Properties of adenosine monophosphate deaminase of Candida albicans

Adenosine monophosphate deaminase (AMPD; EC 3.5.4.6) catalyses the hydrolysis of adenosine monophosphate (AMP) to commensurate amounts of inosine monophosphate (IMP) and ammonia. The production of AMP deaminase in Candida albicans was measured in Lee's medium grown cultures. The highest AMPD activity was observed at 24 h of growth. The enzyme had an optimum pH and temperature at 6-7 and 28 degrees C, respectively. This enzyme was inhibited under iron-limited growth conditions as well as by protease inhibitors. The AMPD of C. albicans showed a moderate increase in activity when cultures were grown in the presence of the divalent cations Mg2+, Ca2+, and Zn2+. Moreover, ADP, ATP, adenine, adenosine, deoxyribose and hypoxanthine increased the enzyme activity. Cultures grown in trypticase soy broth exhibited maximum AMPD activity compared with those grown in Sabouraud dextrose broth or Lee's medium.

Elevation of atrial natriuretic peptide prohormone. Hemodynamic background of the elevation of N-terminal natriuretic peptide prohormone in children with congenital heart disease

We postulated previously that variables related to pulmonary flow are independent predictors of levels of atrial natriuretic peptide in children with congenital heart disease. The aim of this study was to test this hypothesis in relation to other hemodynamic and clinical variables. During catheterization we measured the levels of plasma N-terminal atrial natriuretic peptide prohormone in the plasma of 68 children with congenital heart disease. All had undergone complete clinical, echocardiographic and invasive hemodynamic investigations. The influence on the prohormone was analyzed for 10 different variables in a multiple linear regression model. The variability could be explained in large parts (adjusted R2 =77.2%) by variations in atrial pressures or sizes, together with the degree of excessive pulmonary blood flow and signs of heart failure. A value for atrial natriuretic peptide prohormone above 800 pmol/l predicted hemodynamic imbalance (defined as elevated pressures in left or right atrium or the pulmonary arteries, and/or Qp/Qs > 1.5) with a specificity of 94%, a sensitivity of 73%, a positive likelihood ratio of 12.2, and a negative likelihood ratio of 0.29. In conclusion, variables related to pulmonary blood flow are influential determinants of the levels of atrial natriureic peptide in children with congenital heart disease. Atrial pressures, and symptoms of heart failure are also of major importance.

Improving infection control in general practice

Infection control measures in the health care setting should protect patients and staff from cross-infection. The prevention of harm is an essential part of good medical practice and failure might result in professional misconduct proceedings by the General Medical Council (GMC) and prosecution under the Health and Safety at Work legislation, as well as civil liability. For a health authority, overall responsibility for public health includes arrangements for the control of communicable diseases and infection in hospital and the community (NHS Management Executive, 1993), a function usually led by the Consultant in Communicable Disease Control (CCDC). This paper describes one district's collaborative approach between public health and GPs to assess and improve local infection control standards.

Processing of HIV-1 envelope glycoprotein for class I-restricted recognition: dependence on TAP1/2 and mechanisms for cytosolic localization

Processing of viral proteins for recognition by CTL involves degradation of the proteins in the cytosol of an infected cell followed by transport of the resulting peptides into the endoplasmic reticulum (ER) by the TAP1/2 complex. Uncertainty exists over the site of processing of viral envelope (env) proteins since the extracellular domains of env proteins are not present in the cytosol where the class I Ag-processing pathway begins. Rather, the ectodomains of env proteins are cotranslationally translocated into the ER during biosynthesis. To analyze env protein processing, we used the herpes simplex virus protein ICP47 to block peptide transport by TAP1/2 and examined the effects of TAP blockade on the processing of the HIV-1 env protein. For the majority of env-specific CD8+ CTL, the processing pathway required TAP1/2-mediated transport of cytosolic peptides into the ER. To determine how env peptides are generated in the cytosol, we analyzed the processing of two TAP1/2-dependent epitopes containing N-linked glycosylation sites. In each case, processing involved glycosylation-dependent posttranslational modification of asparagine residues to aspartic acid. These results are consistent with cotranslational translocation of env into the ER, where glycosylation occurs. This is followed by export of a fraction of the newly synthesized protein into the cytosol, where it is deglycosylated, with conversion of the asparagines to aspartic acid residues. Following cytoplasmic proteolysis, env peptides are retransported by TAP1/2 into the ER, where association with class I occurs. Thus, the env protein can enter the class I pathway through multiple distinct processing mechanisms.

