Selective removal of Pb2+ by AlPO4

Aluminium(III) phosphate was observed to have a very high selectivity towards Pb2+ ions. Under similar conditions, the sorption capacities of the exchanger were observed to follow the order: Pb2+ > Zn2+ > Ni2+ > Co2+. The potentiometric titration data were used to determine the deprotonation constants (pKa) of AlPO4, which were dependent upon the temperature and nature of the metal cations present in the aqueous phase. Different physical methods i.e. FTIR, EPM and the wet chemical analyses were used to investigate the uptake mechanism of Pb2+ by the solid, which showed that no new solid phases were present in the solid residue after sorption of Pb2+ at pH 5. The exchange between protons from the surfaceand Pb2+ from solutions was found to be responsible for Pb2+ sorption by aluminum(III) phosphate.

Sorption mechanism of Co2+ ions by AlPO4

Sorption studies were conducted for Co2+ ions on AlPO4 at different concentrations and temperatures. Sorption of Co2+ was found to increase with increase in concentration and temperature. To determine the mechanism of the sorption process, dissolution of AlPO4 in the presence of Co2+ ions and desorption studies were performed which indicated the mechanism of sorption to be the ion exchange followed by precipitation. FTIR studies were also employed to confirm the proposed mechanism.

The Sorption of Divalent Metal Ions on AlPO4

The sorption of Cu(2+), Pb(2+), Ni(2+), and Cd(2+) ions on the aluminum(III) phosphate was observed to increase with increases in the concentration, temperature, and pH of the system. The apparent dissociation (pK(a)), binding (pK(b)) and exchange (pK(ex)) constants of aluminum(III) phosphate were evaluated and found to be dependent upon the temperature and nature of the metal cations. The values of the dissociation constants (pK(a)) followed the order Pb(2+)<Cu(2+)<Cd(2+)<Ni(2+)<K(+), opposite to the values of the binding constants and selectivity shown by the solid. Ion exchange between protons from the surface and metal cations from aqueous solution was found to be responsible for the metal ions sorption by AlPO(4). The values of the dissociation (pK(a)) and exchange (pK(ex)) constants were used to estimate the corresponding apparent thermodynamic parameters (DeltaH(o)(diss), DeltaS(o)(diss) and DeltaH(o)(exch), DeltaS(o)(exch)). The values of DeltaH(o)(diss) and DeltaH(o)(exch) were found to be positive, which showed that both the dissociation and exchange processes were endothermic in nature. The DeltaS(o)(diss) and DeltaS(o)(exch) were also found to be positive, which showed that both the deprotonation and exchange processes on the AlPO(4) were entropy driven and spontaneous.

Selective removal of chromates by macroporous exchanger Amberlyst A-21

Sorption studies of chromate on weakly basic macroporous anion exchanger Amberlyst A-21 were performed as a function of pH (2 - 9), temperature (20 - 40 degrees C) and concentration (0.4 - 80 mmol.l(-1)). Chromate sorption was observed to decrease with the increase in initial pH of the solution, with a sorption maxima at pH 2 and increased with the increase in temperature. The changes in pH and in the ratio of choride ions released to chromate ions sorbed suggested that the anion exchange process was accomanied by hydrolysis and Donnan invasion. The FTIR spectra and isoeteric heat of sorption besides showing the hydrolysis / Donnan invasion of resin under different experimental conditions of concentration, pH and temperature also showed the dimerization of the chromate species inside the resin phase.

Cooling is a potent vasodilator of deep vessels in the rat

The objectives of this study were to determine the effect of cooling on smooth muscle tone of the pulmonary artery and aorta and to clarify the basic mechanism of these responses. We recorded isometric tension in smooth muscle strips of rat pulmonary artery and aorta in organ baths during stepwise cooling. Cooling responses were tested before and after the addition of various standard agents that interfere with known neurogenic (autonomic blockers, tetrodotoxin) and myogenic mechanisms (calcium channel blockers) of relaxation. We also examined the hypothesis of the presence of a cooling-released substance. Stepwise cooling (37degrees C to 4 degrees C) of aortic smooth muscle induced reproducible graded relaxations that were inversely proportional to temperature. Cooling-induced relaxation was not dependent on a neural mechanism nor the release of neurotransmitters or a cooling-released substance such as NO or CO. Cooling of pulmonary arterial and aortic smooth muscle preparations induced a graded myogenic relaxation inversely proportional to the cooling temperature. The mechanism is not dependent on local nervous or known mediators but related to a direct physico-chemical effect of cooling.

