[An experimental study of cytology in the aqueous humor of rabbit eyes after intraocular lens implantation]

OBJECTIVE

The study was designed to count the number of white blood cells and observe their subset distribution in the aqueous humor after extracapsular lens extraction and intraocular lens (IOL) implantation in capsular bag in rabbits and to discuss the mechanism of postoperative intraocular inflammatory response.

METHODS

27 adult pigmented rabbits were divided into three groups: (1) The IOL was placed in the capsular bag after extracapsular lens extraction; (2) The extracapsular lens extraction; and (3) The control group without any surgical intervention. Aqueous humor samples were aspirated on the postoperative 1, 3, 7 and 14 days, and the total number of white blood cells in the aqueous humor and their subset distribution were counted. The data were analyzed by using analysis of variance of SAS software.

RESULTS

There was a significantly higher number of inflammatory cells in the IOL implanted eyes than that in the eyes with only extracapsular lens extraction.

CONCLUSIONS

In the early postoperative stage, there was a marked increase in the number of white blood cells and polymorphonuclear leukocytes in the IOL group, that is probably related to the mechanical ocular tissue damage and the breakdown of the blood-aqueous barrier induced by the operative procedures. There were a significant increase in the macrophages, eosinophiles, and lymphocytes in the IOL group, that suggests that an active immune response exist in the anterior ocular inflammation after IOL implantation.

MR evaluation of the brain in central diabetes insipidus

OBJECTIVE

To evaluate the role of magnetic resonance (MR) imaging in determining the cause of central diabetes insipidus (CDI) by using MR imaging to describe the findings in the hypothalamic-pituitary area in patients with CDI.

METHODS

Thirty-one cases of clinically proved CDI were prospectively studied. A control study was also conducted in 200 normal subjects. MR imaging was performed on a 1.0 T superconductive unit with T1-weighted images obtained in the sagittal, coronal and axial planes.

RESULTS

Hypothalamic-pituitary masses or structural changes were identified in 26 cases and normal structures in 5. The normal high signal intensity of the posterior pituitary lobe was absent in 29 cases, but remained unchanged in 2. In the control group, the frequency of the high signal of the posterior lobe was 93%.

CONCLUSIONS

The absence of the normal high signal in the posterior pituitary lobe is closely related to the loss of hypothalamic-pituitary function. MR imaging is very sensitive in demonstrating the changes in this area in CDI and it can provide an accurate diagnosis when combined with the clinical information.

Functional analysis of the SIS proximal element and its activating factors: regulated transcription of the c-SIS/PDGF-B gene in human erythroleukemia cells

The SIS proximal element (SPE) is essential for the basal transcription of the c-sis/PDGF-B gene as well as the lineage-specific, activated transcription of this gene seen in megakaryocytes. In gel mobility shift analyses, the SPE element forms three gel-shift complexes; the t(op) and b(ottom) complexes were detected in nuclear extracts from both untreated and phorbol 12-myristate 13-acetate ('tetradecanoylphorbol acetate', TPA) treated K562 cells, whereas the m(iddle) complex was detected only in nuclear extracts from TPA-treated K562 cells. Site-directed mutagenesis of the SPE revealed a CCACCC motif that was essential for promoter activity as well as the formation of all three SPE gel-shift complexes. Nested-deletion analyses showed that the SPE was required for TPA-inducibility of c-sis/PDGF-B transcription. Antibody supershift analyses demonstrated that the t gel-shift complex contained both Sp1 and Sp3, and that the b complex contained only Sp3. In vitro transcription assays demonstrated that both Sp1 and Sp3 could support c-sis/PDGF-B transcription independent of each other in untreated K562 cells. However, overexpression of Sp1/Sp3 failed to significantly increase the c-sis/PDGF-B transcription in K562 cells.

