The effects of different levels of dietary restriction on aging and survival in the Sprague-Dawley rat: implications for chronic studies

A study was undertaken to determine the effects of incremental levels of dietary restriction (DR) in rats. Survival, growth, reproductive, and dietary intake (DI) variables were monitored in a chronic study in which male Sprague Dawley (SD) rats (NCTR colony) were fed their ration ad libitum (AL), or DR. The main objectives were to determine if low levels of DR could be used to increase the survival rate of SD rats in the chronic bioassay, and to identify the survival characteristics of a long-lived SD rat strain (NCTR colony). The average life span of AL rats was 115 months. At 104 weeks on study (110 weeks of age), the survival rate for the AL and 10%, 25%, and 40% DR groups was 63.4, 87.5, 87.5, and 97.5%, respectively. The largest increase in survival (24.1%) occurred between AL and 10% DR, indicating that very low levels of DR have a significant effect on survival. Whole-body, liver, prostate, and epididymis weights and body length were decreased by DR, whereas brain weight, testicular weight, and skull length were not altered by DR. Rats from the NCTR colony were found to be ideal for chronic studies because they are much longer-lived than other SD stocks. Although the 104-week survival rate for these SD, non-obese AL rats exceeds the FDA's "Redbook" survival guideline (> 50%) for chronic bioassays, the use of DR is advocated because it reduces individual variability in body weight.

Urgent coronary bypass surgery for failed percutaneous coronary intervention in the stent era: Is backup still necessary?

BACKGROUND

Current practice guidelines for performance of percutaneous coronary intervention (PCI) in the United States mandate availability of on-site surgical backup. With the decreasing frequency of urgent coronary bypass surgery (UCABG) with newer technologies, it is unclear whether such backup continues to be necessary.

METHODS

A database of 5655 consecutive patients undergoing PCI at a single center between August 1, 1992, and December 31, 1997, was analyzed. Outcomes were determined as well as clinical, lesion, and procedural characteristics of patients during 4 time periods preceding and during use of coronary stenting.

RESULTS

Frequency of UCABG for failed PCI decreased from 2.2% to 0.6% in the most recent time period (P <.01) with no change in incidence of in-hospital death or myocardial infarction. Incidence of stenting progressively increased to 72% in the latest period. Patients requiring UCABG had a higher prevalence of acute coronary syndromes (95%) and type B lesions (79%), but these characteristics were also common in patients who did not undergo UCABG. Although coronary stents were available during the last 3 periods studied, only 30% of UCABG patients had lesions or complications amenable to stenting, and stenting attempts in these patients were all unsuccessful. Despite stenting and use of perfusion balloons and intra-aortic balloon pumps, only 40% of patients having UCABG were stable and pain free on transfer to the operating room.

CONCLUSIONS

Although use of UCABG for a failed PCI is currently very low, there are no satisfactory predictors, patients requiring UCABG are frequently clinically unstable, and availability of stenting does not reliably eliminate the need for UCABG or result in a decrease in mortality. This small group of patients continues to require readily available surgical standby.

Nitric oxide and the control of firefly flashing

Bioluminescent flashing is essential for firefly reproduction, yet the specific molecular mechanisms that control light production are not well understood. We report that light production by fireflies can be stimulated by nitric oxide (NO) gas in the presence of oxygen and that NO scavengers block bioluminescence induced by the neurotransmitter octopamine. NO synthase is robustly expressed in the firefly lantern in cells interposed between nerve endings and the light-producing photocytes. These results suggest that NO synthesis is a key determinant of flash control in fireflies.

Use of a new HemoCue system for measuring haemoglobin at low concentrations

In many photometers and spectrometers used in routine practice Beer's law (relating absorbance to concentration) fails at low concentrations. A refinement of the HemoCue haemoglobin system (HemoCue AB, Sweden) provides a facility for accurate measurement of haemoglobin at the lower end of the scale. This study confirmed excellent linearity of the photometer response of the HemoCue Plasma/Low Hb photometer to haemoglobin concentration by direct measurement on whole blood samples, thus providing a reliable method when laboratory facilities are limited and where critical patient management may be dictated by the severity of anaemia. Furthermore, measurements on plasma and on samples of urine containing haemoglobin demonstrated the utility of the device for reliable quantification of plasma haemoglobin and haemoglobinuria, thus providing a useful method in investigating moderate or severe intravascular haemolysis. A study of plasma haemoglobin on stored samples of ethylenediamine tetraacetic acid (EDTA) blood showed that a small but measurable degree of lysis occurs after two days at room temperature and after four days when stored at 4 degrees C. This effect on the red cell count will reflect on the reliability of using such blood as a quality control preparation.

Leucodepletion and the interaction of polymorphonuclear cells with endothelium in systemic inflammatory response syndrome

The abnormal interaction of polymorphonuclear cells (PMNs) with blood vessel walls is considered to underlie the multiple organ failure of systemic inflammatory response syndrome (SIRS). This consideration is supported by the present finding that PMNs from patients with SIRS are activated, as assessed by an increased distribution of cells bearing CD64, enhanced expression of CD11b and decreased expression of CD62L, and are highly adhesive to endothelial monolayers. Passage of SIRS blood through leucodepletion filters in a laboratory-designed extracorporeal circuit resulted in a marked depletion of PMNs. Of the PMNs that remained in the blood, far fewer cells bound to cultured endothelial cells in comparison with PMNs prior to leucofiltration. We propose that leucofiltration of SIRS blood will limit the number of PMNs available for binding to blood vessel walls and, hence, reduce the pathological manifestations associated with this disorder.