N-terminal proatrial natriuretic peptide in angina pectoris: impact of revascularization by angioplasty

AIMS

We investigated whether levels of N-terminal proatrial natriuretic peptide (N-terminal proANP) reflect the severity of coronary artery disease in chronic, stable angina pectoris. Furthermore, we investigated if revascularization by percutaneous transluminal coronary angioplasty (PTCA) affected the N-terminal proANP level and, finally, whether restenosis could be predicted by changes in N-terminal proANP after PTCA.

METHODS AND RESULTS

N-terminal proANP was measured in 286 patients before and after PTCA. The patients' baseline level of N-terminal proANP (787+/-403 pmol/l) correlated significantly with left ventricular end diastolic pressure, age and serum creatinine, but not with the number of stenotic vessels. Twenty-four hours post-PTCA N-terminal proANP decreased significantly, and completely revascularized patients demonstrated a decline two-fold larger than those incompletely revascularized (deltaN-terminal proANP -114+/-178 vs. -53+/-231 pmol/l, P<0.05). After 14 days N-terminal proANP had returned to baseline in both groups. Changes in N-terminal proANP from post-PTCA to the final follow-up was not predictive of angiographic restenosis.

INTERPRETATION

The significant decrease in N-terminal proANP observed after angioplasty, most pronounced in patients completely revascularized, is thought to reflect a transient improvement in resting left ventricular function.

Neuropsychological functioning after treatment for hematological malignancies in childhood, including autologous bone marrow transplantation

Neuropsychological functioning and academic achievement were assessed in 26 patients 2-10 years after autologous bone marrow transplantation (ABMT) for childhood hematological malignancies. Serial tests of general intelligence before and after ABMT were supplemented with a cross-sectional study of neuropsychological functioning. Test results for general intelligence were in the normal range and mainly unaffected over time, but below average performance in specific neuropsychological tests was found in a higher number of children than expected, especially for the variables "Strategies," "Attention," and "Memory." All school children were in regular classes; 5/15 obtained extra tutorial help and two of them had major learning difficulties. Eight young adults reported normal academic achievement. Low age at diagnosis and long time since ABMT correlated significantly with lower test results on general intelligence and "Attention," and high intensity of treatment directed to the central nervous system correlated with more learning difficulties as assessed by teachers. Children with identified problems in school were offered educational counseling based on their test profiles. To enable such counseling, it is suggested that both IQ tests and neuropsychological tests on memory and attention be included in follow-up programs for children who have received high-intensity cancer treatment.

Rapid hyaluronan uptake is associated with enhanced motility: implications for an intracellular mode of action

Texas red-labeled hyaluronan (TR-HA) is rapidly taken up in a CD44 independent manner into ras-transformed 10T1/2 fibroblasts, where it accumulates in both cell ruffles/lamellae, the perinuclear area, and the nucleus. HA does not accumulate in the cell ruffles/lamellae of parental 10T1/2 cells. Addition of HA to ras-transformed cells promotes their random motility but has no effect on 10T1/2 cell motility. 10T1/2 cells can be modified to take up HA into cell ruffles by exposure to phorbol ester or direct microinjection of HA into cells. Both treatments significantly stimulate 10T1/2 cell motility.

An experimental study of cardiac natriuretic peptides as markers of development of congestive heart failure

The use of cardiac peptide measurements as possible diagnostic tools in congestive heart failure has been extensively discussed in the recent literature. Therefore, the aim of this study was to establish a model of experimental chronic heart failure, and thereby perform a comparative study of secretion and circulating levels of the cardiac peptides atrial natriuretic peptide (ANP), N-terminal proatrial natriuretic peptide (N-terminal proANP) and brain natriuretic peptide (BNP) during evolving heart failure. Chronic heart failure was induced in seven pigs by rapid left atrial pacing for three weeks. The effects of failure induction were documented 24 h after pacemaker deactivation. Hemodynamic indices of cardiac preload, like pulmonary capillary wedge pressure (PCWP) and right atrial pressure (RAP), were all considerably increased compared to sham operated controls. Likewise, plasma endothelin-L, noradrenaline, renin activity, aldosterone and angiotensin II were all markedly increased. Heart failure was accompanied by significant increases in both estimated cardiac secretory rate and plasma concentrations of all three cardiac peptides, significantly correlated to the PCWP. The directional changes during evolving heart failure were similar, although the percentage increase in plasma BNP was much larger than for ANP and N-terminal proANP. In absolute molar terms, however, the BNP concentration changes were minor compared to those of the other two peptides. The larger percentage increase of BNP might indicate its superiority as a marker of heart failure development, provided a functional assay suitable for clinical use can be designed for a peptide circulating in this low concentration range.