Experimental cascaded operation of low-birefringence nonlinear-optical loop mirrors

We experimentally demonstrate the operation of a low-birefringence (low-bi) nonlinear-optical loop mirror (NOLM) that has the advantages of low switching energy, tolerance to timing jitter, and cascadability. Because cascading two all-optical logic gates is an important step toward high-speed optical signal processing and header processing in time-division-multiplexed networks, we also demonstrate the cascaded operation of two low-bi NOLM's. Using a passively mode-locked fiber laser that produces 450-fs pulses at a wavelength of 1.55 microm, we achieve a 10.7:1 switching contrast ratio and a 2.7-pulse-widths-wide timing window after the cascaded gates. The results agree well with theoretical predictions and confirm the advantages of the long interaction length associated with orthogonally polarized pulses in low-bi (Deltan ~ 3.0 x 10(-6)) polarization-maintaining fiber.

Differential regulation of kallikrein, kininogen, and kallikrein-binding protein in arterial hypertensive rats

This study was designed to determine whether the kallikrein-kinin system exerts a protective action in hypertension induced by chronic inhibition of nitric oxide synthase. N omega-nitro-L-arginine methyl ester (L-NAME, 40 mg/100 ml water) was given orally to Sprague-Dawley rats, while controls received regular tap water. Hepatic kininogen mRNA levels in the L-NAME-treated group were 2.9- and 2.5-fold higher at 3 and 4 wk, respectively, compared with control rats, whereas kallikrein-binding protein (KBP) mRNA levels were 82% and 45% of the values found in control rats at 3 and 4 wk, respectively. There was no significant change in hepatic alpha 1-antitrypsin mRNA levels under the same conditions. At 3 and 4 wk post L-NAME treatment, renal kallikrein mRNA levels were 2.5- and 3.4-fold higher than in controls, whereas renal beta-actin mRNA levels were similar between groups. Changes in the transcript levels of renal kallikrein, kininogen, and KBP were consistent with their protein levels. Immunoreactive total kininogen and low-Mr kininogen levels in sera and tissue kallikrein levels in kidney were significantly higher in the L-NAME-treated group, whereas KBP levels in the circulation were lower compared with controls. Systolic blood pressure was increased by 58 +/- 4 mmHg after 4 wk of L-NAME treatment. This effect was enhanced in rats given L-NAME in combination with HOE-140, a bradykinin B2-receptor antagonist, at the dose of 100 micrograms/day ip (79 +/- 5 vs. 58 +/- 4 mmHg, P < 0.05). This difference was confirmed by direct measurement of mean blood pressure (MBP). An intra-arterial bolus injection of 200 ng bradykinin significantly decreased MBP of L-NAME-treated rats, and this effect was blunted in the group treated with the bradykinin antagonist (-29 +/- 3 vs. -9 +/- 2 mmHg, P < 0.01). These results suggest that enhanced kallikrein and kininogen synthesis may have a protective role against the cardiovascular effects induced by chronic inhibition of nitric oxide synthesis.

Effects of dopexamine hydrochloride on calcium channels in isolated guinea pig ventricular myocytes

The mechanisms responsible for the cardiac positive inotropic effects of dopexamine hydrochloride, a combined dopamine receptor agonist at both D1-receptors and beta 2-adrenoceptors, were studied. The calcium channel currents were recorded using whole-cell patch clamp technique in isolated guinea pig ventricular myocytes. At a holding potential of -40 mV, cells were depolarized to 0 mV for 400 ms at a frequency of 0.2 Hz. Dopexamine hydrochloride at doses of 5, 50 and 100 microM increased the verapamil-sensitive Ca2+ inward current by 109, 147 and 194%, respectively. The effects of dopexamine hydrochloride on Ca2+ current reached its maximum at 5 min and partially recovered after washout of the drugs. The increased Ca2+ current induced by dopexamine hydrochloride was completely inhibited by 20 microM propranolol, a beta-adrenoceptor antagonist, and was not antagonized by 20 microM of SCH23390, a highly selective D1-receptor antagonist. These results suggest that the cardiac positive inotropic effects of dopexamine hydrochloride are brought about by the increase of Ca2+ current via stimulation of beta 2-adrenoceptors.

