Spinal cord swelling as a myelographic indicator of prognosis: a retrospective study in dogs with intervertebral disc disease and loss of deep pain perception

The association of myelographic spinal cord swelling with neurological outcome was examined in 46 dogs with intervertebral disc disease and absence of deep pain perception (DPP). Spinal cord swelling was measured by calculating a ratio of the length of the loss of the myelographic dye column to the length of the second lumbar vertebra (L2). A positive neurological outcome was defined as return of voluntary motor function. A cut-off value for swelling:L2 of 5.0 was established by the creation of a receiver operator characteristic curve. Using a swelling:L2 ratio of 5.0 as a cutoff for indication of neurological recovery yielded a sensitivity of 74% and a specificity of 61%. Overall neurological recovery rate was 43%. Dogs with spinal cord swelling:L2 ratios less than 5.0 had a recovery rate of 61%, whereas dogs with a ratio greater than or equal to 5.0 had a recovery rate of 26%. Evaluation of these data by chi square analysis confirmed that a ratio less than 5.0 was associated with a positive outcome, and a ratio greater than or equal to 5.0 was associated with a negative outcome, (P < .05). Although other factors, such as duration of neurological signs, affect neurological outcome in dogs with no DPP, evaluation of myelographic spinal cord swelling can assist in establishing a prognosis.

Short communication: portal imaging with film-cassette combinations: what film should we use?

A large number of commercially available X-ray films were obtained to assess their suitability for megavoltage radiotherapy portal imaging. The speed (represented by optimum film dose), gamma (gamma) and latitude of all these films were determined. Films with high gamma values are recommended for clinical use to maximize the low levels of radiation contrast produced by a megavoltage beam.

Novel proteins with binding specificity for DNA CTG repeats and RNA CUG repeats: implications for myotonic dystrophy

While an unstable CTG triplet repeat expansion is responsible for myotonic dystrophy, the mechanism whereby this genetic defect induces the disease remains unknown. To detect proteins binding to CTG triplet repeats, we performed bandshift analysis using as probes double-stranded DNA fragments having CTG repeats [ds(CTG)6-10] and single-stranded oligonucleotides having CTG repeats ss(CTG)8 or RNA CUG triplet repeats (CUG)8. The source of protein was nuclear and cytoplasmic extracts of HeLa cells, fibroblasts and myotubes. Proteins binding to the double-stranded DNA repeat [ds(CTG)6-10], were inhibited by nonlabeled ds(CTG)6-10, but not by a non-specific DNA fragment (USF/AD-ML). Another protein binding to ssCTG probe and RNA CUG probe was inhibited by nonlabeled (CTG)8 and (CUG)8. Nonlabeled oligos with different triplet repeat sequences, ss(CAG)8 or ss(CGG)8, did not inhibit binding to the ss(CTG)8 probe. However, when labeled as probes, the (CAG)8 and (CGG)8 bound to proteins distinct from the CTG proteins and binding was inhibited by nonlabeled (CAG)8 or (CGG)8 respectively. The protein binding only to the RNA repeat (CUG)8 was inhibited by nonlabeled (CUG)8 but not by nonlabeled single- or double-stranded CTG repeats. Furthermore, the CUG-BP exhibited no binding to an RNA oligonucleotide of triplet repeats of the same length but having a different sequence, CGG. The CUG binding protein was localized to the cytoplasm, whereas dsDNA binding proteins were localized to the nuclear extract. Thus, several trinucleotide binding proteins exist and their specificity is determined by the triplet sequence. The novel protein, CUG-BP, is particularly interesting since it binds to triplet repeats known to be present in myotonin protein kinase mRNA which is responsible for myotonic dystrophy.

