Cerebral arteriovenous malformations in the neonate: clinical presentation, diagnosis and outcome

We reviewed the diagnostic features and clinical outcome of 7 consecutive neonates who were diagnosed to have cerebral arteriovenous malformations. All presented with cardiac failure, and a cranial bruit was heard in 6/7 patients. There was electrocardiographic evidence of myocardial ischemia in 6 patients. The diagnosis was established at cardiac catheterization, or by cardiac and cranial ultrasound. Three patients died of heart failure before definitive treatment. Despite early intervention, three of the remaining four patients died either during or immediately after embolization or ligation of the fistula. A cerebral arteriovenous malformation is a rare cause of neonatal heart failure. Despite prompt recognition and aggressive treatment, the outlook for symptomatic neonates is poor.

Identification of single-stranded-DNA-binding proteins that interact with muscle gene elements

A sequence-specific DNA-binding protein from skeletal-muscle extracts that binds to probes of three muscle gene DNA elements is identified. This protein, referred to as muscle factor 3, forms the predominant nucleoprotein complex with the MCAT gene sequence motif in an electrophoretic mobility shift assay. This protein also binds to the skeletal actin muscle regulatory element, which contains the conserved CArG motif, and to a creatine kinase enhancer probe, which contains the E-box motif, a MyoD-binding site. Muscle factor 3 has a potent sequence-specific, single-stranded-DNA-binding activity. The specificity of this interaction was demonstrated by sequence-specific competition and by mutations that diminished or eliminated detectable complex formation. MyoD, a myogenic determination factor that is distinct from muscle factor 3, also bound to single-stranded-DNA probes in a sequence-specific manner, but other transcription factors did not. Multiple copies of the MCAT motif activated the expression of a heterologous promoter, and a mutation that eliminated expression was correlated with diminished factor binding. Muscle factor 3 and MyoD may be members of a class of DNA-binding proteins that modulate gene expression by their abilities to recognize DNA with unusual secondary structure in addition to specific sequence.

Aortic-ventricular tunnel in a neonate: diagnosis and management based on cross sectional and colour Doppler ultrasonography

A five day old symptom free neonate was referred for assessment of a to and fro murmur associated with large volume pulses. Cross sectional echocardiography and colour flow mapping confirmed the diagnosis of an aortic-ventricular tunnel with forward flow into the aorta and regurgitant flow into the ventricle through both the tunnel and the dilated aortic valve ring. Surgical correction by patch closure of the aortic end of the tunnel was successfully undertaken two weeks later without any additional investigations. Postoperative echocardiography and colour flow imaging showed no aortic regurgitation and normal left ventricular dimensions and function.

Mapping point mutations in the Drosophila rosy locus using denaturing gradient gel blots

Mutations within the rosy locus of Drosophila were mapped using blots of genomic DNA fragments separated on denaturing gradient gels. DNA sequence differences between otherwise identical small rosy DNA fragments were detected among the mutants as mobility shifts on the blots. Mutations were mapped to within a few hundred base pairs of rosy sequence in 100 of 130 mutants tested--a 77% detection rate. The sequence changes in 43 rosy mutations are presented; all but six of these were single base changes. Thirty-four of 36 sequenced mutations induced by the alkylating agents N-ethyl-N-nitrosourea and ethyl methanesulfonate were transitions. All of the mutations mapped in the rosy transcription unit. Twenty-three of the 43 sequenced mutations change the predicted rosy gene polypeptide sequence; the remainder would interrupt protein translation (17), or disrupt mRNA processing (3).

Calculating the frequency of occurrence of a blood type for a 'random man'

A scheme is offered for the calculation of blood group frequencies for mixed racial populations. The issue of which population to model is discussed. Consideration is also given to the racial composition of the desired survey and to the rule of mutual independence. The scheme can in many cases be applied to existing data.

Appendicular skeletal status and hip fracture in the elderly: 14-year prospective data

Fourteen-year follow-up of 535 elderly people included in a British survey in 1973 revealed 23 incident hip fractures. The relationship between appendicular bone mass, assessed in the initial survey by metacarpal morphometry, and fracture risk was analyzed. There was an increased risk of hip fracture with declining metacarpal cortical index at baseline. The risk increase, however, was not statistically significant. It remained similar after adjustment was made for the reported prevalence of falls. These prospective data suggest that osteoporosis may contribute less to the risk of hip fracture in the very elderly than in younger individuals.

