Wettability of nano-epoxies to UHMWPE fibers

Ultra high molecular weight polyethylene (UHMWPE) fibers have a unique combination of outstanding mechanical, physical, and chemical properties. However, as reinforcements for manufacturing high performance composite materials, UHMWPE fibers have poor wettability with most polymers. As a result, the interfacial bonding strength between the fibers and polymer matrices is very low. Recently, developing so-called nano-matrices containing reactive graphitic nanofibers (r-GNFs) has been proposed to promote the wetting of such matrices to certain types of fiber reinforcements. In this work, the wettability of UHMWPE fibers with different epoxy matrices including a nano-epoxy, and a pure epoxy was investigated. Systematic experimental work was conducted to determine the viscosity of the epoxies, the contact angle between the epoxies and the fibers. Also obtained are the surface energy of the fibers and the epoxies. The experimental results show that the wettability of the UHMWPE fibers with the nano-epoxy is much better than that of the UHMWPE fibers with the pure epoxy.

Molecular understanding of aminoglycoside action and resistance

Aminoglycosides are potent bactericidal antibiotics targeting the bacterial ribosome, where they bind to the A-site and disrupt protein synthesis. They are particularly active against aerobic, Gram-negative bacteria and act synergistically against certain Gram-positive organisms. Aminoglycosides are used in the treatment of severe infections of the abdomen and urinary tract, bacteremia, and endocarditis. They are also used for prophylaxis, especially against endocarditis. Bacterial resistance to aminoglycosides continues to escalate and is widely recognized as a serious health threat. This might be the reason for the interest in understanding the mechanisms of resistance. It is now clear that the resistance occurs by different mechanisms such as prevention of drug entry, active extrusion of drugs, alteration of the drug target (mutational modification of 16S rRNA and mutational modification of ribosomal proteins), and enzymatic inactivation through the expression of enzymes, which covalently modify these antibiotics. Enzymatic inactivation is normally due to acetyltransferases, nucleotidyltransferases, and phosphotransferases. In this review, we focus on the recent concept of molecular understanding of aminoglycoside action and resistance.

Comparison of apoptosis and mortality measurements in peripheral blood mononuclear cells (PBMCs) using multiple methods

Death through apoptosis is the main process by which aged cells that have lost their function are eliminated. Apoptotic cells are usually detected microscopically by changes in their morphology. However, determination of early apoptotic events is important for in vitro (and ex vivo) studies. The main objective of the present study is to find the most sensitive method for apoptosis detection in human peripheral blood mononuclear cells (PBMCs) by comparing six different methods following five different means of immunological stimulation at 3 and 5 days. Each of six apoptosis quantification methods, except the trypan blue exclusion test, is a combination of two stains, one for the specific detection of apoptotic cells and the other for the unspecific detection of dead cells. Values for apoptosis and mortality were compared with a reference method. The choice of apoptosis detection method is more important following 3 days of stimulation than after 5 days of stimulation (P=2x10(-6) versus P=1x10(-2)). In contrast, we find mortality measurements following the different means of stimulation highly significant at both 3 and 5 days (F2.28=7.9, P=1.4x10(-6) at 3 days and F2.28=8.5, P=4.5x10(-7) at 5 days). Variation as a result of the combination of specific PBMC stimulation and the method used to detect apoptosis is reduced considerably with time (F1.58+3.7, P+3x10(-7) at 3 days to F=1.58=0.97, P=0.5 at 5 days). Based on Tukey's test, YO-PRO-1 is the most sensitive stain for apoptosis and, when combined with 7-AAD, provides an accurate measure of apoptosis and mortality. In conclusion, we propose YO-PRO-1/7-AAD as a new combination and low-cost alternative for the sensitive detection of early apoptosis.

