with a missense mutation of the endothelial nitric oxide synthase (eNOS) gene (Glu298Asp) who have angiographically proven coronary artery disease (CAD). They compare their clinical findings and coronary arteriographic characteristics. They conclude that these case reports show that this mutation is not solely responsible for development of CAD. Diabetes mellitus, smoking, and hyperlipidemia are other risk factors.

Combined effects of probucol and benzafibrate on lipoprotein metabolism and liver cholesteryl ester transfer protein mRNA in cholesterol-fed rabbits.

Probucol decreases and bezafibrate increases plasma high density lipoprotein-cholesterol (HDL-C) levels in humans. This study was performed to determine whether the HDL-C-lowering effects of probucol could be reversed by treatment with bezafibrate in hypercholesterolemic rabbits. Forty-nine normolipidemic Japanese White rabbits were divided into 5 groups [group 1: normal chow; group 2: 0.2% cholesterol (Ch) diet; group 3: 0.2% Ch and 1% probucol diet; group 4: 0.2% Ch and 1% bezafibrate diet; group 5: 0.2% Ch and 1% probucol plus 1% bezafibrate diet] and treated for 8 weeks. Plasma lipids, cholesteryl ester transfer protein (CETP) activity in the lipoprotein-deficient plasma fraction, CETP mRNA in liver tissue and plasma drug concentrations were investigated. Serum total cholesterol (TC) increased after the rabbits in groups 2, 3, 4 and 5 were fed Ch, but overall, no significant differences were observed in serum TC and triglyceride (TG) among these groups. Serum HDL-C levels increased (p<0.01) in the bezafibrate-treated group, but a significant (p<0.05) reduction in HDL-C was observed in both the Ch + probucol (group 3) and Ch + probucol plus bezafibrate (group 5) groups; no significant difference was observed between groups 3 and 5. Significant correlation (p<0.01) was found between serum low density lipoprotein cholesterol (LDL-C) levels and plasma probucol concentrations in groups 3 and 5, but no correlation was found between plasma concentrations of probucol/bezafibrate and serum HDL-C levels. CETP activity in the lipoprotein-deficient plasma fraction increased in the Ch-, Ch + probucol-, and Ch + probucol and bezafibrate-fed groups (groups 2, 3 and 5, respectively), whereas a significant reduction in this activity was observed in the Ch + bezafibrate-fed group (group 4). An analysis of covariance showed that the CETP activity responded more sensitively to drug treatment than did the serum HDL-C level. CETP mRNA in liver tissue was assessed by Northern blotting at 8 weeks, but no changes were observed among the 5 groups. Probucol decreased and bezafibrate increased serum HDL-C levels, through CETP activity without affecting liver CETP mRNA levels, and the decrease in HDL-C levels produced by probucol could not be reversed by bezafibrate.

Contact leukomelanosis induced by the leaves of Piper betle L. (Piperaceae): a clinical and histopathologic survey.

BACKGROUND: In April 1997, an unusual pigmentary disorder was noticed by dermatologists in Taiwan. All patients had a history of using facial dressings with steamed leaves of Piper betle L. (Piperaceae). OBJECTIVE: Our purpose was to clarify the evolution and the origin of this unique leukomelanosis. METHODS: Fifteen patients with an unusual pigmentary disorder, who visited our clinic in September and October 1997, were asked to complete a questionnaire designed to elicit the history related to the disorder. Eight of these 15 patients underwent skin biopsies: 6 on the mottled hyperpigmented area (group A) and 2 on the hypopigmented area (group B). All 8 specimens were prepared with hematoxylin-eosin, Masson-Fontana, and S-100 stains. RESULTS: The results of the questionnaire revealed that these patients had all experienced a temporary erythematous reaction in the first few days of the use of the facial dressing, and 9 of them also complained of an accompanying stinging sensation. A bleaching effect became noticeable approximately 1 week to 1 month later. Eight patients reported that the hyperpigmentation and confetti-like hypopigmentation occurred after overexposure to the sun. In both groups, histopathologic examination revealed some melanophages in the dermis. Masson-Fontana staining of specimens from group A showed local interspersed depigmentation and hyperpigmentation in the basal epidermis and pigmentary incontinence in the dermis. This picture was different from the homogeneous depigmentation within basal epidermis in specimens from group B. In both groups, S-100 staining was negative for melanocytes in the depigmented area. CONCLUSION: The clinical course and histopathologic findings suggest that the evolution of this pigmentary disorder can be divided into 3 stages. The first stage is the immediate bleaching stage, when an irritant reaction is usually conspicuous. The second stage consists of prominent hyperpigmentation visible both grossly and microscopically. The final stage is characterized by confetti-like depigmentation. It may be induced by chemicals in the betel leaves such as phenol, catechol, and benzene derivatives, perhaps through inhibition of melanin synthesis or melanocytotoxicity.