A comparison of UV cross-linking and vacuum baking for nucleic acid immobilization and retention

The effectiveness of UV cross-linking and in vacuo baking for the immobilization and retention of DNA to various solid supports was investigated. Optimal immobilization treatments for supported and unsupported nitrocellulose and nylon membranes were: UV cross-linking at 254 nm with an exposure of 120 milliJoules/cm2, or baking in vacuo for two hours at 80 degrees C. UV-immobilized nitrocellulose-based membranes showed no increase in sensitivity when compared to baked membranes. An increase in sensitivity was observed for UV-immobilized nylon membranes as compared with baked nylon membranes in some instances, although this varied within lots of the membranes tested. Repeated strippings and heterologous reprobings resulted in loss of target DNA from UV-immobilized nylon membranes as compared to baked nylon membranes. Loss of target DNA from UV-immobilized nitrocellulose-based membranes due to repeated strippings and reprobings was even more pronounced. In vacuo baking of supported and unsupported nitrocellulose and nylon membranes was more effective for immobilization, and more importantly, for retention of target DNA through many reprobings of the same blot.

Pulse oximetry: a new non-invasive assessment of peripheral arterial occlusive disease

Peripheral skin perfusion reflects the level of vascularity and viability of a limb and may help in planning the site of amputation or bypass surgery in patients with vascular disease. This study used peripheral pulse oximetry in 20 healthy volunteers and in 20 patients with limb ischaemia. Pulse oximetry saturation levels (Psa,O2) were compared with ankle artery Doppler pressures and transcutaneous oxygen measurements (Ptc,O2). Recordings were taken at two standard sites distally and referenced to finger and forearm to calculate an index. A significant correlation was found between Ptc,O2 and Psa,O2 in patients with ischaemia (r = 0.68, P less than 0.01). A further group of 12 patients with acute limb ischaemia was similarly assessed before and after revascularization. After revascularization mean(s.d.) Ptc,O2 increased from 38(13) to 44(1) mmHg (P greater than 0.05) and mean(s.d.) Psa,O2 increased from 86(3) to 90(4) per cent (P less than 0.01). These data suggest that pulse oximetry is a more sensitive index of peripheral perfusion than Ptc,O2 or ankle artery Doppler pressure and that, because of its accuracy and simplicity, it merits further use.

Dietary calcium, physical activity, and risk of hip fracture: a prospective study

OBJECTIVE

To determine whether low dietary calcium intake and physical inactivity are risk factors for hip fracture among subjects aged 65 and over.

DESIGN

Fifteen year follow up study of a large cohort of randomly selected elderly people living in the community, who had taken part in the 1973-4 survey of the Department of Health and Social Security, and for whom dietary and other data were recorded at initial interview and medical assessment.

SETTING

Eight areas in Britain (England (five), Wales (one), and Scotland (two].

SUBJECTS

1688 Subjects living in the community, of whom 1419 subjects (720 men and 699 women) agreed to participate. 1356 Subjects completed a seven day dietary record and 983 (542 men and 441 women) agreed to be assessed by a geriatrician.

RESULTS

Incidence of hip fracture increased with age and was higher in women than men. Comparison with matched controls showed no evidence that the risk of hip fracture was related to calcium intake: the odds ratio for the lowest third of dietary calcium compared with the highest was 0.7 (95% confidence interval 0.1 to 3.9) after adjustment for smoking and body mass index. The adjusted odds ratio for the lowest third of outdoor activity compared with the highest was 4.3 (0.7 to 26.8), and that for grip strength was 3.9 (0.7 to 23.0).

CONCLUSIONS

Reduced intake of dietary calcium does not seem to be a risk factor for hip fracture. Further evidence is provided that physical activity in the elderly protects against hip fracture.

Rapid determination of sequence variations in actinidin isolated from Actinidia chinensis (var. Hayward) using fast atom bombardment mapping mass spectrometry and gas phase microsequencing

A current limitation in the use of fast atom bombardment (FAB) mass spectrometric mapping of peptide mixtures, derived from enzymic digestion of proteins, is that most of the hydrophilic peptides are not observed. However, it has been demonstrated from previous work that esterification of the peptide mixture results in the detection of almost all peptides in FAB mass spectrometry. This strategy of FAB mapping was applied to the protein actinidin, isolated from an Italian variety of Actinidia chinensis. Two of the 12 tryptic peptides in FAB mass spectrometry did not exhibit molecular ions predicted from the known sequence of actinidin isolated from the New Zealand variety of A. chinensis. The two peptides were isolated by high-performance liquid chromatography, subjected to Staphylococcus aureus V8 protease digestion and sequenced by gas-phase microsequencing. Nine changes in amino acid composition were detected using the rapid and powerful combination of FAB mass spectrometric mapping and gas-phase microsequencing.