Screening for colorectal cancer: present, past and future

Colorectal cancer results in 18,000 deaths annually in England and Wales, with 24,000 new cases diagnosed each year. Despite a better understanding of the genetics, and advancement in surgical and anaesthetic techniques, there has been little reduction in mortality and morbidity from this disease over the past 25 years. Colorectal cancer fits recognized criteria for a disease that should be screened in asymptomatic individuals. The putative duration of the adenoma to carcinoma sequence gives an ample window of opportunity to detect and treat colorectal cancer. In this article we have reviewed the strategies involved in screening for colorectal cancer in an asymptomatic population. We have presented trials and arguments for and against the different screening methods and discussed cost effectiveness of screening. In the USA and Canada, major professional organizations and societies now endorse screening; in the UK it is still far from being accepted. We feel that the available evidence shows that colorectal cancer screening has the potential to reduce the morbidity and mortality from this disease and that funding for a mass screening and public education programme should be sought.

Deletions in HOXD13 segregate with an identical, novel foot malformation in two unrelated families

Synpolydactyly (SPD) is a dominantly inherited congenital limb malformation consisting of 3/4 syndactyly in the hands and 4/5 syndactyly in the feet, with digit duplication in the syndactylous web. The condition recently has been found to result from different-sized expansions of an amino-terminal polyalanine tract in HOXD13. We report a novel type of mutation in HOXD13, associated in some cases with features of classic SPD and in all cases with a novel foot phenotype. In two unrelated families, each with a different intragenic deletion in HOXD13, all mutation carriers have a rudimentary extra digit between the first and second metatarsals and often between the fourth and fifth metatarsals as well. This phenotype has not been reported in any mice with genetic modifications of the HoxD gene cluster. The two different deletions affect the first exon and the homeobox, respectively, in each case producing frameshifts followed by a long stretch of novel sequence and a premature stop codon. Although the affected genes may encode proteins that exert a dominant negative or novel effect, they are most likely to act as null alleles. Either possibility has interesting implications for the role of HOXD13 in human autopod development.

HIV-infected subjects with the E4 allele for APOE have excess dementia and peripheral neuropathy

HIV produces a chronic viral infection of the central nervous system that elicits chronic glial activation and overexpression of glial cytokines that are also implicated in Alzheimer disease (AD) pathogenesis. A genetic risk factor for AD is the E4 isoform for apolipoprotein E (APOE). Here we compare the frequency of neurologic symptoms for subjects with and without the E4 isoform (E4(+)and E4(-), respectively) in an HIV cohort. Compared with E4(-) subjects, twice as many E4(+) subjects were demented (30% compared with 15%) or had peripheral neuropathy (70% compared with 39%) at least once, and they had threefold more symptomatic examinations (13% compared with 3% and 42% compared with 14%, respectively)(P < 0.0001). Thus, neurologic symptoms for HIV-infection and AD are linked through an etiologic risk factor. Long-term survivors of HIV infection with E4 may be at high risk for AD; conversely, gene-viral interactions may speed AD pathogenesis.

Telemedicine conference on a 13-year-old Chinese girl with an unusual skeletal condition

Departments of Paediatrics, Diagnostic Radiology, Orthopaedics and Traumatology and Chemical Pathology, Prince of Wales Hospital, Shatin, Hong Kong, China; Department of Paediatric Radiology, Hospital for Sick Children, Great Ormond Street Hospital, London, UK

Adverse neonatal effects of maternal labetalol treatment

Two infants with features of severe beta adrenergic blockade, pericardial effusions, and myocardial hypertrophy were born to mothers receiving long term treatment with oral labetalol for hypertension in pregnancy. Labetalol was implicated in the aetiology of these problems. Pericardial effusion and myocardial hypertrophy have not been associated with labetalol toxicity in neonates.