Expression of brain-type creatine kinase and ubiquitous mitochondrial creatine kinase in the fetal rat brain: evidence for a nuclear energy shuttle

To test the hypothesis that embryonic brain cells utilize a creatine phosphate energy shuttle, we examined the pattern of creatine kinase (CK) isoform expression and localization in the fetal rat brain. Moderate levels of CK activity are present at embryonic day 14 (7 U/mg protein) and decrease slightly until 3 days postpartum followed by a rapid, fourfold up-regulation to adult levels by 1 month (18 U/mg protein). In parallel with changes in enzyme activity, there is a biphasic and coordinate pattern of expression of brain-type CK (BCK) and ubiquitous mitochondrial CK (uMtCK) determined by nondenaturing electrophoresis and immunoblot analysis. The localization of CK isoforms was examined by immunocytochemistry, and, during the fetal period, BCK and uMtCK immunoreactivity was detected throughout the central and peripheral nervous system, especially in neuroepithelial regions of the cerebral vesicles and spinal cord. In large cells within the olfactory neuroepithelium and ventral spinal cord, differential compartmentation of CK isoforms was evident, with BCK localized primarily in cell nuclei, whereas uMtCK immunoreactivity was present in the cell body (but not within nuclei). In olfactory bulb neuroepithelium, both isoforms were expressed in the middle zone of the germinal layer associated with DNA synthesis. In embryonic skeletal and cardiac muscle, which also express BCK, the same compartmentation of BCK was seen, with BCK localized primarily in the cell nucleus of cardiac and skeletal myoblasts. These results demonstrate a coordinate pattern of expression and compartmentation of BCK and uMtCK isoforms in the fetal brain that, in some cells, provides the anatomic basis for a nuclear energy shuttle.

Psychological factors in the relationship between alcohol and cardiovascular morbidity

Most major studies have found a U-shaped relationship between the level of alcohol consumption and all cause mortality, largely as a consequence of lower death rates from coronary heart disease (CHD) amongst moderate drinkers. Previous attempts to unravel the significance of this observation have focused on controlling for possible confounders, such as smoking, social class and the existence of previous ill-health in the group of abstainers. Our analysis of data from the Whitehall II study of British Civil Servants sought to determine whether psychological factors (GHQ, Hostility, Affect Balance, Social Supports) may be influencing the observed relationships between levels of alcohol consumption and some of the established risk factors for CHD. We found evidence of weak confounding only with respect to levels of apolipoprotein B (APoB) and as such have failed to provide compelling evidence that the U-shaped relationship between alcohol and CHD mortality could be easily explained by psychosocial confounding. At the same time we would not claim that the measures we have used are either flawless or exhaust the range of psychological variables that might plausibly influence physiological mediators of cardiovascular disease.

Radiological evidence of constipation in urinary tract infection

Little objective evidence has been published to support the claim that constipation is an important contributory factor in recurrent urinary tract infection (UTI) in childhood. Using a radiological scoring system, two observers assessed faecal loading from abdominal radiographs of children with proved UTIs. There was a significant increase in the degree of faecal loading in children with UTI when compared with controls (r = 0.237). This difference was mainly accounted for by girls with recurrent (greater than five) UTIs. This study confirms an association between recurrent UTI and faecal loading. Further studies are needed to establish if there is a causal relationship and benefits from treatment.

Genetic heterogeneity in familial dilated cardiomyopathy

Familial dilated cardiomyopathy (FDCM), an inherited primary form of myocardial disease, is a significant cause of morbidity and mortality at all ages and the leading reason for cardiac transplantation worldwide. Although typically inherited as an autosomal dominant disorder, all forms of inheritance have been recognized. FDCM appears to be responsible for approximately 20-30% of all cases of dilated cardiomyopathy, the most common form of cardiomyopathy. Recently, two families having autosomal dominant FDCM were mapped. The first family had conduction abnormalities and FDCM and was mapped to 1p1-1q1, while the second family, which had pure FDCM, was mapped to 9q13-q22. Neither gene has been identified to date. In this report, one family with pure FDCM was analyzed for linkage to the 1p1-1q1 and 9q13-q22 loci using parameteric linkage analysis, with linkage to both regions excluded. This demonstrates that the pure form of FDCM is caused by multiple different genes, i.e., genetic heterogeneity. Identification of large families with FDCM will be required to identify the various genes responsible for this important clinical entity.