Cross-binding of factors to functionally different promoter elements in c-fos and skeletal actin genes

A conserved 28-base-pair element in the skeletal actin promoter was sufficient to activate muscle-specific expression when placed upstream of a TATA element. This muscle regulatory element (MRE) is similar in structure to the serum response element (SRE), which is present in the promoters of the c-fos proto-oncogene and the nonmuscle actin genes. The SRE can function as a constitutive promoter element. Though the MRE and SRE differed in their tissue-specific expression properties, both elements bound to the same protein factors in vitro. These proteins are the serum response factor (SRF) and the muscle actin promoter factors 1 and 2 (MAPF1 and MAPF2). The SRF and MAPF proteins were resolved by chromatographic procedures, and they differed in their relative affinities for each element. The factors were further distinguished by their distinct, but overlapping, methylation interference footprint patterns on each element. These data indicate that the differences in tissue-specific expression may be due to a complex interaction of protein factors with these sequences.

Occupational causes of low-back pain

Associations between occupational activities and low-back pain (LBP) were examined in a retrospective postal survey of 545 randomly selected adults. Each subject gave a lifetime occupational history on six specified physical activities and also a lifetime history of LBP. Among the 436 subjects answering the questionnaire, the lifetime incidence of LBP was 63%. The occurrence of LBP was related by Cox's proportional hazards regression model to occupational activities in the year prior to the onset of symptoms. For the men the strongest associations were with heavy lifting and prolonged car driving. There was also an association with heavy lifting among the women. These risks were exaggerated in the subset of subjects whose LBP followed a chronic unremitting course. The findings are consistent with previous reports linking LBP with manual materials handling and driving at work. However, in this sample, less than 20% of the cases could be attributed to such activities.

DNA-binding site for two skeletal actin promoter factors is important for expression in muscle cells

Two nuclear factors bind to the same site in the chicken skeletal actin promoter. Mutations in the footprint sequence which eliminate detectable binding decrease expression in transfected skeletal muscle cells by a factor of 25 to 50 and do not elevate the low expression in nonmuscle cells. These results show that the factor-binding site contributes to the activation of expression in muscle cells and that it alone does not contribute significantly to repress expression in nonmuscle cells.

Influence of polarization state and absorption gratings on photorefractive two-wave mixing in GaAs

The polarization dependence of two-wave mixing for two common crystal orientations is described and theoretical and experimental results given. The direction of energy exchange can be determined by the polarization of the two beams. Absorption gratings are proposed to explain fully the experimental results.

Two nuclear factors compete for the skeletal muscle actin promoter

We show that DNA fragments, which span the skeletal muscle alpha-actin promoter, form specific complexes with proteins from nuclear extracts of 11 different cultured cell types. These include two myocyte stage specific cell types, myoblast and myotube. The myocyte nuclear extracts are distinguished from all of the others by the electrophoretic mobility of the predominant DNA complex. This complex is greatly diminished in the nine non-myocyte cell types, where a different complex predominates. The major myocyte and non-myocyte complexes are caused by distinct binding activities that compete for the same DNA sequence element. DNA footprint analysis shows that this element is located 78 nucleotides upstream of the transcription start site, within a region that appears essential for expression in developing myocytes.

Optimum pacing mode for patients with angina pectoris

A within patient double blind prospective study of symptoms and exercise tolerance was designed to determine the preferred pacing mode in 10 patients with programmable dual chamber pacemakers who also had angina pectoris. Patients were randomly allocated to one month in each of the following modes: ventricular pacing at 70 beats/min (VVI) or atrioventricular synchronous upper rate 150 beats/min (DDD 150) or 100 beats/min (DDD 100). Medications were unchanged throughout the study; none was taking beta blockers. At the end of each month patients underwent an exercise test. During each month patients recorded symptoms and their preferred pacing mode. DDD 100 was the preferred mode (seven patients). There was significantly less chest pain with this mode than with either of the other modes. There were significantly more episodes of dizziness in VVI, and two patients who developed pacemaker syndrome were unable to complete the pacing period. Three patients developed angina during exercise testing in DDD 150. Atrial synchronous ventricular pacing is better than ventricular pacing for the control of symptoms in patients with angina pectoris provided that the upper atrial tracking rate is limited.