The effect of stimulus-response compatibility on cortical motor activation

Stimulus-response compatibility (SRC) is a general term describing the relationship between a triggering stimulus and its associated motor response. The relationship between stimulus and response can be manipulated at the level of the set of stimulus and response characteristics (set-level) or at the level of the mapping between the individual elements of the stimulus and response sets (element-level). We used functional magnetic resonance imaging (fMRI) to investigate the effects of SRC on functional activation in cortical motor areas. Using behavioral tasks to separately evaluate set- and element-level compatibility, and their interaction, we measured the volume of functional activation in 11 cortical motor areas, in the anterior frontal cortex, and in the superior temporal lobe. Element-level compatibility effects were associated with significant activation in the pre-supplementary motor area (preSMA), the dorsal (PMd) and ventral (PMv) premotor areas, and the parietal areas (inferior, superior, intraparietal sulcus, precuneus). The activation was lateralized to the right hemisphere for most of the areas. Set-level compatibility effects resulted in significant activation in the inferior frontal gyri, anterior cingulate and cingulate motor areas, the PMd, PMv, preSMA, the parietal areas (inferior, superior, intraparietal sulcus, precuneus), and in the superior temporal lobe. Activation in the majority of these areas was lateralized to the left hemisphere. Finally, there was an interaction between set and element-level compatibility in the middle and superior frontal gyri, in an area co-extensive with the dorsolateral prefrontal cortex, suggesting that this area provided the neural substrate for common processing stages, such as working memory and attention, which are engaged when both levels of SRC are manipulated at once.

Psychological distress and substance use by adolescent mothers: associations with parenting attitudes and the quality of mother-child interaction

This study examines associations between psychological distress and alcohol and drug use across the first five years of raising a child and parenting quality at child age six for 185 adolescent mothers. Overall, alcohol and other drug use in this sample was relatively low, but drug use was associated with more mother-reported unrealistic expectations of child behavior and more attributions of child intent to annoy parent by misbehaving. Maternal psychological distress was associated with maternal reports of negative control (yelling, pushing, spanking, etc.), and alcohol use moderated the association between psychological distress and negative control. At low levels of alcohol use, more maternal distress was associated with greater negative control; at higher levels of alcohol use, maternal distress was not related to negative control, but the absolute level of negative control was similar to that reported by more distressed mothers. Neither psychological distress nor alcohol and other drug use were related to maternal behavior during an interaction task. Overall, much stronger associations with parenting outcomes were found for an index of maternal vocabulary, compared with maternal psychological distress or maternal alcohol and other drug use.

Validity of the haemoglobin colour scale in blood donor screening

BACKGROUND AND OBJECTIVES

The haemoglobin colour scale (HCS) has been developed as a simple, reliable and inexpensive clinical device for diagnosing anaemia and estimating its severity when laboratory-based haemoglobinometry is not available. The purpose of this study was to assess its validity for screening blood donors for anaemia.

MATERIAL AND METHODS

The HCS was tested at five blood transfusion centres on a total of 2801 donors. Blood was obtained by skin puncture as part of the routine procedure at the donor sessions. HCS readings were compared with screening by the copper sulphate method, which was in routine use in the centres, and with haemoglobin (Hb) measurements by means of calibrated HemoCue haemoglobinometers. HCS readings were considered as normal when the readings were > or = 12 g/dl.

RESULTS

Analysis of the paired results showed that the HCS had an accuracy of 97.5% in distinguishing subjects with normal Hb from those below the acceptable limit, when checked against the HemoCue. The HCS was more reliable than the copper-sulphate specific-gravity method, yielding 3.7% false readings compared with 6.1% false readings, respectively. When discrimination was set at 12 g/dl with the HemoCue, the HCS gave an incorrect reading in 2.4% of donors. The majority of these false results (44 donors; 1.58%) were caused by the HCS indicating rejection of the donor (i.e. Hb < 12 g/dl) when the correct Hb was higher, whilst in 23 donors (0.82%) the HCS incorrectly indicated a normal Hb; however, in all but four of these donors the correct Hb values were 11.0-11.9 g/dl, and none were below 10 g/dl.

CONCLUSION

The operators were able to master the HCS technique after a few minutes of practice, and all found the test to be user friendly and easy to read. The HCS is proposed as a replacement for the copper sulphate method for blood transfusion donor selection.

Clinical use of WHO haemoglobin colour scale: validation and critique

AIM

The World Health Organisation (WHO) haemoglobin colour scale has been developed as a simple, inexpensive clinical device for diagnosing anaemia when laboratory based haemoglobinometry is not available. In an initial validation study at several health centres, scale readings were compared with measurements of haemoglobin by the laboratory. This showed the scale to have 90% sensitivity and 70% specificity in identifying whether anaemia was present or not. In addition, when present, the degree of anaemia was correctly classified in clinical terms as moderate, pronounced, or severe, with an overall sensitivity of 60% and specificity of 88%. Errors were mainly marginal--that is, between two adjacent categories--but there were also some major discrepancies, such as a blood with a haemoglobin of 6-7 g/dl being read as normal or vice versa. Because this would compromise the scale's reliability in practice, this study was undertaken to identify the cause of the discrepancies and to reassess the performance of the scale.

METHODS

Venous blood samples were collected into potassium EDTA from patients attending selected clinics at three South African hospitals with good laboratory facilities. A prototype of the device was used unsupervised by nursing staff, doctors, and phlebotomists, who were told to follow the printed instructions. The blood specimens were then immediately sent to the laboratory where haemoglobin was measured by standardised automated blood cell counters. Any discrepancies > 1 g/dl were recorded and the tests were repeated by the same operators under supervision of the investigators.