Rapid identification of neonatal sepsis

OBJECTIVE

To achieve rapid identification of neonatal sepsis.

SETTING

Neonatal Intensive care unit (NICU) of a teaching hospital.

METHOD

We evaluated fifty neonates who were admitted with clinical features suggesting sepsis or who had principal risk factors, e.g. Prematurity (< 36 weeks), Low birth weight (< 2.5 kg), H/o maternal pyrexia or prolonged rupture of membranes, birth asphyxia, unbooked cases or instrumentation. Five tests, i.e., Total Leukocyte Count (T.L.C.), Absolute Neutrophil Count, Immature/Total Neutrophil ratio (I.T. ratio), Platelet count and C-Reactive protein were used for rapid diagnosis of neonatal sepsis.

RESULTS

C-reactive protein (C.R.P.) and absolute Neutrophil count had a sensitivity of over 60% with a specificity of 50%. White blood cell count had a specificity of 93% but a sensitivity of 14%.

CONCLUSION

None of the tests used alone were reliable, but when in combination these five tests may help to diagnose sepsis within a few hours. Also, if the tests show a high negative predictive value, the neonate can be discharged early from the hospital, stopping the antibiotics, thereby reducing the cost of treatment and anxiety of the family.

Neonatal sepsis: an etiological study

OBJECTIVE

A periodic review of neonatal sepsis to asses any change in the infecting organism.

METHOD

A prospective study was conducted at HMC and ASH, Karachi. The babies suspected to have or developed sepsis any time during hospitalization were investigated to establish the diagnosis and isolate the causative organism. Blood culture was taken at the time of admission or when sepsis was suspected.

RESULTS

Out of 109 episodes of blood culture proven sepsis 68 presented as early onset (within 48 hours of birth) and 41 as late onset sepsis (after 48 hours of birth). In early onset group Gram -ve and Gram +ve organisms were almost equal, i.e. 33 and 35 respectively. Among the gram -ve organism most of the cases were due to Klebsiella sp, and Enterococcus was the commonest Gram +ve organism. In late onset group majority of infections were due to gram +ve organisms, i.e. 30 out of 41. Staph. aureus and Staph. epidermidis were commonest. The organisms were least sensitive to Ampicillin (< 20%) and highly sensitive to Amikacin (90% to 100%), Cefotaxime was also seen as a good choice of antibiotic with sensitivity of (84%-89%).

CONCLUSION

Gram +ve organisms were the main cause of neonatal sepsis. Klebsiella sp. is still the commonest organism causing early onset sepsis. The data must be periodically reviewed and antibiotic policy revised accordingly.

Inhibitory effect of capsaicin on cholinergic transmission in ovine airways: evidence for non-cholinergic contractions

Electrical stimulation of ovine trachealis smooth muscle and bronchial ring segments induced neurogenic and monophasic atropine-sensitive contractions. Pretreatment of the tissues with capsaicin (100 microM) significantly reduced these contractions indicating a possible contribution of a peptidergic neurotransmitter to the contractions. The effect of capsaicin on electrically induced contractions was significantly inhibited by capsazepin indicating an action on vanilloid receptors. In both preparations, electrically induced contractions were not modified by tachykinin NK(1)- and NK(2)-receptor antagonists singly and in combination. It was therefore concluded that a component of the atropine-sensitive electrically induced contractions of ovine airways smooth muscles involved the release of a peptide neurotransmitter which is probably not a tachykinin. However, an action of capsaicin on prejunctional vanilloid receptors located on cholinergic nerves cannot be ruled out.

Comparative Sorption Properties of Metal(III) Phosphates

Sorptionbehavior of metal(III) phosphates toward Zn(2+) was investigated using different concentrations, pHs, and temperatures. Ion exchange between protons from the surface and metal cations from solutions was found to be responsible for metal sorption by metal(III) phosphates. Dissociation constants of metal(III) phosphates and binding constants of the Zn(2+) with metal(III) phosphates were determined using Henderson-Hasselbach and modified Langmuir equations, respectively. The sorption process in all the three metal phosphates was found to be endothermic in nature while the dissociation process was observed to be endothermic in AlPO(4) and FePO(4) and exothermic in CrPO(4). Copyright 1999 Academic Press.