Molecular targets for design of novel inhibitors to circumvent aminoglycoside resistance

Aminoglycosides are a class of clinically important antibiotics used in the treatment of infections caused by Gram-positive and Gram-negative organisms. They are bactericidal, targeting the bacterial ribosome, where they bind to the A-site and disrupt protein synthesis. Antibiotic resistance is a growing problem for all classes of anti-infective agents. One of the first groups of antibiotics to encounter the challenge of resistance was the aminoglycoside -aminocyclitol family. Initially, the resistance that emerged in organisms such as Mycobacterium tuberculosis was restricted to modification of the antibiotic targets, which we now know to be the bacterial ribosomal rRNA and proteins. As new aminoglycosides came to the clinic, however, the prevalence of chemical modification mechanisms of resistance became dominant. Enzymatic modification of aminoglycosides through kinases (O-phosphotransferases, APHs), O-adenyltransferases (ANTs) and N-acetyltransferases (AACs) has emerged in virtually all clinically relevant bacteria of both Gram-positive and Gram-negative origin. Although their clinical use has been extensive, their toxicity and the prevalence of resistance in clinical strains have prompted the pharmaceutical industry to look for alternatives. Whereas the search for novel targets for antibiotics from the genomic information is ongoing, no antibacterial agent based on these efforts has so far entered clinical trials. Meanwhile, structural knowledge of the ribosome, the target for aminoglycosides, has invigorated the field of antibiotic development. It is expected that knowledge of the binding interactions of aminoglycosides and the ribosome would lead to concepts in drug design that would take us away from the parental structures of aminoglycosides in the direction of different structural classes that bind to the same ribosomal target sites as aminoglycosides. The challenge to ensure the continued use of these highly potent antibacterial agents will require the effective management of resistance at several levels. One potential mechanism of circumventing resistance is the development of inhibitors of modification enzymes, a methodology that is now well established in the beta-lactam field. This approach requires knowledge of resistance at the molecular and atomic levels for the rational design of inhibitory molecules. The understanding of the molecular basis for aminoglycoside resistance modification has been greatly enhanced by the recent availability of representative 3D-structures from the three classes of modifying enzymes: kinases, acetyltransferases and adenyltransferases. The challenge is now to firmly establish the mechanisms of enzyme action and to use this information to prepare effective and potent inhibitors that will reverse antibiotic resistance. In this review, we discuss the molecular mechanisms of resistance of aminoglycosides specifically on aminoglycoside-modifying enzymes and newly developed strategies to circumvent resistance including antisense technology, which is an example of new strategy to deal with antibiotic resistance.

Polymorphism of HIV-1 gag (p17) gene from female sex workers in Calcutta, India

HIV-1 subtype C is the major subtype in India as evidenced from the analysis of specific regions within envelope and gag gene. The matrix protein (p17) of HIV-1 which is involved in several functions like the viral RNA transport, nuclear localization, assembly of pre-integration complex into host nucleus has been used to study the strain diversity among female sexworkers in Calcutta. The gene encoding for the HIV-1 matrix protein, p17 was amplified by nested polymerase chain reaction (PCR) from blood samples of HIV-1 seropositive female sex workers (FSW) in Calcutta, India. Genes of twenty-two samples were sequenced and the phylogenetic analysis with different global strains showed that the majority (seventeen) was clustered with Indian type C. A few samples were found to be close to other C subtypes isolated from South Africa, China and Myanmar. The comparison of Calcutta samples with the samples from other regions of India along with other non-asian subtype C sequences clearly revealed a different cluster of Indian sequences. The two samples, cal 242 and cal 709 was found to be the most divergent type and showed close relatedness with African C subtypes.

Strategies for efficient production of heterologous proteins in Escherichia coli

In recent years, the number of recombinant proteins used for therapeutic applications has increased dramatically. Production of these proteins has a remarkable demand in the market. Escherichia coli offers a means for the rapid and economical production of recombinant proteins. These advantages, coupled with a wealth of biochemical and genetic knowledge, have enabled the production of such economically therapeutic proteins such as insulin and bovine growth hormone. These demands have driven the development of a variety of strategies for achieving high-level expression of protein, particularly involving several aspects such as expression vectors design, gene dosage, promoter strength (transcriptional regulation), mRNA stability, translation initiation and termination (translational regulation), host design considerations, codon usage, and fermentation factors available for manipulating the expression conditions, which are the major challenges is obtaining the high yield of protein at low cost.

RNA interference: potential therapeutic targets

One of the most exciting findings in recent years has been the discovery of RNA interference (RNAi). RNAi methodologies hold the promise to selectively inhibit gene expression in mammals. RNAi is an innate cellular process activated when a double-stranded RNA (dsRNA) molecule of greater than 19 duplex nucleotides enters the cell, causing the degradation of not only the invading dsRNA molecule, but also single-stranded (ssRNAs) RNAs of identical sequences, including endogenous mRNAs. The use of RNAi for genetic-based therapies has been widely studied, especially in viral infections, cancers, and inherited genetic disorders. As such, RNAi technology is a potentially useful method to develop highly specific dsRNA-based gene-silencing therapeutics.

