Synchrotron X-ray phase contrast imaging of leaf venation in soybean (Glycine max) after exclusion of solar UV (280-400 nm) radiation

The hydraulic efficiency of a leaf depends on its vascular structure as this is responsible for transport activities. To investigate the effect of exclusion of UVAB and UVB radiation from the solar spectrum on the micro-structure of leaves of soybean (Glycine max, variety JS-335), a field experiment was conducted using synchrotron-based phase contrast imaging (PCI). Plants were grown in specially designed UV exclusion chambers, and wrapped with filters that excluded UVB (280-315 nm) or UVAB (280-400 nm), or transmitted all the ambient solar UV (280-400 nm) radiation (filter control). Qualitative observation of high-resolution X-ray PCI images obtained at 10 keV has shown the differences in major and minor vein structures of the leaves. The mid-rib width of the middle leaflet of third trifoliate leaves, for all treatments, were obtained using quantitative image analysis. The width of the mid-rib of the middle leaflet of third trifoliate leaves of UVB excluded plants was found to be more compared to leaves of filter control plants, which are exposed to ambient UV. The mid-rib or the main conducting vein transports water and sugars to the whole plant; therefore, mid-rib enhancement by the exclusion of solar UV radiation possibly implies enhancement in the leaf area which in turn causes an increased rate of photosynthesis.

Effect of pneumoperitoneum on intracranial pressure during supratentorial craniotomy: a case report

Laparoscopic surgery has become the method of choice for many procedures previously performed by open techniques. However, its use in patients with a potentially decreased intracranial compliance warrants caution. We report a case of combined glioma excision and laparoscopic cholecystectomy procedures with evaluation of the effects of pneumoperitoneum on ICP and operative field. The clinical implications, safety and recommendations of conducting laparoscopic surgeries in neurosurgical patients are discussed. Performing pneumoperitoneum in patients with marginal intracranial compliance needs interdisciplinary discussions and ICP monitoring is mandatory.

Nanoindentation and scratch studies on magnetron sputtered Ti thin films

Ti thin films sputter deposited on D9 steel at two different temperatures were studied for their mechanical behavior under static and sliding contact conditions using nanoindentation and scratch tests. The film hardness measured at the surface of the coatings exhibited a value of 2.5 GPa, for both conditions. From the scratch test, it is understood that coatings deposited at 200 degrees C substrate temperature showed superior adhesion strength. Critical load to failure for these coatings was evaluated at 2 N.

Microstructural studies of nanocomposite thin films of Ni/CrN prepared by reactive magnetron sputtering

Synthesis and characterization of nanocomposites of Ni/CrN thin films prepared by DC magnetron sputtering from a target of 50 wt.%Ni-50 wt.%Cr is investigated. The films prepared as a function of nitrogen flow rate and substrate temperature showed that the films contained Ni and CrN phases with crystallite sizes in the nanometer range. Measurement of nanomechanical properties of the composite films exhibited a significant decrease in the values of hardness and Young's modulus than those of pure CrN films.

A peptide inhibitor of HIV-1 protease using alpha, beta- dehydro residues: a structure based computer model

HIV-1 encodes an aspartic protease, an enzyme crucial to viral maturation and infectivity. It is responsible for the cleavage of various protein precursors into viral proteins. Inhibition of this enzyme prevents the formation of mature, infective viral particles and therefore, it is a potential target for therapeutic intervention following infection. Several drugs that inhibit the action of this enzyme have been discovered. These include peptidomimetic inhibitors such as ABT-538 and saquinavir, and structure based inhibitors such as indinavir and nelfinavir. Several of these have been tested in human clinical trials and have demonstrated significant reduction in viral load. However, most of them have been found to be of limited clinical utility because of their poor pharmacological properties and also because the viral protease becomes rapidly resistant to these drugs on account of mutations in the enzyme. One way to overcome these limitations is to design an inhibitor that interacts mainly with the conserved residues of HIV-1 protease. By a rational drug design approach based on the high resolution X-ray crystal structure of the HIV-1 protease with--MVT 101 (a substrate based inhibitor) and the specific design principles of peptides containing dehydro-Alanine (delta Ala) derived from our earlier studies, we have designed a tetrapeptide with the sequence: NH2-Thr-delta Ala-delta Ala-Gln-COOH. Energy minimization and molecular modelling of the interaction of the designed tetrapeptide with the inhibitor binding site indicate that the inhibitor is in an extended conformation and makes excessive contacts with the viral enzyme at the interface between the protein subunits. The designed inhibitor has 33% of its interaction with the conserved region of HIV-1 protease which is of the same order as that of MVT 101 with the enzyme.

