Hemoglobins of the tadpole of the bullfrog, Rana catesbeiana. Structure and function of isolated components.

Four major components of the hemoglobin of the bullfrog tadpole, Rana catesbeiana, have been isolated and characterized structurally and functionally. These components fall into two clear functional classes. Components I and II have substantially higher affinities for oxygen than do components III and IV. Components I and II predominate in very young tadpoles and are largely replaced by components III and IV in older tadpoles. The data (Broyles, R.H., and Frieden, E. (1973) Nature New Biol. 241, 207-209) indicate that component I arises in the kidney and components III and IV in the liver. The synchrony of appearance and functional similarity o components I and II suggest that component II probably also arises in the kidney. Thus the development of the tadpole is associated with the successive proliferation of three distinct populations of red cells, first from the kidney, then from the liver, and finally, after metamorphosis, from bone marrow...     

Heterogeneity of Methicillin-Resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> Strains (MRSA) Characterized by Flow Cytometry

We used fluorescent penicillin Bocillin FL for characterization of control methicillin-resistant Staphylococcus aureus (MRSA) strains belonging to one of four heterogenic classes and comparing them with clinical MRSA isolates. Significant differences in percentage of fluorescent cells and reduction of Bocillin FL binding after incubation with methicillin between control strains from classes I and IV were observed, whereas the strains from classes II and III were differed after incubation with methicillin. According to this criteria, 55.8% of the clinical isolates population were similar to the strain of class IV or homogenic resistant, 11.8% was found as I, and 32.3% were categorized as class II or III. However, continuous diversity of measured features was also discussed.     

The clinical significance of class III (suspicious) urine cytology

I. Sternberg, R. Rona, S. Olsfanger, S. Lew and I. Leibovitch The clinical significance of class III (suspicious) urine cytology Background: Urine cytology, combined with cystoscopy, is the mainstay of the diagnosis and surveillance of urothelial carcinoma (UC). While classes I and II urine cytology are considered benign and classes IV and V are considered malignant the clinical significance of class III urine cytology is unclear. We evaluated the positive predictive value of class III urine cytology for concurrent and subsequent UC. Methods: The records of all class III urine cytology cases during a 3‐year period were retrospectively reviewed for the presence of concurrent and subsequent UC, determined by cystoscopy and histological confirmation. Results: Of 111 cases, 54 (48.7%) were associated with concurrent UC and 14 (12.6%) with subsequent UC after an initial evaluation negative for malignancy, with a mean time to diagnosis of 10.8 months. Of 27 cases of class III urine cytology with no prior history of UC, 13 (48.1%) had concomitant UC and none had subsequent UC. Of 84 cases of class III urine cytology with a prior history of UC, 41 (48.8%) had a concomitant diagnosis of UC and 14 (16.7%) developed UC during their follow‐up, leading to a total of 55 (65.5%) cases of UC. Conclusions: Patients with class III urine cytology and a prior history of UC should undergo a full initial evaluation of their urinary tract, and should be followed vigorously if this evaluation is negative for malignancy. Patients without a prior diagnosis of UC and class III urine cytology should also undergo a full initial evaluation, while further larger studies are needed to elucidate the need for further follow‐up in such patients.     

Debate: Do all patients with heart failure require automatic implantable defibrillators for the prevention of sudden death?

Recent clinical trials indicate that approximately two-thirds of patients in New York Heart Association (NYHA) class II and III, who comprise almost 90% of patients with heart failure, die suddenly. Patients in NYHA class IV usually die of progressive heart failure. Implantation of implantable cardioverters defibrillators (ICDs) in this population would represent a huge logistic problem and economic expense. Clinical trials have recently demonstrated that β-blocker therapy with carvedilol, bisoprolol, and toprol XL decrease the sudden death rate by almost 50%, in addition to impacting significantly on death due to worsening heart failure. This medical approach is beneficial to all patients, and should be our major therapy. However, it is reasonable to attempt to identify that subpopulations of heart failure patients who could benefit from an ICD.     