Precision and accuracy of clinical and radiological signs in premature infants at risk of patent ductus arteriosus

OBJECTIVE

To determine the precision (interobserver agreement) and accuracy (agreement with criterion standard) of clinical and radiological signs in premature infants at risk of patent ductus arteriosus (PDA) with left-to-right shunting.

DESIGN

Masked comparison of clinical and radiological examination with Doppler flow echocardiography (criterion standard).

SETTING

Neonatal intensive care unit.

PATIENTS

One hundred infants with birth weights less than 1750 g were studied once between days 3 and 7 of life. A third of the cohort was intubated at the time of study.

INTERVENTION

Five independent observers noted the presence or absence of an increased pulse volume, an active precordium, a heart murmur, a cardiothoracic ratio greater than 60%, increased pulmonary vascular markings on a concurrent chest x-ray film, and a relative increase of the cardiothoracic ratio compared with that from the previous chest x-ray film. Pulsed and color flow Doppler echocardiography was performed within 4 hours. All 100 tapes were reviewed by a second pediatric cardiologist.

RESULTS

Twenty-three infants had a PDA with left-to-right shunting. The precision of clinical signs was modest, with average kappa values of 0.15 for pulse volume, 0.32 for precordium, and 0.41 for murmur. Pulse quality (43%) and murmur (42%) had the highest mean sensitivities. Corresponding specificities were 74% for pulse volume and 87% for murmur. The combination of a cardiac murmur with an abnormal pulse volume had the highest positive predictive value (77%). The radiological examination did not improve the observers' ability to distinguish between patients with and without PDA.

CONCLUSIONS

The precision and accuracy of clinical and radiological signs of a PDA with left-to-right shunting are unsatisfactory. Therefore, Doppler flow echocardiography is required to diagnose PDA confidently in preterm infants between days 3 and 7 of life.

Angiotensin-I converting enzyme genotypes and left ventricular hypertrophy in patients with hypertrophic cardiomyopathy

BACKGROUND

The variability of the phenotypic expression of left ventricular hypertrophy (LVH) in patients with hypertrophic cardiomyopathy (HCM) indicates a potential role for additional modifying genes. Variants of angiotensin-I converting enzyme (ACE) gene have been implicated in cardiac hypertrophy. To assess whether ACE genotypes influence the phenotypic expression of hypertrophy, we determined the left ventricular mass index (LVMI) and extent of hypertrophy in 183 patients with HCM.

METHODS AND RESULTS

LVMI was derived by the area-length method using two-dimensional echocardiograms. Extent of LVH was determined by a point score method (1 to 10 points). DNA was extracted from blood, and ACE genotyping was performed by polymerase chain reaction (PCR) with an established protocol. Amplification of DNA in the region of polymorphism by PCR of alleles I and D showed 490- and 190-bp products, respectively. ACE genotypes DD, ID, and II were present in 60, 90, and 33 patients with HCM, respectively. In genetically independent patients (n = 108), the mean LVMI (g/m2) was 148 +/- 35.3 in those with DD (n = 35) and 134.2 +/- 33.3 in those with ID and II (n = 73) genotypes (P = .046). LVH score was 6.69 +/- 1.71 in patients with DD and 5.55 +/- 2.19 in those with ID and II genotypes (P = .004). Regression analysis showed that ACE genotypes accounted for 3.7% and 6.5% of the variability of LVMI and LVH score (P = .046 and P = .008, respectively). In 26 patients from a single family, LVMI and LVH score were also greater in patients with DD than in those with ID and II genotypes. ACE genotypes accounted for 14.7% and 10.4% of the variability of the LVMI and extent of hypertrophy, respectively.

CONCLUSIONS

ACE genotypes influence the phenotypic expression of hypertrophy in HCM.