Tachypnoea is a good predictor of hypoxia in acutely ill infants under 2 months

OBJECTIVE

To evaluate the respiratory rate as an indicator of hypoxia in infants < 2 months of age.

SETTING

Pediatric emergency unit of an urban teaching hospital.

SUBJECTS

200 infants < 2 months, with symptom(s) of any acute illness.

METHODS

Respiratory rate (by observation method), and oxygen saturation (SaO(2)) by means of a pulse oximeter were recorded at admission. Infants were categorised by presence or absence of hypoxia (SaO(2) </= 90%).

RESULTS

The respiratory rate was >/= 50/min in 120 (60%), >/= 60/min in 101 (50. 5%), and >/= 70/min in 58 (29%) infants. Hypoxia (SaO(2) </= 90%) was seen in 77 (38.5%) infants. Respiratory rate and SaO(2) showed a significant negative correlation (r = -0.39). Respiratory rate >/= 60/min predicted hypoxia with 80% sensitivity and 68% specificity.

CONCLUSION

These results indicates that a respiratory rate > 60/min is a good predictor of hypoxia in infants under 2 months of age brought to the emergency service of an urban hospital for any symptom(s) of acute illness.

A peptide inhibitor of HIV-1 reverse transcriptase using alpha,beta-dehydro residues: a structure-based computer model

HIV-1 reverse transcriptase (RT) is a key enzyme involved in the replication of the virus and is a potential target for therapeutic intervention following infection. Several drugs that inhibit the enzyme from acting have been discovered. These include nucleoside-analogue inhibitors such as AZT (zidovudine), ddI and ddC, and non-nucleoside inhibitors such as nevirapine and delavirdine. All of them, however have been found to be of limited clinical utility because the RT becomes rapidly resistant to them on account of point mutations in the enzyme. One way to partly overcome this limitation is to design an inhibitor that has interactions mainly with the backbone and the conserved residues of RT. Using a rational drug-design approach based on the high resolution X-ray crystal structure of the RT-nevirapine complex (1), and the specific design principles of peptides containing dehydro-Alanine (deltaAla) generated by our theoretical calculations, we present here the design of a peptide inhibitor of RT. Energy minimization and molecular modeling of the interaction of the designed pentapeptide with the nevirapine-binding site indicate that the inhibitor has 60% of its interactions with the conserved regions of RT as compared to 30% in the case of nevirapine, thus making it much less sensitive to mutations in the enzyme.

A proteinase K inhibitor using alpha,beta-unsaturated (dehydro) residues: a presumptive model

Enzymes of the subtilisin family, of which proteinase K is a member, have been studied extensively on account of their numerous biological applications. Specific inhibitors of the proteinases are of immense importance in regulating their activity so as to protect the cells against uncontrolled proteolysis. Using the specific design principles of peptides containing dehydro-Alanine (deltaAla), generated by our theoretical calculations, we present here the design of an inhibitor of proteinase K. Energy minimization and molecular modeling of the interaction of the designed tetrapeptide with the recognition site of proteinase K indicate that it is an effective inhibitor.