Alzheimer's disease associated with mutations in presenilin 2 is rare and variably penetrant

Missense mutations in the presenilin 2 (PS-2) gene on chromosome 1 were sought by direct nucleotide sequence analysis of the open reading frame of 60 pedigrees with familial Alzheimer's disease (FAD). In the majority of these pedigrees, PS-1 and beta-amyloid precursor protein (beta APP) gene mutations had been excluded. While no additional PS-2 pathogenic mutations were detected, four silent nucleotide substitutions and alternative splicing of nucleotides 1338-1340 (Glu325) were observed. Analysis of additional members of a pedigree known to segregate a Met239Val mutation in PS-2 revealed that the age of onset of symptoms is highly variable (range 45-88 years). This variability is not attributable to differences in ApoE genotypes. These results suggest (i) that, in contrast to mutations in PS-1, mutations in PS-2 are a relatively rare cause of FAD; (ii) that other genetic or environmental factor modify the AD phenotype associated with PS-2 mutations; and (iii) that still other FAD susceptibility genes remain to be identified.

Transcriptional regulation of the SIS/PDGF-B gene in human osteosarcoma cells by the Sp family of transcription factors

Expression of PDGF-B, the gene encoding the platelet-derived growth factor B chain, has been implicated as a participant in an autocrine growth loop in the human osteosarcoma cell line U2-OS. In previous work, we identified a primary site in the PDGF-B promoter, the SIS proximal element (SPE), which is critical for transcription of the PDGF-B gene in U2-OS cells. We also identified Sp1 as one of the SPE-binding proteins in U2-OS nuclear extracts. In the present work, we have identified another SPE-binding protein to be Sp3. Gel mobility shift assays showed that both Sp1 and Sp3 require the CACCC motif within the SPE for binding. In vitro transcription assays showed that Sp1 or/and Sp3 is necessary for transcription of the PDGF-B gene. Cotransfection experiments functionally demonstrated that Sp1 and Sp3 can independently or additively activate the PDGF-B promoter through the SPE as well as a synthetic promoter. However, the CACCC motif within the SPE is not the only site within the minimal PDGF-B promoter through which Sp1/Sp3 acts; additional nested deletion analyses showed that multiple cis-acting elements within the minimal promoter are required for full level transcription of the PDGF-B gene in U2-OS cells.

Phenotypic expression of Pseudomonas syringae avr genes in E. coli is linked to the activities of the hrp-encoded secretion system

The specific recognition of elicitors produced by plant pathogenic bacteria carrying avirulence (avr) genes is postulated to initiate cellular defense responses in plants expressing corresponding resistance genes. The biochemical functions of most avr genes, however, are not known. A heterologous system was developed to phenotypically express Pseudomonas syringae avr genes in Escherichia coli cells that required the P. syringae hrp cluster. E. coli MC4100 transformants carrying the plasmic-borne P. syringae pv. syringae Pss61 hrp cluster and p. syringae pv. glycinea avrB expressed from a triple lacUV5 promoter gained the ability to elicit the hypersensitive response in soybean cultivars expressing Rpg1 and in an Arabidopsis thaliana accession expressing RPM1. Inactivation of energy transducing or outer membrane components of the hrp-encoded secretion system blocked phenotypic expression expression of avrB in E. coli, but deletions abolishing harpinPSS production had little effect on the production of the AvrB phenotype by the E. coli transformants. Phenotypic expression of avrA, AvrPto, avrRpm1, avrRpt2, and avrPph3 in E. coli was also shown to require the hrp cluster. The results indicate that generation of the Avr phenotype in P. syringae strains is specifically dependent on the secretion activities of the hrp cluster.