Molecular genetics: cardiac disease and risk-related genes

Molecular genetics is playing an increasing role in the diagnosis, treatment, and prevention of cardiac disease. Moreover, most of the genes that may cause cardiac disease or predispose an individual to cardiac disease are anticipated to be identified within the next 10 years. Several genes with risk for heart disease have been identified, such as the ACE genotype DD. Replacement gene therapy as well as use of promoter-specific drugs to act on genetic regulatory elements will encompass the future treatment of cardiovascular disease. This article provides a summary of the potential roles of genetic screening for cardiac risk factors and genetic interventions in cardiovascular disease.

Objectives and prerequisites to success for integrated patient records

The concept of integrated patient-based records at first sight looks logical and consumer orientated, but it cuts across traditional record-keeping practice. This paper draws from four different fruitful initiatives to identify benefits and success prerequisites.

Expression of a mutation causing hypertrophic cardiomyopathy disrupts sarcomere assembly in adult feline cardiac myocytes

Mutations in the beta-myosin heavy chain (beta MyHC) induce hypertrophic cardiomyopathy (HCM), cardiac hypertrophy, and sarcomere disarray, with the latter being the characteristic hallmark. Thus, we sought to determine whether expression of mutant beta MyHC in adult feline cardiac myocytes, a species known to develop HCM with a phenotype identical to that in humans, induces sarcomere disarray. A full-length beta MyHC cDNA was cloned from a human heart cDNA library, and an HCM-causing mutation (Arg403Gln) was induced in the beta MyHC cDNA by site-directed mutagenesis using polymerase chain reaction (PCR). The normal and mutant beta MyHC cDNAs were cloned into p delta E1spIB shuttle vector, downstream from a cytomegalovirus (CMV) promoter. Replication-deficient recombinant adenoviral constructs (Ad5/CMV/beta MyHC-N and Ad5/CMV/beta MyHC-403) were generated through homologous recombination of p delta E1spIB/CMV/beta MyHC-N or Ad5/CMV/beta MyHC-403 and pBHG10 after cotransfection in 293 host cells. Infection of COS-1 cells with the beta MyHC construct resulted in the expression of a full-length myosin protein. Efficiency of infection of isolated adult cardiac myocytes was > 95%. Expression of the beta MyHC constructs into mRNA at 48 hours after infection of feline cardiac myocytes was confirmed by reverse transcription-PCR. The net total protein and beta-myosin synthesis were determined by using the amount of incorporation of [3H]phenylalanine into total protein and beta-myosin, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Early discharge after acute myocardial infarction: risks and benefits

BACKGROUND

Thrombolytic treatment reduces mortality in patients with acute myocardial infarction but is associated with recurrent thrombotic events after admission, and it is unclear whether current practices of early hospital discharge are safe. Timing of first major adverse events (death, reinfarction, unstable angina, secondary ventricular fibrillation) in the early post-infarction period was studied to determine the risks.

DESIGN

Follow up study.

PATIENTS

608 consecutive patients (447 men and 161 women) with confirmed myocardial infarction who were admitted to the coronary care unit of a district general hospital between January 1989 and December 1991. Clinical details, including the development of left ventricular failure and in hospital adverse events, were recorded prospectively. Follow up for out of hospital adverse events was carried out by review of the case notes, postal questionnaire, and where necessary, by telephone contact with the patient and his general practitioner.

RESULTS

The risk (95% confidence interval) of major adverse events in the first 10 days was 32.3% (26.3 to 39.4%) in patients with heart failure and 7.3% (5.1 to 9.2%) in those without. Smoothed estimates of the event rate in patients without heart failure decreased from 5.9 events/1000 persons/day on day 6 to 3.4 events/1000 persons/day on day 10 and 0.9 events/1000 persons/day on day 21. The corresponding cumulative risk estimates suggest that about 11 in every 1000 patients suffer a major, but often unpreventable, adverse event on day 6 or 7 after admission, and 23 in every 1000 do so between days 6 and 10.