Temperature Effect on the Surface Charge Properties of gamma-Al2O3

A comprehensive study of the surface properties of the gamma-Al2O3 in KNO3 as a function of temperature was undertaken potentiometrically. Surface charge, ionization and complexation constants, and PZC were calculated from the potentiometric titration data in the temperature range 293-333 K. A difference between the PZC and CIP was observed as a result of the adsorption of NO-<INF POS="STACK">3 ions. A simple graphical procedure based on the mass action law was used to determine the number of surface sites and equilibrium constants. Thermodynamic parameters, which showed a decrease in the role of nitrate NO-<INF POS="STACK">3 ion in the charging mechanism of gamma-Al2O3, were also evaluated, whereas that of K+ ion increased with the increase in temperature. Copyright 1998 Academic Press.

Clinical features of thrombophilia in families with gene defects in protein C or protein S combined with factor V Leiden

Twenty-nine clinically well-characterized, symptomatic index patients, 15 with protein C and 14 with protein S deficiency, in whom the genetic defect had been identified, were investigated for the presence of factor V Leiden. In six of 15 (40%) propositi with protein C and four of 14 (29%) with protein S deficiency, factor V Leiden was present. The age at first thrombosis was significantly lower (P < 0.001) in the ten propositi with a combined genetic defect (mean age 18.4 +/- 6.6 years) than in those with a single defect (mean age 32.6 +/- 10.4 years). Spontaneous occurrence, recurrence and site of thrombosis were similar in propositi with the single and the combined defect. Family studies led to the identification of a combined defect in 18 individuals from 11 families (11 propositi and 29 relatives), seven subjects had no abnormality, and in 15 a single defect was found. In individuals with a combined defect, thrombosis-free survival time was significantly shorter than in individuals with a single defect, even after exclusion of index patients. None of the seven individuals without genetic abnormality had experienced thrombosis. Our findings indicate a higher risk for development of thrombosis in individuals with a combined defect compared with those with a single defect.

A hitherto unknown splice site defect in the protein S gene (PROS1): the mutation results in allelic exclusion and causes type I and type III protein S deficiency

A hitherto unknown splice site mutation, in the splice acceptor of intron B (tctag to tctgg), was identified in a symptomatic patient with type III protein S deficiency. The mutation co-segregated with type I/III protein S deficiency in the patient's family. RNA analysis showed allelic exclusion of the mutant transcript in affected individuals. The apparent type III deficiency in the propositus was not associated with the protein S Heerlen variant.

A frequent mutation in the protein S gene results in cryptic splicing

Protein S is a vitamin K dependent coagulation inhibitor. One of several defects in the protein S gene (PROS1) associated with hereditary deficiency is a G --> A transition at position 5 of the splice donor in intron J. Although the mutation has been reported to cause allelic exclusion, we demonstrated low amounts of alternatively spliced ectopic PROS1 transcripts in carriers of this mutation. Sequencing of mutant RNA indicated the use of a cryptic splice site upstream of the common splice donor. The use of the cryptic splice site results in the deletion of 32 nucleotides at the 3' end of exon 10. The new reading frame contains several premature termination signals.

Evaluation of dowdo (wheat-milk gruel) in children with acute diarrhoea

Appropriate feeding practices have an important impact on diarrhoeal disease management in developing countries. We evaluated the efficacy of feeding dowdo, a wheat-milk gruel, traditionally used as a weaning food in the Northern Areas of Pakistan. Dowdo was compared with khitchri, a rice-lentil mixture, in acute diarrhoea through a randomized trial. Seventy- six children between 6 and 36 months of age, with acute watery diarrhoea of less than seven days were recruited. After rehydration with standard World Health Organization (WHO) glucose-based oral rehydration solution or intravenous Ringers lactate, patients were randomly assigned to either diet group. Dowdo and Khitchri were found to be equally effective in terms of stool frequency and output, duration of diarrhoea, weight gain and duration of hospitalization. The results indicate that feeding dowdo was as effective as khitchri in children with acute diarrhoea. Additionally, acceptability of dowdo was better than Khitchri. It is recommended that dowdo be used for nutritional management of diarrhoeal disease in children in the Northern Areas of Pakistan.

Two new frequent dimorphisms in the protein S (PROS1) gene

Two new polymorphisms were identified in the protein S gene (PROS1): an intronic T/A-dimorphism (PIPS1) in intron K, and an exonic C/A-dimorphism (PEPS2), located in the 3'untranslated trailer of exon 15. Allelic frequencies of 24% (PIPS1-A) and 17% (PEPS2-A) respectively, were determined in the normal population. The identification of an intronic and an exonic PROS1 dimorphism, in addition to the known BstXI dimorphism, enlarges the molecular tool box for gene analysis and transcript quantification in hereditary protein S deficiency. Haplotype analysis showed that variability of both new polymorphisms occurred almost exclusively in the A-allele of the known intragenic BstXI dimorphism. Therefore, PEPS2 and PIPS1 are especially valuable in individuals homozygous for the BstXI A-variant.