Detection and characterization of HIV type 2 in Calcutta, India

Since the first report of HIV/AIDS in India in 1986, continuous serosurveillance has been undertaken in all Indian states. Recently, five cases of HIV-2 infection have been detected in Calcutta, situated in the eastern part of India. The full-length envelope gene (2.5 kb) of one of the strains was amplified, cloned, and sequenced. Phylogenetic analysis of the Calcutta HIV-2 envelope revealed a close relatedness to the HIV-2 Rod sequence isolated in offshore Senegal. This strain, however, showed a genetic diversity of 13.5% to other Indian HIV-2 isolates.

Comparative evaluation of clindamycin phosphate 1% and clindamycin phosphate 1% with nicotinamide gel 4% in the treatment of acne vulgaris

Eighty patients with moderate acne vulgaris were enrolled from out-patient department for the comparative evaluation of clindamycin phosphate 1% and clindamycin phosphate 1% with nicotinamide gel 4%. In group I forty patients were given clindamycin phosphate 1% alone.ln group II forty patients were given clindamycin phosphate 1% and nicotinamide gel 4% in combination. The study did not show any added advantage of clindamycin phosphate 1% in combination with nicotinamide gel 4% over clindamycin phosphate 1% alone.

HIV type 1 subtypes circulating in eastern and northeastern regions of India

Genetic subtyping has been a powerful tool in tracking the global spread of HIV. To determine the HIV-1 subtypes circulating in eastern and northeastern regions of India blood samples were collected from female sex workers in Calcutta and intravenous drug users (IDUs) in Manipur. Fifty-four samples from Calcutta and 25 samples from Manipur were analyzed for HIV-1 subtyping by heteroduplex mobility assay (HMA). Twenty-six samples from these regions were sequenced. HMA and sequencing of the samples from these regions revealed subtype C as the major subtype, circulating within both eastern and northeastern regions. In Manipur, subtype ThaiB was also detected as the second major subtype. Some of the IDUs from Manipur were found to be dual infected with subtype C and ThaiB.

Zinc supplementation as adjunct therapy in children with measles accompanied by pneumonia: a double-blind, randomized controlled trial

BACKGROUND

Zinc deficiency, common in developing countries, is associated with decreased immunocompetence. Zinc supplementation benefits children with acute and persistent diarrhea and prevents pneumonia. Most deaths from vaccine-preventable diseases are from measles and whooping cough; pneumonia is the most common complication of measles and often the proximate cause of related deaths.

OBJECTIVE

We evaluated the effect of zinc supplementation on episodes of illness in children with measles accompanied by pneumonia.

DESIGN

In a double-blind, randomized controlled trial, children aged 9 mo-15 y who were admitted to the Infectious Diseases Hospital in Calcutta with clinically severe measles accompanied by pneumonia and who had been ill for </= 7 d were randomly assigned to receive zinc (20 mg, in elemental form as acetate, twice daily for 6 d) or a placebo. All patients received standard treatment with antibiotics and an initial 100 000-IU dose of vitamin A (as palmitate) by mouth.

RESULTS

Time-to-event analysis using the Cox proportional hazards model (42 in the zinc group and 43 in the placebo group) showed that the time needed for the resolution of fever and tachypnea, the return of appetite, and the achievement of a "much improved" or "cured" status was not different between the 2 groups. A high proportion of children had low serum retinol and zinc concentrations. Improvement in serum zinc and retinol concentrations after 6 d of treatment was not different between the 2 groups.

CONCLUSION

Children with severe measles accompanied by pneumonia treated with antibiotics and vitamin A did not show any additional benefit from also receiving a zinc supplement.