Alterations in classical cadherins associated with progression in ulcerative and Crohn's colitis

Human colitis is a condition associated with a spectrum of altered morphologic changes and cellular adhesion. The role of cadherins, which are powerful morphoregulatory cell adhesion molecules, in colitis is provocative and as yet unknown. Herein, we present results that suggest a strong correlation between the deregulation of two cadherin molecules, E- and P-cadherins, and the progression of human colitis. We examined the expression and structural integrity of E- and P-cadherins in inflamed, dysplastic, or neoplastic human ulcerative colitis (UC) (n=58), human Crohn's colitis (n = 30), and normal tissue (n = 20) to assess cadherin function in normal and abnormal epithelium. E-cadherin is strongly expressed in normal colorectal epithelium, whereas in left-sided UC it is either down-regulated or has a single-base pair mutation in exon 4 resulting in an amino acid alteration (6 of 58 UC cases). By contrast, P-cadherin is dramatically up-regulated in both Crohn's disease and ulcerative colitis and especially in dysplastic ulcerative tissue. In vitro transfected SW-480 colorectal cells containing E-cadherin mutations identical to those in vivo were associated with increased spontaneous disaggregation compared with cells transfected with wild-type E-cadherin. Based on this evidence, we hypothesize that a small subset of colorectal cells expressing mutant E-cadherin are associated with widespread ulceration, whereas those expressing P-cadherin are associated with a rapidly dividing immature phenotype that includes dysplasia. The differential expression of mutated and wild-type cadherins examined herein are associated with a broad spectrum of abnormal epithelial phenotypes, lymphocyte integrin binding, and resistance to denudation, as is seen in the colitis adenocarcinoma sequence.

PAK promotes morphological changes by acting upstream of Rac

The serine/threonine kinase p21-activated kinase (PAK) has been implicated as a downstream effector of the small GTPases Rac and Cdc42. While these GTPases evidently induce a variety of morphological changes, the role(s) of PAK remains elusive. Here we report that overexpression of betaPAK in PC12 cells induces a Rac phenotype, including cell spreading/membrane ruffling, and increased lamellipodia formation at growth cones and shafts of nerve growth factor-induced neurites. These effects are still observed in cells expressing kinase-negative or Rac/Cdc42 binding-deficient PAK mutants, indicating that kinase- and p21-binding domains are not involved. Furthermore, lamellipodia formation in all cell lines, including those expressing Rac binding-deficient PAK, is inhibited significantly by dominant-negative RacN17. Equal inhibition is achieved by blocking PAK interaction with the guanine nucleotide exchange factor PIX using a specific N-terminal PAK fragment. We conclude that PAK, via its N-terminal non-catalytic domain, acts upstream of Rac mediating lamellipodia formation through interaction with PIX.

Power of plasma N-terminal proatrial natriuretic factor to determine haemodynamics in patients with cardiac disease: relation to serum creatinine

OBJECTIVE

The aim was to examine the usefulness of plasma N-terminal proatrial natriuretic factor (N-terminal proANP) as a non-invasive marker of cardiac pressure in patients with normal to mildly elevated serum creatinine.

METHODS

Blood samples were drawn at rest from 100 patients with cardiac disease undergoing diagnostic cardiac catheterization.

RESULTS

Using multivariate analysis, N-terminal proANP was independently related to mean pulmonary capillary wedge pressure (PCWP), mean right atrial pressure, serum creatinine (s-creatinine) and cardiac index. These indices accounted for about 50% of the variation in N-terminal proANP. All patients with N-terminal proANP < 1000 pmol/l had normal PCWP (< 13 mmHg). Areas under the receiver-operating characteristic (ROC) curves for N-terminal proANP for the detection of PCWP > or = 13, > or = 18 and > or = 24 mmHg were 0.903, 0.870 and 0.876, respectively.

CONCLUSION

These results suggest that analysis of plasma N-terminal proANP is a simple and powerful method for assessing cardiac pressure in patients with heart disease and normal and mildly elevated s-creatinine (< 165 micromol/l). The value of N-terminal proANP cannot, however, indiscriminately be used to assess cardiac haemodynamics. N-terminal proANP measurement is a useful screening parameter for identifying patients with normal cardiac pressures.

Calphostin C induces selective disassembly of the Golgi complex by a protein kinase C-independent mechanism

Intact cells incubated with calphostin C, an inhibitor of the regulatory domain of protein kinase C, showed fragmentation and dispersal of the Golgi complex by a light-dependent mechanism. At the ultrastructural level Golgi stacks were replaced by clusters of vesicles and short tubules that resembled the Golgi remnants present in control mitotic cells. Vesicle-mediated transport processes along both the exocytic and endocytic routes were also inhibited by calphostin C treatment. Golgi disassembly, however, was not due to protein kinase C inhibition since several inhibitors of the catalytic domain did not cause a similar effect. In contrast, pretreatment with phorbol 12-myristate 13-acetate partly protected the Golgi complex from disassembly by calphostin C. The in vitro effect was shown to be reversible, required both cytosol and ATP and it was inhibited by pretreatment of the Golgi membranes with trypsin but not with high salt. These results suggest the interaction of calphostin C with a structural Golgi protein containing a phorbol ester-binding domain and necessary for the stability of this organelle during interphase.