RESULTS

Almost all the errors that occurred resulted from the incorrect use of the device, namely: inadequate or excessive blood, reading the results too soon or too late (beyond the limit of two minutes), poor lighting, or holding the scale at the wrong angle. The accuracy improved dramatically when the tests were repeated under supervision and these faults were avoided: 95% of readings were within 1 g/dl of the reference measurements, and 97% within 1.5 g/dl. Anaemia screening showed 96% sensitivity and 86% specificity. Clinical judgement of pallor was frequently wrong, whereas the scale gave the correct diagnosis in more than 97% of cases.

CONCLUSION

The study confirmed the usefulness and reliability of the scale and its advantage over clinical signs for the diagnosis of anaemia, thus providing a clinically reliable near patient method in the absence of a laboratory. The instructions are easy to follow but must be strictly adhered to.

Measurement of total RBC volume relative to lean body mass for diagnosis of polycythemia

An elevated total RBC volume (TRCV) in milliliters per kilogram of body weight has been an essential criterion for determining whether a person is polycythemic. This may be misleading in obese subjects as the TRCV per kilogram of fat is only one-tenth that of the TRCV of the lean body mass (LBM). Various formulas based on surface area have been used to account for this difference, but they are not always reliable. Direct measurement of TRCV per kilogram of lean body mass was obtained originally in studies in which body composition was determined by the combined body density and total body water measurement method. This is impractical as a routine procedure, but simple-to-use instruments are now available for direct measurement of a person's body composition and percentage of fat by impedance technology. Thus, the TRCV can be obtained by a direct measurement that discounts the effects of fat, and a graph has been designed to normalize the TRCV to milliliters per kilogram of LBM. The TRCV for men and women has been established as 36 mL/kg LBM; when it is more than 43 mL/kg LBM, a diagnosis of polychthemia can be made with confidence.

Evolution of the recombination signal sequences in the Ig heavy-chain variable region locus of mammals

The Ig and T cell receptor (TCR) loci have an exceptionally dynamic evolutionary history, but the mechanisms responsible remain a subject of speculation. Ig and TCR genes are unique in vertebrates in that they are assembled from V, D, and J segments by site-specific recombination in developing lymphocytes. Here we examine the extent to which the V(D)J recombination in germline cells may have been responsible for remodeling Ig and TCR loci in mammals by asking whether gene segments have evolved as a unit, or whether, instead, recombination signal sequences (RSSs) and coding sequences have different phylogenies. Four distinct types of RSS have been defined in the human Ig heavy-chain variable region (Vh) locus, namely H1, H2, H3, and H5, and no other RSS type has been detected in other mammalian species. There is a well-supported discrepancy between the evolutionary history of the RSSs as compared with the Vh coding sequences: the RSS type H2 of one Vh gene segment has clearly become replaced by a RSS type H3 during mammalian evolution, between 115 and 65 million years ago. Two general models might explain the RSS swap: the first involves an unequal crossing over, and the second implicates germline activation of V(D)J recombination. The Vh-H2/RSS-H3 recombination product has likely been selected during the evolution of mammals because it provides better V(D)J recombination efficiency.

Postcleavage sequence specificity in V(D)J recombination

Unintended DNA rearrangements in a differentiating lymphocyte can have severe, oncogenic consequences, but the mechanisms for avoiding pathogenic outcomes in V(D)J recombination are not well understood. The first level at which fidelity is instituted is in discrimination by the recombination proteins between authentic and inauthentic recombination signal sequences. Nevertheless, this discrimination is not absolute and cannot fully eliminate targeting errors. To learn more about the basis of specificity during V(D)J recombination, we have investigated whether it is possible for the recombination machinery to detect an inaccurately targeted sequence subsequent to cleavage. These studies indicate that even postcleavage steps in V(D)J recombination are sequence specific and that noncanonical sequences will not efficiently support the resolution of recombination intermediates in vivo. Accordingly, interventions after a mistargeting event conceivably occur at a late stage in the joining process and the likelihood may well be crucial to enforcing fidelity during antigen receptor gene rearrangement.

Training health workers to assess anaemia with the WHO haemoglobin colour scale

WHO recommends that all pregnant women be screened for anaemia. In rural Africa this is often done by clinical examination which is known to have variable reliability. The recently developed WHO Haemoglobin Colour Scale may be the answer to this problem as it is simple and reliable. This study examines the training procedure recommended by WHO for the Haemoglobin Colour Scale when resources are very limited. We trained 7 laboratory technicians from the Medical Research Council Laboratories Hospital, Fajara, The Gambia and 13 Community Health Nurses (CHNs) from North Bank Division East, a rural area in The Gambia, to use the Colour Scale. The CHNs used the Scale to estimate haemoglobins on all new bookings to the antenatal clinics for a period of one month and recorded how they were managed. At the end of the study period they completed a qualitative questionnaire about the scale. Both groups of trainees were successfully trained although the WHO protocol for training was impossible to follow due to resource limitations. Eight of the 13 trained CHNs used the scale in practice and recorded 307 estimations with a mean haemoglobin of 9.1 g/dl. The results were normally distributed. Six of the 9 patients with Hb readings of < 4 g/dl were managed correctly. In response to the questionnaire the CHNs thought the scale was cheap, easy and quick to use and as good as the haemoglobinometer they had used previously. The main criticism was that it was not robust enough. The development of a low-technology, cheap, simple and reliable method for measuring haemoglobin is a welcome development. However, a simpler training procedure and a standard way of measuring observer performance are necessary.