A study of clinical and allergic aspects of rhinitis patients in Riyadh

Eighty consecutive patients presenting with variable nasal symptoms were investigated. Fifty-three (66.25%) were identified as allergic and 27 (33.5%) as having nonallergic rhinitis. Medical history and clinical examination alone seemed to be inadequate in establishing a diagnosis, since the main complaints, i.e., nasal itching, sneezing and runny rose, occurred with the same frequency in both groups. However, alternating nasal blockage and sneezing were prominent in the allergic group (80.40%), while perennial symptoms were more evident in the nonallergic group (68%). There were no striking differences between the two groups in the occurrence of nasal septal deviation or in evidence of nasal polyps. In the allergic groups, sensitivities to indoor allergens, i.e., cockroaches, cat fur, house dust, as well as to pollens, were very prominent. Among the nonspecific provoking factors, dust, strong smells, smoke and stress seem to be important.

Factors affecting size and configuration of electrovaporization lesions in the prostate

OBJECTIVES

Transurethral electrovaporization of the prostate is a new, minimally invasive technique being used by urologists for surgical ablation of prostatic tissue. There are insufficient data concerning factors affecting the vaporization and coagulation lesions produced by this technique. The aim of this study was to determine the role of various parameters for adequate tissue evaporation.

METHODS

This study compared bovine liver and human prostatic lesions made by the Vaportrode instrument with those produced by standard electrocautery loops, roller balls, and laser fibers. Additionally, two electrosurgical instruments with differing technical capabilities were compared for their ability to cause vaporization of tissue.

RESULTS

Results revealed that the Vaportrode lesions were maximal with a new electrode when used with a Force 40S electrosurgical generator set at 300 W and a drag speed of 25 to 30 seconds per 10 mm of tissue. The lesions produced by this technique had a 74% greater coagulation volume compared to a standard cautery loop. The evaporation defect was comparable to a laser lesion produced in contact at 60 W.

CONCLUSIONS

We conclude that electrovaporization under optimal conditions causes a vaporization lesion comparable to that produced by high power density laser prostatectomy. Additionally, the coagulation volume of a vaportrode lesion is considerably greater than that produced by standard electrocautery resection.

Protein S deficiency type I: identification of point mutations in 9 of 10 families

We identified potentially causative mutations in the active protein S gene (PROS 1) by direct sequencing of PROS 1-specific polymerase chain reaction (PRC) products of all 15 exons, including exon-intron boundaries in 10 families with hereditary protein S deficiency type I. Seven different mutations were found in 9 of 10 families, including one frame shift mutation, a previously published splice site mutation (both occurring in two unrelated families), four missense mutations, and a stop codon at the beginning of exon 12. In family studies, cosegregation of the mutation with the disease could be demonstrated for five mutations; for two missense mutations, this was not possible due to limited family data. All seven mutations were the only abnormalities identified in the respective index patients and were absent in 44 to 62 normal individuals. Therefore, they most likely represent the causal gene defects. For five mutations, analysis of ectopic RNA could be performed. Mutant transcripts were present in the case of the frame shift and three of the missense mutations, while no mutant RNA could be detected in the case of the stop codon.

PML-RAR alpha PCR positivity in the bone marrow of patients with APL precedes haematological relapse by 2-3 months

We report the results of serial tests in three patients with hyperleucocytotic AML M3 by haematological methods, coagulation assays and PCR analyses following treatment with ATRA and chemotherapy. All three patients became PCR negative in bone marrow and peripheral blood (sensitivity level 1 in 10(5) cells) after one cycle of ATRA + chemotherapy. However, they relapsed haematologically 6-9 months after achieving complete haematological remission. The haematological relapse was preceded by PCR positivity in the bone marrow by 3 months. Platelet counts decreased already during CHR, but dropped below normal levels only at the time of relapse. Coagulation parameters were not helpful for early prediction of relapse. Our results demonstrate that PCR analysis in the bone marrow is the best way to monitor patients with APL. However, in hyperleucocytotic patients, PCR negativity does not seem to indicate long-term remission.