Phylogenetic classification of prokaryotic and eukaryotic Sir2-like proteins

Sirtuins (Sir2-like proteins) are present in prokaryotes and eukaryotes. Here, two new human sirtuins (SIRT6 and SIRT7) are found to be similar to a particular subset of insect, nematode, plant, and protozoan sirtuins. Molecular phylogenetic analysis of 60 sirtuin conserved core domain sequences from a diverse array of organisms (including archaeans, bacteria, yeasts, plants, protozoans, and metazoans) shows that eukaryotic Sir2-like proteins group into four main branches designated here as classes I-IV. Prokaryotic sirtuins include members of classes II and III. A fifth class of sirtuin is present in gram positive bacteria and Thermotoga maritima. Saccharomyces cerevisiae has five class I sirtuins. Caenorhabditis elegans and Drosophila melanogaster have sirtuin genes from classes I, II, and IV. The seven human sirtuin genes include all four classes: SIRT1, SIRT2, and SIRT3 are class I, SIRT4 is class II, SIRT5 is class III, and SIRT6 and SIRT7 are class IV.     

Isolation and characterization of tox mutants of corynebacteriophage beta.

Seventeen nontoxinogenic (tox) mutants of corynebacteriophage beta have been isolated by using a tissue culture screening technique. The mutants fall into four major classes. Two of the classes, I and II, appear to contain missense and nonsense mutants, respectively. However, classes III and IV have not been previously described. Class III mutants produce two proteins (CRMs) seriologically related to diphtheria toxin, but efforts to demonstrate the presence of more than one tox gene have been successful. Class IV mutants are phenotypically CRM-, failing to produce any detectable protein serologically related to diphtheria toxin. Genetic studies indicate that the mutations in class IV strains are not in a gene distinct form the structural gene for toxin, and that the CRM- strains retain at least a portion of that gene. A natural phage isolate, gamma, behaves in a completely parallel fashion to the class IV mutants. The production of tox+ recombinants through recombination of various pairs of tox phage mutants has been demonstrated. The implications of these findings for the natural history of diphtheria are discussed.     

XY sex reversal syndrome in the mare: clinical and behavioral studies,H-Y phenotype

Summary An inherited genetic disorder causes XY embryos of the horse to develop as mares. On the basis of our study of 38 such mares, we have identified four grades or classes of XY sex reversal according to this scheme: class I, nearly normal female, of which some are fertile; class II, female with gonadal dysgenesis, normal mullerian development; calss III, intersex mare with gonadal dysgenesis, abnormal mullerian development, enlarged clitoris; class IV, virilized intersex characterized by high levels of testosterone. In general, class I and calss II mares were typed H-Y antigen-negative whereas class III and class IV mares were typed H-Y antigen-positive.     

Changes in ant communities along an age gradient of cocoa cultivation in the Oumé region,central Côte d'Ivoire

We identified the extent to which ant diversity occurs despite conversion of forests into cocoa plantations by examining the communities across four age classes of plantations (classes I–IV with increasing age from 0–5 to 21–40 years) and in their original forests. An extensive sampling protocol consisting of pitfall trapping, leaf litter sampling, soil sampling and hand sampling was used to characterize ant species richness and composition in three replicates of each age class and in the remaining forest patches. A total of one hundred ant species was found in all habitats combined. While the forest was the richest habitat (73 species), species richness in the different plantation age classes varied as follows (sorted in descending order): class IV (69 species) > class III (57 species) > class I (52 species) > class II (43 species). Age gradient was thus significantly positively correlated with mean species richness and with the relative abundance of some subfamilies. The species composition differed greatly between some plantation age classes and the forest. The two youngest cocoa age classes (I and II) were most dissimilar to the forest. In contrast, forest ants were well represented in the old cocoa age classes (III and IV). Three functional guilds (generalist predators, specialist predators and territorially dominant arboreal species) were in their relative abundance significantly correlated to the age gradient. Overall, cocoa cultivations retaining a floristically diverse and structurally complex forest structure are a suitable management system for the conservation of ant species of the formerly forested habitats.     

Open-heart surgery in elderly patients.