Glucose metabolism and insulin release in mouse beta HC9 cells, as model for wild-type pancreatic beta-cells

Glucose metabolism and its relationship with glucose-induced insulin release were studied in beta HC9 and beta TC3 cells to identify and characterize key factors controlling the intermediary metabolism of glucose and glucose-induced insulin release. The beta HC9 cell line, derived from pancreatic islets with beta-cell hyperplasia, is characterized by a normal concentration-dependency curve for glucose-stimulated insulin release, whereas the beta TC3 cell line, derived from pancreatic beta-cell tumors, shows a marked leftward shift of this curve. Maximum velocity and the Michaelis-Menten constant of glucose uptake in beta HC9 and beta TC3 cells were similar, even though GLUT-2 expression in these two cell lines differed. In both cell lines, the kinetic characteristics of glucose usage, glucose oxidation, and glucose-induced oxygen consumption were similar to those of glucose phosphorylation, indicating that the kinetics of glucose metabolism from the glucose phosphorylation step in the cytosol to the mitochondrial process of oxidative phosphorylation are determined by the glucose-phosphorylating enzyme, that is, by glucokinase in beta HC9 cells and by hexokinase in beta TC3 cells. Thus beta HC9 cells provide an opportunity for the quantitative analysis of glucose metabolism, the associated generation of coupling factors, and other essential beta-cell functions involved in glucose sensing and insulin secretion.

Molecular recognition with C-clamp porphyrins: synthesis, structural, and complexation studies

Porphyrin-based molecular clefts equipped with a strategically positioned carboxylic group have been synthesized. These ditopic porphyrins exhibit excellent binding affinity for many neutral substrates. X-ray structures of a porphyrin-water inclusion complex and a Zn(porphyrin)-methanol complex reveal how the carboxylic group interacts with substrates via H-bonding. Multipoint recognition is demonstrated in the differential binding of 1,2,3- versus 1,2,4-triazole, suggesting the possible use of such receptors to separate heterocyclic bases.

Dual-slice spiral versus single-slice spiral scanning: comparison of the physical performance of two computed tomography scanners

In this paper we deal with two types of spiral scanners; one is a single-slice spiral scanner, while the other employs dual-slice technology into spiral scanning. Physical performance parameters, including image noise, contrast resolution, spatial resolution (transversal and longitudinal), and radiation exposure are measured. Computer simulations based on two interpolation methods (180 degrees and 360 degrees linear interpolation) are also used in evaluating the slice-sensitivity profile (SSP) and noise. The results show that the noise behaves in the same way for both types of scanners. The noise change, relative to that of the standard scan with the same scanning parameters, depends solely on the interpolation algorithm. Table speed and scanner geometry (either single slice or dual slice) have no effect on the noise value. For the given table speed, as well as individual detector collimation (slice width) the dual-slice scan results in better longitudinal resolution (SSP) compared to a single-slice scan if the scan is obtained with nonoverlapping slices (pitch greater than 2). This is because the dual-slice scan obtains twice the number of nonoverlapped projections for the same length, which reduces the degradation of the slice profile by using more densely arranged projections (in the longitudinal direction) for the interpolation. In the dual-slice scanner the workable scan rate is extended up to pitch 4 compared to a pitch of 2 for the single-slice scanner. Therefore, the dual-slice spiral scanner is preferred in applications requiring an increased scan rate with comparative image quality.

[A pathological study of goat multiple organ failure model]

We succeeded in replication a standardized goat model of multiple organ failure (MOF). In the experimentation, the animals were monitored and supported with facilities pertaining to a human intensive care unit, with constant infusion of LPS into portal vein following trauma and hemorrhagic shock. The main organs of MOF goats were observated by the light microscopy and electronmicroscopy, including the lungs, hearts, livers, kidneys, intestines and spleens. The results showed that there were some areas of spotty and mass necrosis in the organ parenchyma with inflammatory cell infiltration. Our studies suggested that once the clinical multiple organ failure, severe pathological changs occur in organs.