Differences in potential reproductive rates of male and female seahorses related to courtship roles

Dwarf seahorses, Hippocampus zosterae (Syngnathidae), are distinguished by extreme morphological specialization for paternal care, the formation of monogamous pair bonds and mating repeatedly over the course of a breeding season. To determine the potential reproductive rates of male and female dwarf seahorses, we measured (1) the maximum number of offspring produced per breeding cycle when sexually receptive mates were unlimited, and (2) the relative time each sex was unavailable for mating ('time out'). We paired sexually isolated males and females with sexually receptive partners and observed them from the day of introduction through to copulation, to determine the length of time it takes each sex to prepare to mate. We conducted additional experiments to determine the length of gestation, which when added to the time needed to prepare to mate and copulate gives an estimate of total reproductive cycle duration, T. We estimated potential reproductive rate by dividing the mean number of offspring produced per breeding cycle by the duration of the breeding cycle (T). We estimated reproductive 'time out' by identifying the period of time males and females were physiologically capable of mating ('time in', S) and subtracting time S from time T. When provided with sexually receptive partners, females took 2 days longer than males to complete courtship and copulation, but neither males nor females remated during gestation. Therefore, males could potentially produce 17% more offspring than females over the course of one breeding season. Females had reproductive 'times out' 1.2 times longer than did males, as they were only capable of mating during the 4 h directly preceding copulation. Thus, H. zosterae males have higher potential reproductive rates and shorter reproductive 'times out' compared with H. zosterae females. These results and previous work indicating that seahorses display traditional courtship roles support the prediction that the sex having the higher potential reproductive rate, or equivalently, the shorter 'time out', will compete more intensely for access to the opposite sex. Copyright 2000 The Association for the Study of Animal Behaviour.

Gamma-irradiation directly affects the formation of coding joints in SCID cell lines

SCID mice have a defect in the catalytic subunit of the DNA-dependent protein kinase, causing increased sensitivity to ionizing radiation in all tissues and severely limiting the development of B and T cell lineages. SCID T and B cell precursors are unable to undergo normal V(D)J recombination: coding joint and signal joint products are less frequently formed and often will exhibit abnormal structural features. Paradoxically, irradiation of newborn SCID mice effects a limited rescue of T cell development. It is not known whether irradiation has a direct impact on the process of V(D)J joining, or whether irradiation of the thymus allows the outgrowth of rare recombinants. To investigate this issue, we sought to demonstrate an irradiation effect ex vivo. Here we have been able to reproducibly detect low-frequency coding joint products with V(D)J recombination reporter plasmids introduced into SCID cell lines. Exposure of B and T lineage cells to 100 cGy of gamma irradiation made no significant difference with respect to the number of coding joint and signal joint recombination products. However, in the absence of irradiation, the coding joints produced in SCID cells had high levels of P nucleotide insertion. With irradiation, markedly fewer P insertions were seen. The effect on coding joint structure is evident in a transient assay, in cultured cells, establishing that irradiation has an immediate impact on the process of V(D)J recombination. A specific proposal for how the DNA-dependent protein kinase catalytic subunit influences the opening of hairpin DNA intermediates during coding joint formation in V(D)J recombination is presented.

The effect of dietary fat on malondialdehyde concentrations in Fischer 344 rats

The effects of dietary fat and age on the level of malondialdehyde (MDA), a product of lipid peroxidation, were investigated in cerebellum, kidney, and liver tissues of female Fischer 344 rats. Groups of rats were fed diets containing various levels of corn oil (3, 5, 10, 15, or 20%), starting at 57 days of age, for a duration of 2, 10, or 20 weeks. High fat diets are thought to promote tumor formation, diabetes, and cardiovascular diseases via induction of oxidation stress, and this can begin early in the lifespan. However, it was observed that rats chronically consuming 3 and 5% corn oil diets yielded significantly higher levels of MDA, as analyzed by high-performance liquid chromatography, compared with those fed higher fat diets. After 20 weeks of feeding, the concentration of MDA in each of the three organs studied showed no significant differences among rats consuming diets containing 10, 15, or 20% corn oil. The levels of MDA were highest in the cerebellum, followed by kidney, and lowest in liver. Over the 20-week feeding period, a decrease in MDA level in both cerebellum and liver was observed.

Stenting for in-stent restenosis: A long-term clinical follow-up

We studied the feasibility, safety, and short- and long-term outcomes of treating coronary in-stent restenosis with primary restenting. Thirty-one patients (32 lesions) were treated. Eleven patients had adjunctive rotational atherectomy. Clinical follow-up was obtained in all 31 patients at a mean of 9.1 +/- 5.5 months by direct phone contact with the patients, medical records, and subsequent hospitalization for recurrent symptoms and/or revascularization. There were no cardiac deaths or myocardial infarctions. In native vessels (26 patients), repeat target lesion revascularization was required in eight patients (31%); two other patients (7.7%) had angina and were treated medically. All vein graft lesions had recurrent restenosis. Significant predictors of recurrent clinical events were lesions in vein grafts, multivessel disease, and use of higher poststent deployment inflation pressures. Primary restenting for in-stent restenosis in native vessels is a safe approach with good short-term outcome. Recurrent restenosis remains a problem, as it does with other devices, particularly in vein graft lesions and in patients with multivessel disease. Restenting for in-stent restenosis should probably be used selectively. Cathet. Cardiovasc. Intervent. 48:143-148, 1999.