A histopathological assessment of the response of rectal adenocarcinoma to combination chemo-radiotherapy: relationship to apoptotic activity, p53 and bcl-2 expression

AIMS

To investigate the use of pre-operative chemo-irradiation in downstaging advanced rectal cancer prior to surgical resection.

METHODS

We examined the pathological effects of chemo-irradiation on 24 rectal tumours and correlated the efficacy of treatment with the level of apoptosis, mitosis, P53 and bcl-2 protein expression on pre-treatment biopsies.

RESULTS

All tumours were resectable following chemo-irradiation. Six cancers showed complete regression with no viable tumour in the resection specimen. A significant correlation was found between spontaneous tumour apoptosis and tumour regression.

CONCLUSIONS

Our results suggest that in rectal cancer the apoptotic rate in untreated tumour tissue may predict sensitivity to radiation and cytotoxic agents. No relationship was found between regression and mitotic rate, p53 or bcl-2 expression.

N-terminal proANF in acute atrial fibrillation: a biochemical marker of atrial pressures but not a predictor for conversion to sinus rhythm. Digitalis in Acute Atrial Fibrillation (DAAF) Trial group

BACKGROUND

Atrial filling pressures are increased in acute atrial fibrillation, which stimulates the release of atrial natriuretic factor pro-hormone, proANF.

METHODS

In a randomized trial comparing digoxin with placebo in 216 patients, we investigated whether the baseline plasma level of N-terminal proANF is a predictor for conversion to sinus rhythm and the relation among N-terminal proANF, conversion to sinus rhythm, and changes in heart rate.

RESULTS

N-terminal proANF was increased at baseline and decreased significantly in patients converting to sinus rhythm, whereas it was mainly unchanged in nonconverters. N-terminal proANF was not a predictor of conversion to sinus rhythm. A relation was found between relative changes in heart rate and N-terminal proANF in nonconverters.

CONCLUSION

The level of N-terminal proANF does not predict conversion to sinus rhythm, which indicates that hemodynamics per se is not important. There is a correlation between relative changes in heart rate and N-terminal proANF in nonconverters.

Temporal dynamics of verbal object comprehension

Knowledge of the stage composition and the temporal dynamics of human cognitive operations is critical for building theories of higher mental activity. This information has been difficult to acquire, even with different combinations of techniques such as refined behavioral testing, electrical recording/interference, and metabolic imaging studies. Verbal object comprehension was studied herein in a single individual, by using three tasks (object naming, auditory word comprehension, and visual word comprehension), two languages (English and Farsi), and four techniques (stimulus manipulation, direct cortical electrical interference, electrocorticography, and a variation of the technique of direct cortical electrical interference to produce time-delimited effects, called timeslicing), in a subject in whom indwelling subdural electrode arrays had been placed for clinical purposes. Electrical interference at a pair of electrodes on the left lateral occipitotemporal gyrus interfered with naming in both languages and with comprehension in the language tested (English). The naming and comprehension deficit resulted from interference with processing of verbal object meaning. Electrocorticography indices of cortical activation at this site during naming started 250-300 msec after visual stimulus presentation. By using the timeslicing technique, which varies the onset of electrical interference relative to the behavioral task, we found that completion of processing for verbal object meaning varied from 450 to 750 msec after current onset. This variability was found to be a function of the subject's familiarity with the objects.

Fibromyalgia and women's pursuit of personal goals: a daily process analysis

For 30 days, 50 women with primary fibromyalgia syndrome reported daily progress and effort toward a health-fitness and a social-interpersonal goal and the extent to which their pain and fatigue hindered their accomplishment. They also carried palmtop computers to assess their sleep and their pain, fatigue, and positive and negative mood throughout the day. Analyses of the person-day data set showed that on days during which pain or fatigue increased from morning to evening, participants perceived their goal progress to be more attenuated by pain and fatigue. Unrestorative sleep the night before predicted the following day's effort and progress toward accomplishing health-fitness goals, but not social-interpersonal goals. Finally, participants who reported more progress toward social-interpersonal goals on a given day were more likely to evidence improvements in positive mood across the day, regardless of any changes in pain or fatigue that day.