Species relationships in Fagopyrum revealed by PCR-based DNA fingerprinting

Random amplified polymorphic DNA (RAPD) markers were used to distinguish between 28 different accessions belonging to 14 species and two sub-species of Fagopyrum. Of the 75 random 10-mer primers tested, only 19 generated robust, easily interpretable amplification products. A total of 364 bands were observed with an average of 19.15 bands per primer, of which 99.45% were polymorphic. Primer OPN-08 produced the maximum number of fragments and UBC-183 produced the minimum number of fragments. The data were utilized to elucidate genetic relationships among 14 species and two sub-species of Fagopyrum. Cluster analysis using the unweighted paired group method of arithmetic means (UPGMA) showed four main clusters, two each of the cymosum and urophyllum groups. The results showed that Fagopyrum tataricum is closer to its wild ancestor F. tataricum ssp. potanini Batalin, closely followed by Fagopyrum giganteum. Cultivated common buckwheat ( Fagopyrum esculentum) showed affinity with its putative wild ancestor F. esculentum ssp. ancestrale and the other closely related diploid species Fagopyrum homotropicum. In the urophyllum group, Fagopyrum macrocarpum and Fagopyrum pleioramosum formed one cluster, whereas Fagopyrum capillatum, Fagopyrum gracilipes and Fagopyrum gilessii clustered separately. Except for a few cases, our results correspond with previously reported studies on Fagopyrum using the isozyme, RFLP and RAPD methods. Species-diagnostic amplification products specific to some species in the cymosum and urophyllum groups were identified. Our results show that RAPDs can be successfully used to analyze species relationships in Fagopyrum and also for constructing linkage maps.

Measuring the impact of needle exchange programs among injecting drug users through the National Behavioural Surveillance in Bangladesh

Bangladesh is a low HIV prevalence country, with buprenorphine injectors having the highest prevalence of HIV at 2.5% as of 1999. Using National HIV Behavioral Surveillance data, the impact of a needle exchange program (NEP) on sharing behavior among injecting drug users in two cities was measured. Results showed positive changes that varied with the different settings. Those who reported utilizing the NEP were compared with those who did not. Differences in Dhaka were significant for the average proportion of needles shared but not for the proportion of men who ever shared in the last week. In Rajshahi, where professional injectors were the norm, the impact of an NEP was greater and affected both the proportion of needles shared as well as the proportion of men never sharing. Behavioral surveillance methods have the potential to measure intervention impact through comparative analysis in certain settings.

Neck and whole-body scanning with 5-mCi dose of (123)I as diagnostic tracer in patients with well-differentiated thyroid cancer

OBJECTIVE

To determine whether a 5-mCi dose of 123I can be used as an effective radiotracer for assessing the presence of remnant thyroid tissue and for searching for metastatic lesions in patients with well-differentiated thyroid cancer as well as to attempt to ascertain whether a scan performed only at 4 hours is sufficient for accurate diagnosis and might replace the conventional protocol of scanning at both 4 hours and 24 hours.

METHODS

We prospectively studied 27 patients who had undergone near-total thyroidectomy and had a documented diagnosis of well-differentiated thyroid carcinoma. Patients underwent scanning after receiving a 5-mCi dose of 123I, at a time when they had discontinued thyroid replacement therapy and had a thyrotropin level in excess of 30 mIU/mL. Whole-body images at 4 hours and 24 hours were obtained and were compared with posttherapy scans obtained 5 to 7 days after administration of 131I. Scans were interpreted by two board-certified nuclear medicine physicians.

RESULTS

Of the 27 patients, 2 (7.4%) showed discordance between the 123I scan performed at 24 hours and the posttherapy 131I scan. When 4-hour images after administration of 123I were compared with the posttherapy 131I scans, a discordance rate of 14.8% (4 of 27 patients) was noted. In addition, two of these four patients showed lesions on the 24-hour images that were not seen on the 4-hour images (one with new lung metastatic involvement and the other with a local recurrence in the lower neck area). The prognosis and treatment of these two patients were substantially changed by the result of the 24-hour images.

CONCLUSION

On comparison of scans obtained after administration of a 5-mCi dose of 123I with those obtained after 131I therapy, we conclude that 5 mCi of 123I produces images that have excellent quality and resolution and also compare favorably with those obtained after 131I therapy. Furthermore, a decrease in the dose of 123I from 10 mCi to 5 mCi lowered the cost of the study without compromising the diagnostic accuracy or image quality. Finally, use of 24-hour images will occasionally disclose additional areas of radioiodine uptake not detected on the 4-hour scans and is therefore recommended.