Effects of dose and interdose interval on locomotor sensitization to the dopamine agonist quinpirole

To assess whether the interval between injections affects the course of locomotor sensitization to quinpirole, groups of rats were injected every 2, 4, or 8 days with quinpirole (0, 0.025, 0.25, 0.5, and 2.5 mg/kg; n = 222) and their locomotor activity monitored after each injection for a total of 10 tests. Results indicate that the number of drug injections, rather than the interval between them, predominantly controls the development of locomotor sensitization to quinpirole. It is suggested that this may reflect a rapid induction but slow decay time for a response-enhancing factor stimulated by each injection of quinpirole, and that the effects of this putative factor are cumulative but saturable.

The contractile response of thiopental in large and small ovine airways

The present study addresses the question of bronchial reactivity towards thiopental using pharmacological assay and ultrastructural analysis with transmission electron-microscopy in sheep airways. Smooth muscle strips of the upper, middle and lower trachea and small size bronchial rings of sheep were investigated using organ bath technique with monitoring of isometric tension in response to thiopental (10(-7)-10(-4)M), histamine (10(-4)M) and carbachol (10(-8)M). Thiopental elicited contractile responses in the large airways, with most marked contractions in the upper trachea. In the small lobar bronchi thiopental caused a biphasic response with predominant relaxation. Similar reactions could be elicited by histamine. Ultrastructural studies showed a large number of mast cells with equal distribution throughout the bronchial tree. Histamine release from bronchial tissue was detected by bioassay after thiopental challenge. It can be concluded that thiopental at a concentration of 10(-4)M releases histamine from mast cells within the airways with consequent constriction in the trachea and mainly dilatation in the smaller intralobular airways. Under these conditions therefore, one does not necessarily expect a net change of airflow resistance with thiopental anaesthesia.

Stretch-induced myogenic responses of airways after histamine and carbachol

The purpose of the study described here was to determine the possible role of a myogenic response of bronchial smooth muscle in deep inspiration (DI)-induced bronchoconstriction. Model experiments were performed on sheep tracheal strips. The effect of sudden stepwise elongation on isometric tension of tracheal muscle was studied in the absence and presence of the bronchoconstrictors carbachol (10(-8) M) and histamine (10(-4) M). In control strips tension increased rapidly with stretch and was followed by stress relaxation which corresponds to creep or bronchial dilatation. In histamine- and carbachol-treated strips a reactive contraction with a rhythmic pattern interrupted the process of stress relaxation. These responses appeared after only 20% elongation and were characteristic of a myogenic contraction which in the in vivo situation would correspond to a bronchoconstriction. These findings are interpreted as a functional transformation of multiple- to single-unit smooth muscle due to the influence of carbachol and histamine. This suggests that stretching (DI) of bronchial smooth muscle in the presence of carbachol and histamine induces a protracted myogenic contraction, which may explain bronchoconstriction after DI in severe asthma.

Isolation and characterization of efficient plasmid transformation mutants of Mycobacterium smegmatis

Recent development of vectors and methodologies to introduce recombinant DNA into members of the genus Mycobacterium has provided new approaches for investigating these important bacteria. While most pathogenic mycobacteria are slow-growing, Mycobacterium smegmatis is a fast-growing, non-pathogenic species that has been used for many years as a host for mycobacteriophage propagation and, recently, as a host for the introduction of recombinant DNA. Its use as a cloning host for the analysis of mycobacterial genes has been limited by its inability to be efficiently transformed with plasmid vectors. This work describes the isolation and characterization of mutants of M. smegmatis that can be transformed, using electroporation, at efficiencies 10(4) to 10(5) times greater than those of the parent strain, yielding more than 10(5) transformants per microgram of plasmid DNA. The mutations conferring this efficient plasmid transformation (Ept) phenotype do not affect phage transfection or the integration of DNA into the M. smegmatis chromosome, but seem to be specific for plasmid transformation. Such Ept mutants have been used to characterize plasmid DNA sequences essential for replication of the Mycobacterium fortuitum plasmid pAL5000 in mycobacteria by permitting the transformation of a library of hybrid plasmid constructs. Efficient plasmid transformation of M. smegmatis will facilitate the analysis of mycobacterial gene function, expression and replication and thus aid in the development of BCG as a multivalent recombinant vaccine vector and in the genetic analysis of the virulence determinants of pathogenic mycobacteria.

Realization of a uniform circular source using a two-dimensional binary filter

A uniform-intensity circular light source has been realized from a Gaussian laser beam by using an area-modulated binary filter. The technique preserves the wave front, and as a result the uniform circular source can be located at a plane perpendicular to the axis of propagation over a wide area.