Functional characterization of B lymphocytes generated in vitro from embryonic stem cells

To study molecular events involved in B lymphocyte development and V(D)J rearrangement, we have established an efficient system for the differentiation of embryonic stem (ES) cells into mature Ig-secreting B lymphocytes. Here, we show that B lineage cells generated in vitro from ES cells are functionally analogous to normal fetal liver-derived or bone marrow-derived B lineage cells at three important developmental stages: first, they respond to Flt-3 ligand during an early lymphopoietic progenitor stage; second, they become targets for Abelson murine leukemia virus (A-MuLV) infection at a pre-B cell stage; third, they secrete Ig upon stimulation with lipopolysaccharide at a mature mitogen-responsive stage. Moreover, the ES cell-derived A-MuLV-transformed pre-B (EAB) cells are phenotypically and functionally indistinguishable from standard A-MuLV-transformed pre-B cells derived from infection of mouse fetal liver or bone marrow. Notably, EAB cells possess functional V(D)J recombinase activity. In particular, the generation of A-MuLV transformants from ES cells will provide an advantageous system to investigate genetic modifications that will help to elucidate molecular mechanisms in V(D)J recombination and in A-MuLV-mediated transformation.

Palindromy is eliminated through a structure-specific recombination process in rodent cells

Higher eukaryotes are proficient at remodeling palindromic DNA. As shown here, a fully palindromic 15.4 kb circular DNA can be introduced into rodent cells with the novel result that the molecule is reproducibly and site-specifically converted to a monomeric circle. The dimer-to-monomer conversion has not been described previously, and in particular is undetectable in Escherichia coli. Comparative DNA sequence analyses of the new junctions found within the monomer circles suggest that the resolution process involves formation of hairpin DNA structures followed by the introduction of single-strand nicks near their termini. By extension, hairpin nicking combined with non-homologous end-joining may be important as a general mechanism for the main-tenance of genomic stability in mammalian cells. It is suggested that the absence of a comparable strategy for coping with palindrome-induced structure in E.coli and other unicellular organisms underlies a fundamental difference in DNA sequence organiz-ation in the genomes of prokaryotes versus higher eukaryotes.

Developmental trajectories of disruptive behavior problems in preschool children of adolescent mothers

Using hierarchical linear modeling (HLM), we analyzed individual developmental trajectories of disruptive behavior problems between ages 3.5 to 6.0 years for 183 children of adolescent mothers. We examined how the level of problem behavior (intercept) and the rate of change over time (slope) are influenced by child's sex, mother's depression/anxiety symptoms, and mother's use of negative control for regulating child behavior. On average, disruptive behavior decreased from age 3.5 to 6.0. Child sex and maternal depression/anxiety related to the level of behavior problems but not to the rate of change. Boys and children of more depressed/anxious mothers exhibited higher levels of disruptive behavior. Maternal negative control was associated with both level of disruptive behavior and rate of change, and negative control mediated the effects of maternal depression/anxiety. Greater negative control corresponded to higher levels of behavior problems and no reduction in their display over time. Child race moderated effects of negative control.

Choice and stimulus-response compatibility affect duration of response selection

In general, for movements to visual targets, response times increase with the number of possible response choices. However, this rule only seems to hold when an incompatibility exists between the stimulus and response, and is absent when stimulus and response are highly compatible (e.g., when reaching toward the location of the stimulus). Stimulus-response (S-R) compatibility can be manipulated either at the level of stimulus and response characteristics, or at the level of the mapping between elements of the stimulus and response sets. The current study was undertaken to determine the extent of the interaction between choice and each of these two levels of S-R compatibility. Subjects used a joystick to move a cursor in response to two, four or eight possible cues, with S-R compatibility manipulated along two dimensions (type of stimulus, and mapping between stimulus and response sets) in separate blocks of trials. Choice effects were absent when S-R relationships were highly compatible, moderate when incompatible in either of the two dimensions, and greatest when incompatible in both dimensions. These results indicate that choice affects response selection at each stage in the decoding of S-R relationships. Similar but smaller effects were seen for trials in which the stimulus was the same as that presented in the immediately preceding trial, suggesting that repeated stimulus-response transformations are faster and more efficient due to the priming effects of previous trials.

Hairpin coding end opening is mediated by RAG1 and RAG2 proteins

Despite the importance of hairpin opening in antigen receptor gene assembly, the molecular machinery that mediates this reaction has not been defined. Here, we show that RAG1 plus RAG2 can open DNA hairpins. Hairpin opening by RAGs is not sequence specific, but in Mg2+, hairpin opening occurs only in the context of a regulated cleavage complex. The chemical mechanism of hairpin opening by RAGs resembles RSS cleavage and 3' end processing by HIV integrase and Mu transposase in that these reactions can proceed through alcoholysis. Mutations in either RAG1 or RAG2 that interfere with RSS cleavage also interfere with hairpin opening, suggesting that RAGs have a single active site that catalyzes several distinct DNA cleavage reactions.