Effects of chronic exercise on muscarinic receptor-mediated vasodilation in rats.

Previous studies have demonstrated that vascular responses to acetylcholine (ACh), an endothelium-dependent vasodilator, are enhanced in exercise-trained animals. In order to see if chronic exercise upregulates endothelial muscarinic (M) receptor, the subtype of M receptors responsible for ACh-induced vasorelaxation in the thoracic aorta of male Wistar rats was characterized first, then a receptor assay was performed. These animals were divided into exercise and control groups. The trained rats ran on a treadmill with a moderate intensity for 60 min per day, 5 days per week. After 10 weeks of training, rats were decapitated and their thoracic aortae were isolated. The subclass of M receptor in endothelium was pharmacologically identified on the basis of selective affinity of antagonists; ie, pirenzepine for M1, gallamine for M2, and 4-diphenylacetoxy-N-methylpiperidine methiodide for M3. Our results showed that in the thoracic aorta of Wistar rats, 1) ACh-induced vasorelaxation was mediated by M3 receptor; 2) chronic exercise enhanced ACh-evoked vasodilating responses. However, this alteration was not caused by receptor upregulation, as maximal binding sites and affinity of M3 receptor were not changed by chronic exercise. Other possible mechanisms need to be further studied.

[Effects of furyl-dihydropyridine I on coronary collateral circulation in myocardial infarction of dogs].

Effects of furyl-dihydropyridine I (FDP-1) on collateral circulation were observed in ischemic myocardium of dogs. FDP-1 (200 micrograms.kg-1) of intracoronary injection increased collateral flow, reduced systemic artery resistance, and coronary systolic pressure in infarcted region and the area of infarction decreased from 28.9 +/- 1.3% to 15.3 +/- 1.2% (P < 0.01, n = 6). The results indicated that FDP-1 could improve coronary collateral circulation, increase collateral flow in ischemic region, decrease collateral flow in ischemic region, decrease myocardial oxygen demand, and protect myocardial ischemia.

Blood pressure and educational level among factory workers in Ibadan, Nigeria.

An epidemiological survey of blood pressure was carried out among men employed at a single factory in Ibadan, Nigeria. All available employees participated, with only four persons excluded at the time of analysis for missing data. Hypertension was uncommon (blood pressure greater than or equal to 160/95 = 8%) and little rise in mean blood pressure was observed with age. Obesity was likewise uncommon, although body mass index was related to blood pressure (r = 0.22; P less than 0.01). Contrary to reports from Western industrialised countries, education was found to have a significant positive association with blood pressure, and this finding was independent of age, body mass index, pulse, and alcohol consumption. The process of modernisation is associated with rising blood pressure in West Africa at the present time, but the absolute risk remains low.

Oversizing of donor hearts: beneficial or detrimental?