Hormone profile & polycystic ovaries in acne vulgaris

Thirty women with acne vulgaris, 20 of whom had moderate/severe acne and ten mild acne, and ten controls matched for age were studied. Grade of hirsutism and menstrual irregularities, if any, were recorded. Hormonal measurements included gonadotropins, LH/FSH, prolactin, testosterone and androstenedione in the early follicular phase and progesterone in the luteal phase to assess ovulation. Pelvic ultrasound examination for polycystic ovaries (PCO) was done in all subjects. Sixteen patients with moderate/severe acne and one with mild acne had polycystic ovaries on ultrasound. Patients with moderate/severe acne with polycystic ovaries had high luteinizing hormone, prolactin, testosterone and androstenedione and LH/FSH ratio of more than three. Patients with polycystic ovaries were detected to have at least one hormonal abnormality.

Clinical signs of pneumonia in infants under 2 months

To determine clinical signs that can predict pneumonia (confirmed by radiography) in infants under 2 months of age, 101 infants with pneumonia and 150 with an upper respiratory infection (but not pneumonia) were studied. Ten infants with pneumonia and 15 with an upper respiratory infection did not have the cough and/or difficult (or rapid) breathing that are recommended as 'entry criteria' by the World Health Organisation (WHO). The remaining infants met WHO entry criteria; in them sensitivity and specificity of respiratory rate > or = 60/min and/or severe chest indrawing to diagnose pneumonia was 85% and 97% respectively. Addition of four non-specific signs (stopped feeding well, looked sick, temperature < or = 38 degrees C, and abdominal distension) to respiratory rate > or = 60/min and/or chest indrawing for case identification resulted in a 7% gain in sensitivity but 22% loss of specificity. Addition of nasal flaring improved the sensitivity by 6% without loss of specificity. However, the non-specific signs were the only clue to diagnosis in five infants weighing < or = 2500 g. At age < 7 days, a weight < or = 2500 g and cyanosis were associated with significantly higher risk of mortality. These findings support the use of a respiratory rate > or = 60/min and/or chest indrawing for identification of pneumonia, and suggest addition of nasal flaring to the criteria for case identification in infants under 2 months with cough and/or difficult or rapid breathing.

Validity of clinical signs for the identification of pneumonia in children

In a prospective study to determine simplified clinical signs predictive of pneumonia in children between 2 months and 5 years of age, and to test the validity of the signs recommended by the World Health Organization, clinical findings were correlated with X-ray evidence of pneumonia in 854 children, 400 with pneumonia and 454 with upper respiratory infections (no pneumonia). A respiratory rate of > or = 50/min in infants 2-6 months of age, > or = 40/min in children 7-35 months, and > or = 35/min in children > or = 36 months was the best discriminator of radiological evidence of pneumonia. Use of a respiratory rate of > or = 50/min instead of > or = 40/min resulted in a 14%, 19% and 32% loss of sensitivity with little gain in specificity in the age groups 7-11 months, 12-35 months and > or = 36 months, respectively. The age-specific respiratory rate (recommended by WHO) and/or chest indrawing, history of rapid or difficult breathing and/or chest indrawing, and nasal flaring were also sensitive and specific indicators of pneumonia in almost all the age groups studied.

Learning styles of LD and NLD ADHD children

Attention Deficit Hyperactive Disorder (ADHD) children (N = 26) with a learning disability (LD) and without (NLD) were compared on measures of information processing using the Learning Efficiency Test (LET). Method of presentation (visual vs. auditory), order of recall (ordered vs. non-ordered), and memory processes (immediate, short-term, and long-term) were assessed. While both groups showed more difficulty with short-term and long-term memory processes than with immediate memory processes, the ADHD-LD subjects demonstrated more difficulty processing information effectively. Ordered recall was significantly more difficult for both short-term and long-term memory processes than was unordered recall. While both groups demonstrated difficulty with auditory ordered recall under short-term and long-term conditions, the ADHD-LD subjects lost the most information under auditory conditions.