Effects of movement predictability on cortical motor activation

Humans have the ability to make motor responses to unpredictable visual stimuli, and do so as a matter of course on a daily basis. We used functional magnetic resonance imaging (fMRI) to examine the neural substrate of this behavior in six cortical motor areas. We found that five of these areas (premotor, cingulate, supplementary motor area, pre-supplementary motor area, and superior parietal lobule) showed increased activation in association with an unpredictable behavior compared to a predictable one; only the motor cortex remained unchanged. There was also a quantitative relation between the response time and functional activation in the premotor and cingulate cortex. There was less activation across all the motor areas with repetition of the motor tasks. With the exception of the pre-supplementary motor area, all areas were significantly lateralized, with a greater volume of activation in the hemisphere contralateral to the performing hand. In addition, a left hemisphere dominance was found in the activation of motor cortex and supplementary motor areas. Our results suggest that activation in motor areas is differentially and quantitatively related to higher order aspects of motor behavior such as movement predictability.

Guidelines for organisation and management of external quality assessment using proficiency testing. Expert Panel on Cytometry of the International Council for Standardization in Haematology

This document is intended to assist towards the WHO objective that external quality assessment (EQA) schemes be established at national and/or regional levels world-wide. Quality assurance is defined as all steps taken by the director of a laboratory to ensure reliability of laboratory results and to increase accuracy, reproducibility and between-laboratory comparability. This includes the use of internal quality control procedures and participation in external quality assessment. Internal quality control provides the means for evaluation of analytic test results at the time of testing in order to decide whether they are reliable enough to be released to the requesting clinicians. EQA, on the other hand, refers to a system of retrospective and objective comparison of results from different laboratories by means of proficiency testing (PT) organised by an external agency. The main purpose is to establish between-laboratory and between-method (including between-instrument) comparability, and agreement with a reference standard where one exists. Internal quality control and EQA complement each other and must never be considered as alternatives.

A physical map of the Leishmania major Friedlin genome

An extensive physical map of the Leishmania major Friedlin genome has been assembled by the combination of fingerprint analysis of a shuttle vector cosmid library and probe hybridization. The integrated data obtained for 9004 fingerprinted clones and 974 probes have placed 91.2% of the 33.58-Mb genome into contigs representing each of the 36 chromosomes. This first-generation map has already provided a suitable framework for both high-throughput DNA sequencing and functional studies of the L. major parasite.

Angioscopy of culprit coronary lesions in unstable angina pectoris and correlation of clinical presentation with plaque morphology

This study demonstrates that plaque disruption and thrombus are absent in a considerable number of patients with unstable angina and that culprit lesion morphologies as assessed by angioscopy may differ among the various clinical subsets of patients. Although plaque disruption and thrombus undoubtedly play an important role in the pathogenesis of unstable angina, alternative mechanisms may be responsible for ischemia in some patients.

An inexpensive and reliable new haemoglobin colour scale for assessing anaemia

AIM

To describe a new inexpensive method (the WHO Colour Scale) for estimating haemoglobin concentration from a drop of blood by means of a colour scale, and to compare its reliability with a standard laboratory method of measuring haemoglobin, and its clinical usefulness in field trials.

METHODS

The new colour scale method was used to measure haemoglobin concentration in 1213 random venous blood samples from routine work in four laboratories (one each in the UK, South Africa, Thailand, and Switzerland). Limited field trials of the method for assessing clinical usefulness were done in a rural hospital (in South Africa) staffed by nurses, at two blood donor sessions (one each in South Africa and Thailand), and by nonlaboratory personnel in malaria clinics (in Thailand), following training and a short practice session.

RESULTS

In the laboratory based comparability study the presence of anaemia was reliably detected using the new method with 91% sensitivity and 86% specificity. Clinically relevant levels of anaemia (mild to moderate, pronounced, and severe) were graded and serious anaemia (< 8 g/dl) was identified with an efficiency of 89%. The clinical trials showed the ease and reliability with which the colour scale could be used by non-laboratory persons after brief training. The blood donor trials showed it to be at least as reliable as the copper sulphate method with the advantage of being more convenient.

CONCLUSIONS

The preliminary studies have shown that the WHO Colour Scale is a reliable screening method for detecting anaemia, especially for diagnosing serious anaemia. Following a brief training session health workers found it simple to use and, at a cost of about 1/10th that for traditional photometric analysis, it should be of value in "countries in need" for primary health centres, obstetrical management, paediatric clinics, tropical disease control programmes, blood transfusion donor selection, as well as for industrial health checks and epidemiological studies.

Patient survey of a pharmacist-managed anticoagulation clinic

The literature describing pharmacy involvement with anticoagulation services primarily does not include information about patients' perceptions of this involvement. A 22-question survey was developed and administered to 296 patients enrolled in the anticoagulation clinic at the VA Pittsburgh Health Care System. Excluded patients had fewer than four clinic visits or were followed outside of the anticoagulation clinic. The study period was nine weeks and any missed patients were telephoned. The median response to each question was determined. Similar questions were analyzed for acquiescent trends. Results indicate that, overall, patients are comfortable with pharmacists providing warfarin monitoring and dose adjustments.

Field evaluation of a novel haemoglobin measuring device designed for use in a rural setting

OBJECTIVE

To evaluate the use of a robust, cheap method for haemoglobin estimation by non-laboratory-trained personnel in a rural setting.

DESIGN

Comparative study.

SETTING

Tintswalo Hospital, Acornhoek.

PARTICIPANTS

7 nursing sisters, 4 medical students, 2 lay persons.

OUTCOME MEASURES

Haemoglobin estimates obtained with the colour scale were compared with the 'true Hb' values determined by the H x 3 Bayer-Technicon automated blood analyser.

RESULTS

Although individuals varied in their abilities to use the colour scale, its performance was generally very good when measured against automated haemoglobinometry, as determined by bias and regression analysis and also in terms of its capacity to detect anaemia, as measured by sensitivity, specificity and positive and negative predictive values.