Effect of early treatment with nifedipine in suspected acute myocardial infarction

In this single centre prospective, double blind study, 98 patients with suspected acute myocardial infarction (AMI) were randomized, within six hours, to nifedipine 10 mg (46 patients) or placebo (52 patients) both administered sublingually. The delay time from onset of chest pain to treatment was 3.33 +/- 0.2 hours (mean +/- SEM) and 3.28 +/- 0.18 hours for the nifedipine and placebo treated groups, respectively. Treatment was continued orally for 3 days. AMI was confirmed in 28 patients given nifedipine and 23 patients given placebo. Infarct sizing by CK-MB isoenzyme release was possible, for technical reasons, in only 23 patients on nifedipine and 17 patients on placebo. CK-MB isoenzyme release was 710 +/- 104 IU l-1 and 655 +/- 118 IU l-1 for the nifedipine and placebo treated groups respectively (P greater than 0.05). In the acute coronary insufficiency (ACI) group--18 patients given nifedipine and 29 patients given placebo--there was no significant difference in duration of admission, urgent cardiac readmission or progression to AMI within one month. Study withdrawal occurred in 15.3%--8 nifedipine and 7 placebo. Overall, one month mortality was 10.2% with 5 deaths in both the nifedipine and placebo treated groups. Early treatment with nifedipine did not reduce enzymatically determined infarct size or one month mortality in patients with AMI, or reduce one month morbidity or mortality in patients with ACI.

Enzyme Immunoassay for Detection of Salmonella in Foods: Collaborative Study

A collaborative study was performed in 25 laboratories to validate an enzyme immunoassay (EIA) procedure utilizing 2 specific monoclonal antibodies for rapid detection of Salmonella in foods. The EIA was compared with the standard culture procedure for detection of Salmonella in 6 food types: ground black pepper, soy isolate, dried whole eggs, milk chocolate, nonfat dry milk, and raw deboned turkey, Uninoculated and inoculated samples were included in each food group analyzed, with the exception of poultry which was naturally contaminated. There was no significant difference in the productivity of the EIA and culture procedures at the 5% level for any of the 6 foods. The enzyme immunoassay screening method has been adopted official first action.

Calcifying epithelial odontogenic tumours in three cats and a dog

Neoplasms histologically similar to calcifying epithelial odontogenic tumour (CEOT) of man are described in three cats and a dog. The diagnostic features of these neoplasms are their occurrence in the jaw and the histological appearance of cords of epithelial cells, amyloid spherules and foci of calcification. The histogenesis and behaviour of the tumour are discussed.

Branch point control by the phosphorylation state of isocitrate dehydrogenase. A quantitative examination of fluxes during a regulatory transition

To understand how enzymatic pathways respond to changing external conditions, the fluxes through the tricarboxylic acid cycle and ancillary reactions were determined under three different growth conditions in Escherichia coli. The velocities through the major steps in each pathway were measured (a) for growth on acetate alone, (b) for growth on acetate plus glucose, and (c) during the transition caused by addition of glucose to cells growing on acetate. During the transition, the carbon flow through the Krebs cycle decreased by a factor of 5 despite an increase in the growth rate of the culture. Under these conditions, the dephosphorylation of isocitrate dehydrogenase caused a 4-fold increase in its activity. This, together with the decreased rate of substrate production and the kinetic parameters of the branch point enzymes, led to a cessation of the flux through the glyoxylate shunt. The decreased rate of acetyl-CoA turnover, not an inhibition of acetate transport, caused a slower rate of acetate uptake in the presence of glucose. The modulation of protein phosphorylation and metabolite levels is one of the regulatory mechanisms which enables the bacterium to make dramatic shifts between metabolic pathways within a fraction of a doubling time.