[Protective effect of verapamil on light-induced rat retinopathy]

OBJECTIVE

In order to search for simple and effective medicine to protect light-induced retinopathy.

METHOD

We used verapamil as a protective agent. We measured the contents of the end product of lipid peroxidation, malondialdehyde (MDA), in the rat retinas immediately, 4 days, 15 days and 30 days after the damage in the damaged group and protective group, and observed their histopathologic structures and the integrity of the outer blood-retinal barrier.

RESULTS

The results showed that the content of MDA in the normal retina was 0.36 +/- 0.07 nmol/mg, while in the damaged group the MDA levels at different times were 0.52 +/- 0.03 nmol/mg, 0.70 +/- 0.20 nmol/mg, 0.52+/- 0.07 nmol/mg, and 0.47 +/- 0.03 nmol/mg respectively, being significantly different from that of the normal group. In the protective group, the MDA levels at different times were 0.40 +/- 0.04 nmol/mg, 0.49 +/- 0.03 nmol/mg, 0.40 +/- 0.05 nmol/mg and 0.39 +/- 0.08 nmol/mg respectively, being significantly different from that in the damaged group at the corresponding times. In the damaged group, the histologic study showed that the retinal structures were damaged in various degrees at 4 days and most severely at 15 days after light exposure and the outer blood-retinal barrier was also damaged, while in the protective group no significant pathologic changes of retina were seen.

CONCLUSION

Verapamil is an effective protective medicine for light-induced retinopathy.

Failure to detect missense mutations in the S182 gene in a series of late-onset Alzheimer's disease cases

The possibility of an interaction of multiple genes has been speculated in pathogenesis of Alzheimer's disease (AD). Because we have recently cloned a novel gene S182 bearing five different missense mutations which segregate with early-onset familial AD, we sought the frequency of these mutations in familial and sporadic late-onset AD to clarify the incidence of these mutations in the disease. The current study showed lack of these mutations in 118 independent subjects affected with late-onset Alzheimer's disease.

[Correlation between p53 nuclear protein accumulation and mutations of the p53 gene in human esophageal cancer from linxian]

Thirty-three esophageal tumors were analyzed by immunohistochemistry for P53 nuclear protein accumulation, and the results were compared to p53 gene mutations by PCR-direct sequence analysis. A highly significant correlation between the presence of p53 mutations and p53 nuclear protein accumulation was found. Of 33 tumors, 23 (69.7%) that demonstrated P53 protein expression 12(36%) had p53 mutations. Of 12 tumors with p53 mutations, 9 tumors showed P53 intensive nuclear reactivity. The results reported here are consistent with the idea that p53 mutations may be an important biological event in esophageal cancer progression and P53 expression was correlated with p53 gene mutation.

Irreversible binding kinetics of Bacillus thuringiensis CryIA delta-endotoxins to gypsy moth brush border membrane vesicles is directly correlated to toxicity

To examine the binding of Bacillus thuringiensis delta-endotoxins, CryIAa, CryIAb, and CryIAc, to Lymantria dispar (gypsy moth) brush border membrane vesicles (BBMV), saturation kinetic analyses were conducted according to a two-step interaction scheme [formula: see text] for delta-endotoxin binding to BBMV, rather than the one-step reversible binding presented in prior reports. The order of toxicity of the delta-endotoxins, as measured by the dose required for a 50% inhibition of weight gain (ID50), was CryIAa (77.3 ng) > CryIAb (157 ng) > CryIAc (187 ng). While both the maximum extent of binding, Bmax, and the half-maximum insertion rate concentration, K1/2, was observed to be indirectly related to toxicity, the rate constant of irreversible binding, k2, was found to be directly correlated to toxicity.