CONCLUSIONS

Haemoglobin estimates obtained with the World Health Organisation colour scale are generally reliable, although cognisance should be taken of individual variability. While the utility of the device in monitoring response to therapy remains to be seen, it promises to be a suitable method for mass screening for anaemia.

Synaptic vesicle glutamate uptake in epileptic (EL) mice

The ATP-dependent glutamate uptake system of synaptic vesicles was investigated in epileptic (EL) mice to determine whether glutamate uptake activity correlates with seizure susceptibility or development. Given the focal seizure onset, glutamate uptake activity was measured in four separate brain regions: cerebrum (minus hippocampus), hippocampus, cerebellum, and brain stem. The EL values were compared to those of age-matched controls; DDY and ABP/LeJ (ABP) mice. The glutamate uptake specific activity for EL cerebrum was significantly higher than that for the control mice (approx. 400 days old), but was not elevated prior to seizure onset (46 days old). No difference in glutamate uptake was observed between the strains in the other brain regions. We conclude that increased synaptic vesicle glutamate uptake is brain-region specific (cerebrum) and is associated with the development or maintenance, rather than the initial cause, of seizures in the EL model of epilepsy.

The formation, transfer, and fate of spermatophores in Photinus fireflies (Coleoptera: Lampyridae)

Fireflies in the genus Photinus have been assumed previously to be among the many insect species in which males transfer primarily sperm during mating. In this study, male P. ignitus and P. marginellus were found to produce a complex proteinaceous spermatophore in four paired male accessory glands, a major component of the spermatophore being formed within prominent spiral glands. The spermatophore is transferred to the female within the first 40 min of copulation, and sperm bundles are released into the spermatheca. The remainder of the spermatophore subsequently undergoes digestion within a specialized sac in the female reproductive tract. To examine the function of male spermatophores, male P. marginellus were fed rhodamine B, resulting in the production of intensely fluorescent spermatophores. After mating with rhodamine-dyed males, females incorporated material derived from male spermatophores into their oocytes within 58 h post mating. Nutrient donations from males during mating are expected to play particularly important roles in female oogenesis in insects with nonfeeding adults, such as Photinus spp. The presence of spermatophores in Photinus is related to marked differences among species in their life histories, mating systems, and mating behaviors.

Cryptic signals and the fidelity of V(D)J joining

V(D)J recombination is responsible for the de novo creation of antigen receptor genes in T- and B-cell precursors. To the extent that lymphopoiesis takes place throughout an animal's lifetime, recombination errors present an ongoing problem. One type of aberrant rearrangement ensues when DNA sequences resembling a V(D)J joining signal are targeted by mistake. This study investigates the type of sequence likely to be subject to mistargeting, the level of joining-signal function associated with these sequences, and the number of such cryptic joining signals in the genome.

Nosocomial transmission of Trichophyton tonsurans tinea corporis in a rehabilitation hospital

OBJECTIVE

Investigate the nosocomial transmission of Trichophyton tonsurans tinea corporis.

DESIGN

Descriptive study of a nosocomial epidemic of tinea corporis.

SETTING

A free-standing inpatient rehabilitation facility.

PARTICIPANTS

Patients and healthcare workers present on an inpatient rehabilitation ward at the time of transmission of tinea corporis.

RESULTS

T tonsurans tinea corporis was transmitted from one patient to four healthcare workers despite early diagnosis and treatment. Infection rates for healthcare workers having major, moderate, and minor contact with the index case were 30%, 17%, and 0%, respectively (overall rate, 25%).

CONCLUSIONS

This study identifies rehabilitation inpatients as another population in which nosocomial transmission of T tonsurans tinea corporis can occur. The high attack rate and transmission, despite early diagnosis and treatment, emphasizes the need for isolation precautions.

Angioscopic assessment of coronary lesions underlying thrombus

This study examines the characteristics of coronary lesions in which thrombus is found as assessed by angioscopy before percutaneous transluminal coronary angioplasty in patients with various coronary syndromes. Our findings demonstrate that the plaque underlying intracoronary thrombus is usually yellow and/or disrupted, and support in vitro observations that lipid-rich plaques are highly thrombogenic and that disruption of these plaques is associated with in situ thrombosis.

Frequency, risk factors, and outcome for bacteremia after percutaneous transluminal coronary angioplasty

The objectives of this study were to examine bacteremias after percutaneous transluminal coronary angioplasty (PTCA) with respect to incidence, outcome, and risk factors. Patients undergoing PTCA from January 1990 through April 1994 were studied; during this period a total of 4,217 PTCAs were performed in 3,473 patients. With use of predefined clinical and microbiologic criteria, bacteremias were divided into 3 categories according to the relation to the PTCA procedure: PTCA-related, unrelated, and indeterminate. Ninety-one patients with at least 1 positive blood culture during a 7-week period after PTCA were identified. The bacteremia was classified as unrelated to the PTCA procedure in 32 patients, PTCA-related in 27, and indeterminant in the remaining 32 patients. The attack rate of PTCA-related bacteremia during the 52-month period was 0.64%. The most common organisms causing PTCA-related bacteremia were Staphylococcus aureus (14 patients), coagulase-negative staphylococci (9 patients) and group B streptococci (6 patients). Septic complications, which included femoral artery mycotic aneurysm, septic arthritis, and septic thrombosis, occurred in 10 patients (0.24%). Independent risk factors for PTCA-related bacteremia included duration of procedure (odds ratio [OR] 2.9; p = 0.04), number of catheterizations at the same site (OR 4.0; p = 0.015), difficult vascular access (OR 14.9; p = 0.007), arterial sheath in place > 1 day (OR 6.8; p = 0.025), congestive heart failure (OR 43.3; p = 0.002). Thus, PTCA-related bacteremia is an infrequent complication of PTCA but can be associated with significant morbidity, particularly when the infecting organism is S. aureus. Four of the 5 risk factors for PTCA-related bacteremia appear to correlate directly with increased vascular injury or maintenance of the arterial entry for the procedure.