Between March 1975 and March 1980, 50 patients aged 70 to 78 years underwent open-heart surgery at the Montreal Heart Institute. Coronary bypass was performed in 23 patients, valve replacement in 16 and combined coronary and valve surgery in 11. There were four early deaths, all due to cardiac causes. Early postoperative complications occurred in 58% of the patients. There were seven late deaths, five in the valve replacement groups and two in the isolated coronary bypass group. The cumulative survival rate 5 years after surgery was estimated at 76%. While 82% of the survivors were in functional class III or IV before surgery, 90% were in class I or II when last seen, after an average postoperative follow-up of 3 years. Nonfatal late complications occurred in eight of the survivors, one of whom suffered a major hemorrhage due to anticoagulant therapy. Thus, open-heart operations can be offered to the elderly, with a low risk of operative death. The late clinical improvement, with a return to a normal lifestyle, justifies a surgical approach for patients in otherwise good general condition.     

Does the decline in child injury mortality vary by social class? A comparison of class specific mortality in 1981 and 1991.

OBJECTIVE: To examine whether the decline in child injury death rates between 1981 and 1991 varied by social class. DESIGN: Comparison of class specific child injury death rates for 1979, 1980, 1982, and 1983, with those for the four years 1989-92. SETTING: England and Wales. SUBJECTS: Children aged 0-15 years. MAIN OUTCOME MEASURES: Death rates from injury and poisoning. RESULTS: Death rates from injury and poisoning have fallen for children in all social classes. The decline for children in social classes IV and V (21% and 2% respectively), however, is smaller than that for children in social classes I and II (32% and 37%). As a result of the differential decline in injury death rates, socioeconomic mortality differentials have increased. In the four years 1979-80 and 1982-83 the injury death rate for children in social class V was 3.5 times that of children in social class I. For the four years 1989-92 the injury death rate for children in social class V was 5.0 times that of children in social class I. Poisson regression modelling showed that the trend in the decline in death rates across the social classes was unlikely to have arisen by chance alone. CONCLUSIONS: Socioeconomic inequalities in child injury death rates have increased. If these gradients persist, the Health of the Nation''s target is likely to be met for children in the non-manual social classes but not for those in the manual social classes.     

Plasma levels and diagnostic value of catestatin in patients with heart failure

Catestatin (CST) is an endogenous neuropeptide with multiple cardiovascular activities. The study is to investigate circulating CST levels in heart failure (HF) patients and to evaluate the role of CST as a biomarker for HF. Plasma CST concentrations were measured by enzyme-linked immunosorbent assay in 228 HF patients and 172 controls. Plasma CST gradually increased in patients from NYHA class I to class IV. No significant differences in CST were found among NYHA I, NYHA II patients and controls. Plasma CST in NYHA III and IV patients was higher compared to other groups. Plasma CST levels in HF patients after treatment were similar to admission, but still higher than controls. In a subgroup analysis among the patients with NYHA class III or IV, patients with ischemic etiology had significantly higher CST. Plasma CST levels were similar between patients with preserved and reduced ejection fraction. Multivariable analysis showed that NYHA classes, the etiology of HF (ischemic or not) and estimated glomerular filtration rate independently predicted plasma LogCST levels (P < 0.05). The area under ROC for CST and BNP in moderate to severe HF diagnosis was 0.626 and 0.831, respectively, combining CST and BNP did not improve the accuracy.     

Many genomic regions are required for normal embryonic programmed cell death in Caenorhabditis elegans

To identify genes involved in programmed cell death (PCD) in Caenorhabditis elegans, we screened a comprehensive set of chromosomal deficiencies for alterations in the pattern of PCD throughout embryonic development. From a set of 58 deficiencies, which collectively remove approximately 74% of the genome, four distinct classes were identified. In class I (20 deficiencies), no significant deviation from wild type in the temporal pattern of cell corpses was observed, indicating that much of the genome does not contain zygotic genes that perform conspicuous roles in embryonic PCD. The class II deficiencies (16 deficiencies defining at least 11 distinct genomic regions) led to no or fewer-than-normal cell corpses. Some of these cause premature cell division arrest, probably explaining the diminution in cell corpse number; however, others have little effect on cell proliferation, indicating that the reduced cell corpse number is not a direct result of premature embryonic arrest. In class III (18 deficiencies defining at least 16 unique regions), an excess of cell corpses was observed. The developmental stage at which the extra corpses were observed varied among the class III deficiencies, suggesting the existence of genes that perform temporal-specific functions in PCD. The four deficiencies in class IV (defining at least three unique regions), showed unusually large corpses that were, in some cases, attributable to extremely premature arrest in cell division without a concomitant block in PCD. Deficiencies in this last class suggest that the cell death program does not require normal embryonic cell proliferation to be activated and suggest that while some genes required for cell division might also be required for cell death, others are not. Most of the regions identified by these deficiencies do not contain previously identified zygotic cell death genes. There are, therefore, a substantial number of as yet unidentified genes required for normal PCD in C. elegans.     