Sudden coronary death. Frequency of active coronary lesions, inactive coronary lesions, and myocardial infarction

BACKGROUND

The reported frequency of active coronary lesions (plaque rupture and coronary thrombosis) in sudden death due to coronary artery atherosclerosis (sudden coronary death) has varied from < 20% to > 80% of cases in previous series. In hearts lacking an active coronary lesion, sudden death has usually been attributed to a healed myocardial infarction. The purpose of the present study was to determine the frequency of active and inactive coronary lesions and myocardial infarction in individuals with sudden coronary death.

METHODS AND RESULTS

The hearts of persons who died as a result of sudden coronary death underwent perfusion-fixation and postmortem angiography. An active coronary lesion was defined as a disrupted plaque, luminal fibrin/platelet thrombus, or both. We defined an inactive lesion as having a cross-sectional luminal stenosis of > or = 75% with neither plaque disruption nor luminal thrombus. Ninety hearts were examined (from 72 men and 18 women; mean age at the time of death, 51 +/- 10 years). Acute myocardial infarction was present in 19 (21% [acute myocardial infarction only in 9, both acute and healed myocardial infarction in 10]), healed myocardial infarction only in 37 (41%), and no myocardial infarction in 34 (38%). Active coronary lesions were identified in 51 (57%): acute thrombi plus disrupted plaques in 27, acute thrombi only in 21, and disrupted plaques only in 3. In hearts with acute myocardial infarction, active coronary lesions were significantly more prevalent than in hearts with only healed myocardial infarction or hearts lacking an acute or a healed myocardial infarction (89%, 46%, and 50%, respectively; P < .005). Hearts without acute or healed myocardial infarction and without active lesions were similar to hearts with active lesions with respect to heart weight and severity of epicardial coronary disease.

CONCLUSIONS

Acute changes in coronary plaque morphology (thrombus, plaque disruption, or both) were found in 57% of cases of sudden coronary death. In hearts with myocardial scars and no acute infarction, active coronary lesions were identified in 46% of cases. Neither myocardial infarction (acute or healed) nor an active coronary lesion was present in 19% of hearts.

Familial Alzheimer's disease in kindreds with missense mutations in a gene on chromosome 1 related to the Alzheimer's disease type 3 gene

We report the cloning of a novel gene (E5-1) encoded on chromosome 1 which has substantial nucleotide and amino-acid sequence similarity to the S182 gene on chromosome 14q24.3. Mutations, including three new missense mutations in the S182 gene, are associated with the AD3 subtype of early-onset familial Alzheimer's disease (AD). Both the E5-1 and the S182 proteins are predicted to be integral membrane proteins with seven membrane-spanning domains, and a large exposed loop between the sixth and seventh transmembrane domains. Analysis of the nucleotide sequence of the open reading frame (ORF) of the E5-1 gene led to the discovery of two missense substitutions at conserved amino-acid residues in affected members of pedigrees with a form of familial AD that has a later age of onset than the AD3 subtype (50-70 years versus 30-60 years for AD3). These observations imply that the E5-1 gene on chromosome 1 and the S182 gene on chromosome 14q24.3 are members of a family of genes (presenilins) with related functions, and indicates that mutations in conserved residues of E5-1 could also play a role in the genesis of AD. Our results also indicate that still other AD susceptibility genes exist.

Evaluation of PAPNET system for rescreening of negative cervical smears

We rescreened 2,238 cervicovaginal smears conventionally prepared with Papanicolaou stain by PAPNET system. The slides screened manually as negative, were sent to PAPNET system. The image tapes were reviewed on a high-resolution monitor, and categorized as negative, unsatisfactory, and atypical. All atypical cases were rescreened manually. Abnormal cases were reviewed by a cytopathologist. Two-thousand one hundred and two (94%) cases rescreened by PAPNET were negative. Nine of 45 unsatisfactory cases by PAPNET were unsatisfactory by manual review. Ninety-one (4.0%) cases by PAPNET were atypical. On manual rescreening, 86 of 91 were negative, 20% showing benign cellular changes; five of 91 were atypical, the atypia, however, not exceeding low-grade category. The detection rate by PAPNET method was 0.2% (five of 2,238 cases). We conclude: 1) In a cytology laboratory with good quality control, PAPNET rescreening does not significantly increase the detection rate. 2) For cytology laboratories without in-house rescreening, PAPNET offers an alternative at a price. 3) The PAPNET system also offers a tool by which a laboratory can occasionally monitor its performance. 4) The cost benefit analysis of the system requires further study and scrutiny.