Potentiation of nephrotoxicity by H2-antagonists in patients receiving cyclosporine

The literature does not support a pharmacodynamic interaction between H2-antagonists and cyclosporine that would result in potentiation of cyclosporine's nephrotoxicity. The increase in serum creatinine associated with cimetidine, in the majority of cases, is due to competition with creatinine for tubular secretion. Ranitidine is unlikely to produce a change in serum creatinine. Additionally, there is no support for a pharmacokinetic interaction. However, cimetidine may influence peak concentrations of cyclosporine. Besides the clinical data reviewed here, two abstracts concur with these findings. Information was unavailable regarding interactions between cyclosporine and either famotidine or nizatidine that potentiate nephrotoxicity in transplant patients. Furthermore, the drug manufacturers state that no evidence is available to support any interaction of their products with cyclosporine. Thus, interpretation of renal function may be confusing with concomitant administration of cimetidine and cyclosporine unless GFR is accurately monitored. On the basis of the information available at this time, ranitidine may be considered the H2-antagonist of choice in a patient treated with cyclosporine.

The impact of an integrated haematology screening system on laboratory practice

The haematology laboratory of the Royal Postgraduate Medical School is required to handle an increasing workload with decreasing financial resources. An investment in technology was made in order to improve efficiency, meet future demands and to meet high technical standards. This required an increase in automation in the Full Blood Count section with staff redeployed into growth areas. The Sysmex HST 330, comprising an SE 9000 full blood count analyser, R 3000 reticulocyte counter, SP 1 film preparation unit, linked by a transport system was chosen as a comprehensive system. To fully exploit the reflex-testing capabilities and maximize the potential of the HST a computerized decision-making algorithm was developed. We have been able to evaluate the impact of a highly automated approach to FBC screening in a busy diagnostic laboratory.

A patent infarct-related artery is associated with reduced long-term mortality after percutaneous transluminal coronary angioplasty for postinfarction ischemia and an ejection fraction <50%

BACKGROUND

Prognosis after myocardial infarction (MI) is influenced by the presence of post-MI ischemia and possibly the patency of the infarct-related artery. The purpose of this study was to compare long-term outcome (reinfarction and death) in patients with open versus closed coronary arteries after percutaneous transluminal coronary angioplasty performed for MI complicated by persistent ischemia.

METHODS AND RESULTS

Between 1981 and 1989, 505 patients underwent percutaneous transluminal coronary angioplasty for post-MI ischemia at the Deaconess Hospital. Long-term incidence (mean follow-up, 34 months) of death, nonfatal reinfarction, repeated coronary angioplasty, and coronary bypass surgery was determined for 479 patients and then compared on the basis of the status of the artery, open versus closed, at the end of angioplasty. The 5-year Kaplan-Meier actuarial mortality rate was 4.9% for 456 patients with open infarct-related arteries and 19.4% for 23 patients with closed infarct-related arteries (P=.0008). Multivariate Cox proportional hazards analyses controlling for age, sex, number of diseased vessels, type and location of MI, and year of coronary angioplasty revealed a hazard ratio for death for closed compared with open arteries of 6.1 (95% CI, 1.8 to 20.0). Among patients with ejection fractions <50%, a closed artery was associated with a higher mortality (p=.0014) compared with patients with open arteries. The status of the artery was not associated with a difference in mortality in patients with ejection fractions > or = 50%.

CONCLUSIONS

As open artery after coronary angioplasty for post-MI ischemia is associated with significantly lower long-term mortality, particularly in patients with ejection fractions <50%.

Routine perioperative dipyridamole 201Tl imaging in diabetic patients undergoing vascular surgery

OBJECTIVE

To assess the utility of dipyridamole thallium testing in symptomatic and asymptomatic patients with diabetes undergoing vascular surgery.

RESEARCH DESIGN AND METHODS

Dipyridamole 201Tl myocardial scintigraphy was performed preoperatively in 93 consecutive patients with diabetes undergoing peripheral vascular procedures. The utility of clinical and thallium variables in predicting cardiovascular complications was assessed.

RESULTS

Two groups of patients were identified: group A (36 patients) without clinical evidence of cardiac disease and group B (57 patients) with clinical evidence of cardiac disease. Dipyridamole thallium scans were abnormal in 21 of 36 (58%) of group A patients compared with 53 of 57 (93%) of group B patients (P < 0.0001). Compared with group B patients with perfusion defects, group A patients with perfusion abnormalities tended to have fewer defects per scan (2.7 +/- 1.5 vs. 3.6 +/- 1.9, P = 0.05). No perioperative cardiac complications occurred in group A patients while perioperative cardiac complications occurred in 9 of 57 (16%, 95% CI 7-28%) group B patients (P = 0.01). For the entire study population, the complication rate was 10%.

CONCLUSIONS

Diabetic individuals without clinical markers for coronary artery disease appear to be at low risk for adverse postoperative cardiac events after vascular surgery. Preoperative myocardial perfusion imaging may add little to cardiovascular risk assessment in this subgroup of patients with diabetes.