Structural and Evolutionary Relationships Among Chitinases of Flowering Plants

The analysis of nuclear-encoded chitinase sequences from various angiosperms has allowed the categorization of the chitinases into discrete classes. Nucleotide sequences of their catalytic domains were compared in this study to investigate the evolutionary relationships between chitinase classes. The functionally distinct class III chitinases appear to be more closely related to fungal enzymes involved in morphogenesis than to other plant chitinases. The ordering of other plant chitinases into additional classes mainly relied on the presence of auxiliary domains—namely, a chitin-binding domain and a carboxy-terminal extension—flanking the main catalytic domain. The results of our phylogenetic analyses showed that classes I and IV form discrete and well-supported monophyletic groups derived from a common ancestral sequence that predates the divergence of dicots and monocots. In contrast, other sequences included in classes I* and II, lacking one or both types of auxiliary domains, were nested within class I sequences, indicating that they have a polyphyletic origin. According to phylogenetic analyses and the calculation of evolutionary rates, these chitinases probably arose from different class I lineages by relatively recent deletion events. The occurrence of such evolutionary trends in cultivated plants and their potential involvement in host–pathogen interactions are discussed. Received: 5 July 1996 / Accepted: 9 January 1997     

Invasive treatment of patients with cardiomyopathy: CRT-ICD better than ICD alone

In the December issue of our journal, special attention is paid to the underlying mechanisms and various manifestations of cardiomyopathy. In particular, new pathways in the diagnosis and treatment of patients with cardiomyopathy have been addressed. Of the modern management strategies, cardiac resynchronisation therapy (CRT) has become a mainstay in the treatment of patients both with ischaemic and nonischaemic cardiomyopathies. CRT induces progressive reverse left ventricular (LV) remodelling and delays disease progression in patients with NYHA class III or IV heart failure. The question whether CRT is also beneficial in patients with NYHA class I and II was recently addressed in the MADIT-CRT trial (Multicenter Automatic Defibrillator Implantation Trial – Cardiac Resynchronization Therapy).     

Differential utilization of beta-tubulin isotypes in differentiating neurites

beta-Tubulin is encoded in vertebrate genomes by a family of six to seven functional genes that produce six different polypeptide isotypes. We now document that although rat PC-12 cells express five of these isotypes, only two (classes II and III) accumulate significantly as a consequence of nerve growth factor-stimulated neurite outgrowth. In contrast to previous efforts that have failed to detect in vivo distinctions among different beta-tubulin isotypes, we demonstrate using immunoblotting with isotype-specific antibodies that three beta-tubulin polypeptides (classes I, II, and IV) are used preferentially for assembly of neurite microtubules (with approximately 70% of types I and II assembled but only approximately 50% of type III in polymer). Immunofluorescence localization shows that an additional isotype (V) is partially excluded from neurites. Distinctions in in vivo localization of the neuron-specific, class III isotype have also been directly observed using immunofluorescence and immunogold electron microscopy. The sum of these efforts documents that some in vivo functional differences between tubulin isotypes do exist.     

Childhood eczema: disease of the advantaged?

OBJECTIVE--To determine whether the increased prevalence of childhood eczema in advantaged socioeconomic groups is due to increased parental reporting. DESIGN--Comparison of parental reports of eczema with visible eczema recorded by medical officers during a detailed physical examination. SETTING--National birth cohort study. SUBJECTS--8279 children from England, Wales, and Scotland born during 3-9 March 1958 and followed up at the ages of 7, 11, and 16. MAIN OUTCOME MEASURES--Prevalence of eczema according to parental report compared with medical officer''s examination at the ages of 7, 11, and 16. RESULTS--Prevalence of both reported and examined eczema increased with rising social class at the ages of 7, 11, and 16 years. The point prevalence of examined eczema at age 7 was 4.8%, 3.6%, 3.6%, 2.4%, 2.2%, and 2.4% in social classes I, II, III non-manual, III manual, IV, and V respectively (chi 2 value for linear trend 12.6, P < 0.001). This trend persisted after adjustment for potential confounders such as region and family size and was not present for examined psoriasis or acne. CONCLUSIONS--Eczema is more prevalent among British schoolchildren in social classes I and II than those in lower classes. Exposures associated with social class are probably at least as important as genetic factors in the expression of childhood eczema.     