Variable effects of maturity-onset-diabetes-of-youth (MODY)-associated glucokinase mutations on substrate interactions and stability of the enzyme

Mutations in the human glucokinase (GK) gene are thought to cause maturity-onset diabetes of youth (MODY) by leading to the production of enzymes with reduced catalytic activities and increased glucose Km values. However, in some cases the diabetic phenotype is more severe than might be predicted from these apparent kinetic effects alone. To determine whether these mutations might also effect other characteristics of the enzyme, nine MODY-associated mutants were expressed as fusion proteins with Schistosoma japonicum glutathione S-transferase (GST) and compared with three wild-type human GK isoforms that were also expressed in the same manner. Three GST-GK isoforms (liver 1, liver 2 and islet) were kinetically indistinguishable from each other and from purified rat liver GK. Noteworthy is a glucose-induced fit effect for the interaction of trinitrophenyl (TNP)-ATP with GST-GK, whereby glucose significantly increased the affinity of TNP-ATP binding to GST-GK without changing the stoichiometry of binding. The nine MODY-associated mutations studied either showed diminished catalytic activity, substrate affinities, allosteric regulation, or stability of the fusion enzyme. We conclude that: (1) Gly261 and Lys414 are important for ATP binding; (2) Val203 may be essential for a glucose-induced fit effect; and (3) the stability of fusion protein may be significantly reduced when Glu300 is replaced by Lys. These results suggest that, in addition to effects on the Km and Vmax. of GK, a decrease in the ATP-binding affinity or stability of the mutated enzyme may also contribute to a reduction of GK activity in individuals with GK-MODY. In the B-cell this would have the effect of blunting glucose-stimulated insulin release, thereby contributing to the diabetic phenotype.

Evidence for inter-generational instability in the CAG repeat in the MJD1 gene and for conserved haplotypes at flanking markers amongst Japanese and Caucasian subjects with Machado-Joseph disease

The size of the (CAG)n repeat array in the 3' end of the MJD1 gene and the haplotype at a series of microsatellite markers surrounding the MJD1 gene were examined in a large cohort of Japanese and Caucasian subjects affected with Machado-Joseph disease (MJD). Our data provide five novel observations. First, MJD is associated with expansion fo the array from the normal range of 14-37 repeats to 68-84 repeats in most Japanese and Caucasian subjects, but no subjects were observed with expansions intermediate in size between those of the normal and MJD affected groups. Second, the expanded allele associated with MJD displays inter-generational instability, particularly in male meioses, and this instability was associated with the clinical phenomenon of anticipation. Third, the size of the expanded allele is not only inversely correlated with the age-of-onset of MJD (r = -0.738, p < 0.001), but is also correlated with the frequency of other clinical features [e.g. pseudoexophthalmos and pyramidal signs were more frequent in subjects with large repeats (p < 0.001 and p < 0.05 respectively)]. Fourth, the disease phenotype is significantly more severe and had an early age of onset (16 years) in a subject homozygous for the expanded allele, which contrasts with Huntington disease and suggests that the expanded allele in the MJD1 gene could exert its effect either by a dominant negative effect (putatively excluded in HD) or by a gain of function effect as proposed for HD. Finally, Japanese and Caucasian subjects affected with MJD share haplotypes at several markers surrounding the MJD1 gene, which are uncommon in the normal Japanese and Caucasian population, and which suggests the existence either of common founders in these populations or of chromosomes susceptible to pathologic expansion of the CAG repeat in the MJD1 gene.