CONCLUSIONS

The point at which the risk to the individual becomes acceptably low is a matter of judgement, but the risk of a major adverse event declines rapidly after a heart attack, and particularly for patients without heart failure discharge within a few days may be appropriate. Prolonging stay unnecessarily may use resources which could be more effectively used to treat cardiac disease in other ways.

Genomic organization of the human dystrophin gene across the major deletion hot spot and the 3' region

The genomic organization of most of the human dystrophin gene has not been defined at single-exon level, owing to its enormous size (2300 kb). By taking advantage of a YAC-based restriction map of the gene previously constructed, we have localized individual dystrophin exons from 42 to 79 along the central and 3' regions of the gene. These data elucidate the general organization of this large portion of the gene (1250 kb) and, in particular, characterize the genomic region most frequently involved in deletion mutations responsible for Duchenne and Becker muscular dystrophies.

Molecular and clinical aspects of inherited cardiomyopathies

Hypertrophic cardiomyopathy (HCM) is phenotypically and genotypically a heterogeneous disease. Since 1989, four chromosomal loci have been identified for HCM and the genes residing on three of these have been identified as beta-myosin heavy chain (beta-MHC), cardiac troponin-T and alpha-tropomyosin. These genes code for sarcomeric proteins and exhibit the same phenotype, suggesting that HCM is a disease of the sarcomere. Over 40 missense mutations and one deletion of the beta-MHC gene have been identified. Similarly, missense mutations in the alpha-tropomyosin gene and the cardiac troponin-T gene have been identified. From genetic studies, including de novo mutations, it is established that these mutations are indeed responsible for HCM. The molecular basis of the pathogenesis of the cardiac hypertrophy appears to be a compensatory response to the primary defect. In addition to providing a definitive presymptomatic diagnosis, studies correlating beta-MHC mutations with clinical prognosis suggest they have significant predictive value and can be helpful in genetic counselling and medical management. Dilated cardiomiopathies (DCM), the most common form of cardiomyopathies, have an estimated prevalence of nearly 40 per 100,000 individuals, and are the most common cause for cardiac transplantation in the United States. Familial dilated cardiomyopathy is thought to account for approximately 20% of the so-called cases of idiopathic DCM.

Angiotensin-I converting enzyme genotype DD is a risk factor for coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is a polygenic disease whose phenotypic manifestation is due to interaction of a number of environmental factors with an underlying genetic background. A number of genes, including the angiotensin-I converting enzyme (ACE) gene, have been implicated in the pathogenesis of CAD. ACE can affect oxidation of LDL, endothelial cell function, and smooth muscle cell migration and proliferation: all important components of atherosclerosis. A variant of ACE gene, genotype DD is associated with a higher plasma level of ACE and an increased risk of myocardial infarction, and cardiomyopathies. In this study, we sought to determine the distribution of ACE genotypes and the frequency of allele D in patients with CAD undergoing coronary angioplasty.

METHODS

DNA from 182 white patients undergoing coronary angioplasty and 338 apparently healthy white individuals was amplified by polymerase chain reaction (PCR) in the region of the polymorphism using the previously published protocol.

RESULTS

PCR amplification of alleles I and D resulted in 490 bp and 190 bp products, respectively. ACE genotype DD was present in 47% of patients with CAD as compared to 30% in the general population (p = 0.0002, Odds ratio 2.7). The frequency of allele D was 0.68 in patients with CAD and 0.55 in general population, respectively (p < 0.0001). Genotype DD was associated with CAD only in males (54% vs. 30%, p = 0.0001, Odds ratio 2.0), but not in female patients. There was no association between the frequency of ACE genotype DD and the prior history of myocardial infarction, or the extent of CAD. The frequency of ACE genotype DD was the highest among patients with restenosis following angioplasty (55%), however, the difference was not significantly changed as compared to those without restenosis (40%).

CONCLUSIONS

ACE genotype DD is more common in patients with CAD as compared to the general population, indicating that genotype DD is a genetic risk factor for CAD.