Screening errors in cervical cytologic screening

A total of 555 cervical smears, originally classified as Papanicolaou classes I and II, from women in whom three years later cytologic findings consistent with moderate dysplasia, severe dysplasia, carcinoma in situ and invasive cancer were diagnosed were reviewed in order to estimate the screening error. The initial diagnosis proved to be underestimated in 17.5% of the smears. The two diagnoses correlated in 70.2% of the smears while 12.3% of the smears that contained no abnormality were judged to be inadequate for making a diagnosis, probably representing sampling errors. Quality-control measures to reduce these errors are briefly summarized.     

New classification system for oxygenase components involved in ring-hydroxylating oxygenations

Batie et al. [Chemistry and Biochemistry of Flavoenzymes, 3, 543-556 (1991)] proposed a classification system for ring-hydroxylating oxygenases in which the oxygenases are grouped into three classes in terms of the number of constituent components and the nature of the redox centers. But in recent years, many ring-hydroxylating oxygenases have been newly identified and characterized, and found difficult to classify into these three classes. Typical examples are carbazole 1,9a-dioxygenase and 2-oxo-1,2-dihydroquinoline 8-monooxygenase, which have been classified into class III and class IB, respectively, from biochemical characteristics. However, a phylogenetic study showed that the terminal oxygenases of both are closely related to class IA. Because this discrepancy derived from counting all the components together, here we proposed a new scheme based on the homology of the amino acid sequences of the alpha subunits of the terminal oxygenase components. This new scheme strongly reflects the actual phylogenetic affiliation of the terminal oxygenase component. By comparing their sequences pairwise using the CLUSTAL W program, 54 oxygenase components were classified into 4 groups (groups I, II, III, and IV). While group I contains broad-range oxygenases sharing low homology, groups II, III, and IV contain some typical oxygenases: benzoate/toluate dioxygenases for group II, naphthalene/polycyclic aromatic hydrocarbon dioxygenases for group III, and benzene/toluene/biphenyl dioxygenases for group IV. Our new scheme is simple and powerful, since an oxygenase component can be nearly automatically grouped when the DNA sequence is available, and it fits very well with the phylogenetic affiliation.     

Broad sensitivity of rodent arrhythmia models to class I, II, III, and IV antiarrhythmic agents

To determine specificity of rodent models of arrhythmia for different Vaughan Williams classes of antiarrhythmic drugs, we tested 17 drugs from the four classes in one in vitro and four in vivo models. In the mouse chloroform-induced ventricular fibrillation model and in the guinea pig ouabain-induced arrhythmia model, drugs of classes I (amefalone, aprindine, lidocaine, mexiletine, phenytoin, procainamide, or quinidine), II (metoprolol or propranolol), and IV (bepridil) were active. Class III drugs (bretylium, clofilium, or melperone did not suppress ouabain arrhythmias, but were active in the mouse chloroform model. In the rat coronary artery ligation model, disopyramide (class I), amefalone and melperone significantly (P less than 0.05) reduced the number of extrasystoles. Propranolol, sotalol, and verapamil (class IV) were less effective. In the rat coronary artery ligation/reperfusion model, all four classes of antiarrhythmic agents were active in vitro (isolated heart) and in vivo (anesthetized rat). Thus, one model of automaticity, the guinea pig ouabain model, detected class I, II, and IV drugs, whereas another automaticity model, the mouse chloroform model, also detected class III agents. The model of reentry induced by ischemia plus reperfusion (rat coronary artery ligation reperfusion) can be recommended as a screen for new antiarrhythmic agents based on its sensitivity to all four classes of antiarrhythmic drugs. The Vaughan Williams class of an antiarrhythmic agent must be determined, however, by additional mechanism studies.