Effects of two treatment techniques on delay and vigilance tasks with attention deficit hyperactive disorder (ADHD) children

In this study, we examined the effects of two treatment techniques under on-medication and off-medication conditions on the hyperactive behavior patterns of children. Three groups of subjects were compared: a control group, a behavior modification group, and a cognitive training group. The Gordon Diagnostic System (Gordon, McClure, & Post, 1986) was used to assess the subjects at the initial screening, during treatment without medication, and during treatment with medication. The two medication conditions were counterbalanced during the second and third testing sessions. Results showed that when the cognitive intervention was combined with medication, there was a significant improvement in the subjects' ability to delay impulsive responding. However, no significant effects were seen for sustained vigilance for either the behavioral or cognitive groups. Parents rated children in the cognitive group significantly higher than those in the control group.

How are pediatric training programs preparing residents for practice?

The majority of pediatric residents continue to choose a career in practice on completion of their training. Despite knowing residents' career preferences, many training programs have focused on inpatient tertiary care at the expense of primary care. Perhaps this reflects service needs and the significant technology and extensive information resulting in the growth of pediatric subspecialties. To determine the spectrum of didactic and clinical experiences pediatric training programs offer residents to prepare them for managing a practice, we conducted a survey of pediatric training program directors in 1988. Although the majority of residency programs have a practice management curriculum, the number of hours devoted to this area is minimal. In addition, a significant number of residents are not experiencing a community office rotation. This survey indicates the need to develop a practice management curriculum if trainees are to be prepared for choosing the right career and for being competitive in practice.

Postcholecystectomy syndrome in northern India--study on the diagnostic and therapeutic role of ERCP

One hundred and twenty two patients with postcholecystectomy syndrome were studied by endoscopic retrograde cholangiopancreatography (ERCP). The procedure was successful in 105 patients (85.3%) and it accurately detected abnormality of the pancreatico-biliary system in 71 patients (67.6%). ERCP results were abnormal in 82.6% of patients with biliary symptoms, with or without jaundice, compared with 34.7% of patients with non-biliary symptoms (P less than 0.001). Though ERCP showed abnormality in all patients with biliary symptoms and jaundice, as many as 70.4% of patients without jaundice had abnormal ERCP. The commonest abnormality was retained/recurrent stones (37/105 patients). Patients with biliary strictures presented significantly more often with jaundice compared with patients with biliary stones (74.3% vs 22.3%). In 19 of the 37 patients with retained biliary stones endoscopic sphincterotomy was performed and it was successful in 16 patients (84.2%). Our data indicates that ERCP detects the anatomical level as well as the nature of lesion accurately, and is essential and safe in the diagnosis and management of patients with postcholecystectomy syndrome.

Persistence of sleep disturbances in preschool children

The purpose of our study was to determine if common sleep disturbances in young children, such as night waking and bedtime struggle, tend to persist; if they are related to environmental stress factors and are accompanied by other behavior problems; and if their persistence is related to other factors. Sixty children aged 15 to 48 months (mean age 26.4 months) were studied by interviewing their mothers initially and after 3 years. Children with and without sleep disturbances were compared, with the latter serving as the control group. Twenty-five (42%: night waking, 22%; bedtime struggle, 13%; both night waking and bedtime struggle, 7%) of 60 children had sleep disturbances at the initial interview, and of these 25 children, 21 (84%) had persistence of sleep disturbances after 3 years, persistent sleep disturbances had a significant relationship with increased frequency of stress factors in the environment (P less than 0.01). Other generalized behavior difficulties were present in 30% of sleep-disturbed and 19% of non-sleep-disturbed children (P = NS). Co-sleeping (sleeping with a parent or sibling) was noted more frequently in sleep-disturbed (34%) than in non-sleep-disturbed (16%) children. Twenty percent of the mothers at initial interview and 30% at 3-year follow-up perceived their child's sleep disturbances as stressful to them and to their family life. Early identification of the child with sleep disturbances and timely intervention would help both the child and the family.