To determine the effects of donor/recipient weight mismatch on allograft function and survival after orthotopic heart transplantation, we retrospectively compared the clinical and the hemodynamic characteristics of recipients weighing more than their donor ("undersized") with those of recipients weighing less than their donor ("oversized"). The median follow-up period was 24 months (range, 0 to 67 months). In 88 patients (59%) donor weight was 1% to 46% less than recipient weight (13.5 +/- 8.9 means +/- SD). In 61 patients (41%) donor weight exceeded recipient weight by 0% to 139% (20% +/- 23%). When recipient ideal body weight was used in the analysis, 75 patients (51%) were undersized by 1% to 59% (13% +/- 10%), and 72 patients (49%) were oversized by 0% to 67% (19% +/- 18%). Preoperative transpulmonary gradient, ventricular function, and exercise tolerance were similar in the two groups. The number and severity of episodes of rejection and infection after transplantation were also similar in the two groups 1, 6, and 12 months after transplantation. When recipient ideal weight was used in the analysis, right ventricular (RV) and left ventricular (LV) ejection fractions (EFs) were within normal limits (RVEF greater than 40%; LVEF greater than or equal to 45%) and similar in the two groups. When recipient actual weight was used in the analysis, the LVEF measured at 12 months after heart transplantation was higher in the oversized than in the undersized group (52 +/- 11 vs 46 +/- 10; p less than 0.05). Postoperative hemodynamic values and exercise tolerance were similar in the two groups regardless of whether recipient weight or ideal body weight were used in the analysis. Forty-six recipients died 0 to 46 months (median, 7 months) after orthotopic heart transplantation. In a Cox regression model, recipients with donor weight greater than recipient ideal weight had a significantly greater risk of death within the follow-up period than did recipients with donor weight less than recipient ideal weight (relative risk = 2.19; p less than 0.05). When percent donor weight/recipient ideal weight mismatch was used as a continuous variable, donor heart oversizing was negatively related to survival, independent of preoperative transpulmonary gradient values (p less than 0.05). In contrast to common belief, oversizing of donor hearts does not improve the outcome of orthotopic heart transplant recipients who have reversible preoperative pulmonary hypertension. Acceptance of undersized donor hearts is not detrimental to allograft function and recipient survival. Use of undersized donor hearts may maximize the use of critically scarce donor organs.

Bedside diagnosis of preserved versus impaired left ventricular systolic function in heart failure.

The importance of recognizing symptomatic heart failure with preserved left ventricular (LV) systolic function has only recently been appreciated. To determine its frequency and identify clinical features that make the bedside diagnosis likely, 82 patients admitted for decompensated heart failure were classified into 2 groups based on their LV systolic performance, as defined by fractional shortening (FS): group I (n = 59), with impaired systolic function (fractional shortening less than 24%), and group II (n = 23) with preserved systolic function (fractional shortening greater than or equal to 24%). Mean fractional shortening was 15 +/- 5% and 39 +/- 1% for groups I and II, respectively. Female gender (p less than 0.05), obesity (p less than 0.01) and diastolic blood pressure greater than or equal to 105 mm Hg (p less than 0.05) predominated in group II. Jugular venous distention was identified more frequently in group I (p less than 0.05). No statistically significant difference between the 2 groups was noted among various demographic variables (age, duration of symptoms, history of hypertension, ischemic heart disease and heavy alcohol drinking) or physical findings (S3 gallop, edema, cardiomegaly, pulmonary congestion and pulmonary edema). Echocardiographic mean left ventricular dimension measured 6.6 +/- 1 versus 5.0 +/- 1 cm (p less than 0.01) and mean posterior wall thickness 1.1 +/- 0.3 versus 1.4 +/- 0.4 cm (p less than 0.01) in group I and II, respectively. The combination of diastolic blood pressure greater than or equal to 105 mm Hg and an absence of jugular venous distention had a high specificity and positive predictive value (100%) for identifying group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of left ventricular hypertrophy on ventricular arrhythmias in the absence of coronary artery disease.

Left ventricular hypertrophy has a grave prognosis. Ventricular arrhythmias may account for a large portion of this poor prognosis, but the contribution of coronary artery disease has not been excluded. The occurrence of ventricular arrhythmias was investigated by 24 h ambulatory electrocardiographic (ECG) monitoring in 49 hypertensive patients who had normal findings on coronary arteriography. The presence of left ventricular hypertrophy was assessed by both ECG and echocardiography. The frequency and complexity of ventricular arrhythmias were significantly related to the presence of left ventricular hypertrophy whether it was defined by wall thickness (interventricular septum or posterior wall greater than or equal to 1.2 cm) or by left ventricular mass indexed to height (left ventricular mass/height greater than or equal to 163 g/m in men and greater than or equal to 121 g/m in women). The relation between left ventricular mass or wall thickness to ventricular arrhythmia was graded and continuous; for every 1 mm increase in the thickness of interventricular septum or posterior wall there was an associated two- to threefold increase, respectively, in the occurrence and complexity of ventricular arrhythmias. In conclusion, left ventricular hypertrophy is associated with an increase in the frequency and complexity of ventricular arrhythmias in the absence of coronary artery disease, and the relation is graded and continuous.