Cor triatriatum: unusual cause of transient ischaemic attacks in a 67-year-old man

Cor triatriatum is a rare congenital cardiac malformation, and in its most common form is characterised by a membrane that separates the left atrium into a proximal and distal chamber. First manifestation in adulthood has been reported previously, but at 67 years of age this patient is one of the oldest to present for the first time. It was diagnosed after a probable TIA, episodic vertigo and central retinal artery occlusion. The value of echocardiography in patients with neurological disease of presumed embolic origin is demonstrated here.

Sudden cardiac death in hypertrophic cardiomyopathy. Variability in phenotypic expression of beta-myosin heavy chain mutations

BACKGROUND

Recent identification of mutations in the beta-myosin heavy chain gene (MYH7), a major responsible gene for HCM, has provided the opportunity to characterize genotype-phenotype correlation in HCM families. In this study we analysed the phenotypic expression of two beta-myosin heavy chain (beta MHC) mutations in three unrelated HCM families.

METHODS

Living individuals from three unrelated HCM families (Families 1, 2, and 3) were screened by history, physical examination, electrocardiography, and two-dimensional echocardiography. Blood was collected from all individuals for DNA extraction. Polymerase chain reaction (PCR), restriction endonuclease digestion and chemical cleavage were utilized for detection of mutations. All mutations were confirmed by sequence analysis.

RESULTS

Identification of mutations: A missense mutation in exon 13 of the beta MHC gene (Arg403 Gln) was detected in HCM patients from Families 1 and 2. PCR amplification of the exon 13 DNA, followed by Ddel digestion of the PCR product and gel electrophoresis, showed two fragments of 84 and 70 bp in normal individuals and four fragments of 84, 70, 52 and 32 bp in HCM patients. Sequence analysis showed substitution of an adenine for guanine at coding position 1208. In Family 3, a missense mutation in exon 16 of the beta MHC gene (Val606 Met) was detected in HCM patients. Chemical cleavage of the PCR products showed an uncleaved product of 337 bp in the normal individuals, while in the affected individuals, in addition to the uncleaved product, a 90 bp cleaved product was also detected, indicating the presence of a mismatch in one allele. Sequence analysis showed substitution of an adenine for guanine in coding position 1817.

CLINICAL CHARACTERISTICS

Seven members of Family 1 had HCM, of whom five are alive. One patient died from sudden cardiac death (SCD) and another from recurrent cerebral emboli. In Family 2, 15 individuals had HCM of whom nine have died, seven from SCD. The mean age at the time of SCD was 33 years. The third family is comprised of 11 affected individuals and one obligate carrier, of whom one patient died at age 17 from progressive heart failure. Two additional individuals in this family have also succumbed to SCD to age 60. A variety of clinical and echocardiographic manifestations of HCM were present in each family. Logrank test of Kaplan-Meier survival curves indicates that Arg403 Gln mutation was associated with a poor prognosis in HCM families as compared to Val606 Met (P = 0.034).

CONCLUSIONS

beta MHC mutations despite showing variable clinical and echocardiographic manifestations of HCM are predictors of survival in HCM families.

Molecular genetics of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is genetically and phenotypically a heterogeneous disease. Genes identified include the beta myosin heavy chain gene (beta MHC) on chromosome 14q1, the troponin T gene on chromosome 1q, and the alpha tropomyosin gene on chromosome 15q. In addition, a fourth locus is present on chromosome 11q11, but the gene remains to be identified. More than 35 missense mutations in the beta MHC, 3 mutations in troponin T, and 2 mutations in alpha tropomyosin gene in HCM patients have been identified. Functional studies have shown that the mutant beta MHC protein has impaired actomyosin interaction and that expression of the mutant myosin disrupts the assembly of sarcomere in feline cardiocytes. Genotype-phenotype correlations of beta MHC mutations have shown that mutations such as Arg403Gln, Arg453Cys, and Arg719Trp are associated with a high incidence of sudden cardiac death and a significantly decreased life expectancy, whereas mutations Gly256Glu and Leu908Val have a near-normal life span. Preclinical genetic diagnosis should help in genetic counseling and therapeutic stratification.