Characterization of rate-controlling steps in vivo by use of an adjustable expression vector

Citrate synthase (EC 4.1.3.7) was varied from 10% to 5000% the level found in wild-type Escherichia coli by means of recombinant DNA techniques. When acetate was the sole carbon source, cell growth and carbon flow through the Krebs cycle were greatly affected by the under-production of citrate synthase. In contrast, when glucose was the main nutrient, the same underproduction of citrate synthase had little effect on either growth or carbon flux. When the enzyme was overproduced 50-fold, cultures would grow on glucose but cell division could be abruptly stopped by adding acetate to the medium. These results indicate that the regulatory properties of citrate synthase are highly dependent on the carbon-source composition of the medium. Furthermore, recombinant DNA technology can be used to alter rate-controlling steps in biological pathways and elucidate the regulatory properties of metabolic systems.

The branch point effect. Ultrasensitivity and subsensitivity to metabolic control

The interdependence of the activities of branch point enzymes which compete for a common substrate can yield ultrasensitivity or subsensitivity to control, even if the competing enzymes follow Michaelis-Menten kinetics. The nature of this "branch point effect" for a particular system depends on the kinetic parameters of the competing enzymes, the rate of substrate production leading into the branch point and the type of regulatory mechanism involved. With physiologically reasonable parameter values, the branch point effect can give ultrasensitivity equivalent to an allosteric enzyme with a Hill coefficient of 8 or higher. An experimental example of this ultrasensitivity was provided by the branch point between isocitrate lyase (of the glyoxylate bypass) and isocitrate dehydrogenase in Escherichia coli. The glyoxylate bypass is very active during growth on acetate but its flux decreases by a factor of approximately 150 upon addition of glucose. This inhibition is brought about by two relatively modest events: a 4-fold increase in the maximum velocity of isocitrate dehydrogenase and a factor of 5.5 decrease in the rate of isocitrate production. The mechanism which underlies this sensitivity amplification is discussed.

Incidence of Legionella organisms in selected Ontario (Canada) cities

The distribution of Legionella pneumophila in water inside buildings was examined by means of culture methods. Cooling tower sumps and condenser valves harboured the organism at the highest frequency and in the highest concentrations. The bacterium was also frequently isolated from potable water systems, including hot and cold mixed taps, drinking water fountains and showers. When water quality parameters were examined, only elevated pH, total particulate nitrogen and alkalinity were correlated with the occurrence of L. pneumophila. Survival of the organism in water was increased at slightly basic pH and lower temperatures. The proliferation of the organism in water within buildings is probably due to a number of interrelated environmental factors that influence its survival and growth.

Application of a computerized medical decision-making process to the problem of digoxin intoxication

A computerized medical decision-making system was used to monitor signs and predisposing factors of digoxin intoxication in patients receiving digoxin. This process automatically reviewed the patient's data base nightly for drug interactions, laboratory data and electrocardiographic findings with known association with digoxin intoxication. These decisions were formated into a "digoxin alert report" and sent to line printers in the nursing division to be placed on the individual patients' charts. To assess the effect of these reports on patient management, a randomized double-blind study was undertaken. Patients were assigned to an alert or nonalert group. Alert reports were withheld from charts of patients in the nonalert group. A medical record review was subsequently carried out, wherein the physician's orders were searched to identify actions taken with possible relation to the digoxin alerts. The computer monitored 396 patients over a 3 month period. Of these, 211 (53%) were randomized to the alert group and 185 (47%) to the nonalert group. Seventy-two percent of patients received at least one alert. The most frequently occurring alerts included: hypoxemia, hypokalemia, concurrent use of a beta-adrenergic blocking agent, renal insufficiency and ventricular arrhythmia. Results from the record review demonstrated a 22% increase in physician actions for the alert group. Specifically, patients in the alert group were 2.7 times more likely to have a serum digoxin determination ordered and 2.8 times more likely to have digoxin withheld on the day of a digoxin alert than were patients in the nonalert group.

Determination of flux through the branch point of two metabolic cycles. The tricarboxylic acid cycle and the glyoxylate shunt

The branch point of the tricarboxylic acid and glyoxylate shunt has been characterized in the intact organism by a multidimensional approach. Theory and methodology have been developed to determine velocities for the net flow of carbon through the major steps in acetate metabolism in Escherichia coli. Rates were assigned based on the 13C NMR spectrum of intracellular glutamate, measured rates of substrate incorporation into end products, the constituent composition of E. coli, and a series of conservation equations which described the system at steady state. The in vivo fluxes through the branch point of the tricarboxylic acid and glyoxylate cycles were compared to rates calculated from the kinetic constants of the branch point enzymes and the intracellular concentrations of their substrates.