Prevalence of human papillomavirus infection among prostitutes in Calcutta

We investigated the presence of human papilloma virus (HPV) 16/18 and herpes simplex virus-1,-2 (HSV-1,-2) infections in buccal mucosal cells of prostitutes of Calcutta, India, by in situ DNA hybridization and immunocytochemical technique. In some of them, we also examined the prevalence of viral infections in uterine cervical cells. The women were also tested for venereal disease research laboratory antigen (VDRL) positivity. Oral infections with HSV-1, -2 and HPV 16/18 were detected in 24.6%, 11.6%, and 29%, respectively. Similar cervical infections were found in 0%, 44%, and 62.9% of the cases studied. HPV coinfection was significantly higher (p < 0.01) in both the oral and cervical cells that had HSV infection. The cervical HPV infections were not markedly higher among the VDRL-positive prostitutes (p > 0.05). The HPV or HSV infection rates showed no remarkable variation between the two age groups of the prostitutes studied (p > 0.05). Cytological abnormalities were more pronounced in the cervix of women having concurrent infection with HPV and HSV-2 rather than in the presence of infection with either of the two. This preliminary investigation, the first of its kind in India, requires a larger study to understand the significance of the association of different sexually transmitted agents including HPV (apart from HIV) as risk factors for pathologic lesions.

Metastatic thyroid cancer occurring as an unknown primary lesion: the role of F-18 FDG positron emission tomography

Thyroid cancer can appear as metastatic disease of an unknown primary origin, and fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomographic (PET) studies are helpful in the workup evaluation of these patients. The authors describe two patients who had metastatic disease from an unknown primary lesion. F-18 FDG PET studies played an important role in localizing the primary malignant site in the thyroid gland. The utility of F-18 FDG imaging in decreasing the number of procedures, cost, and inconvenience to patients is shown clearly in both cases.

Role of repeated F-18 fluorodeoxyglucose imaging in management of patients with bone and soft tissue sarcoma

AIM OF THE STUDY

To assess the impact of repeated F-18 FDG studies on the management of patients with bone and soft tissue (B&S) sarcomas.

MATERIAL AND METHODS

Twenty patients with B&S tissue tumors (11 M and 9 F age 17-72 years) had 52 F-18 FDG Dual Head Coincidence Imaging (DHCI) studies. 7 patients were followed for 6 months to 2 years clinically after removal of the primary tumor. Thirteen patients were evaluated for suspected recurrences. Patient's preparation, F-18 FDG injection and imaging procedure were done according to department protocol. Attenuation corrected images were interpreted visually by 3 trained physicians. Tumor to background ratios were calculated for all lesions.

RESULTS

In 13 patients having both studies, baseline FDG and CT/MRI were concordant in 8 patients, FDG detected more lesions in 3 patients but it did not detect 4 metastatic pulmonary nodules in 2 patients. Follow up studies showed stable disease in 10 patients while 6 patients who showed worsening disease needed to change their chemotherapy. Surgery was avoided in 2 patients and 2 patients showed improved response.

CONCLUSION

Repeated F-18 FDG DHCI examinations proved to have an impact on the clinical management of patients with malignant bone and soft tissue sarcoma. It helps to differentiate postoperative changes from local recurrence.

Distribution of HIV-1 subtypes in female sex workers of Calcutta, India

BACKGROUND & OBJECTIVES

Different routes for the transmission of HIV-1 in India have been reported and the majority of infections occurred through heterosexual route of transmission. In order to understand the dynamics of HIV-1 transmission, a systematic study was undertaken to determine the viral subtypes circulating among the female sex workers in Calcutta, India.

METHODS

Peptide enzyme immunoassay (PEIA), heteroduplex mobility assay (HMA) and DNA sequence analysis were used to ascertain the HIV-1 subtypes.

RESULTS

V3 serotyping of 52 HIV-1 seropositive samples identified 33 (60%) to be subtype C. A DNA fragment within C2-V3/C2-V5 regions of HIV-1 gp120 was amplified directly from the lymphocyte DNA to avoid any bias in selecting viral variants and used in HMA. Of the 40 samples analyzed, 38 (95%) belonged to subtype C and 2 were found to be non-typable. Further analysis of these 38 samples revealed that 26 (68%) had maximum homology to the C3-Indian reference strain (IND868), 11 (29%) were most homologous to C2-Zambian strain (ZM18) and 1 (3%) showed close resemblance to C1-Malawi strain (MA959). Nucleotide sequence of 11 subsamples encompassing about 325 base pairs was aligned for the Indian and other geographically distinct isolates. On distance and parsimony trees, most of the samples (8/11) clustered together as subtype C.

INTERPRETATION & CONCLUSIONS

Subtype C was the major circulating HIV-1 strain in this geographical region, although variation within this subtype was also noticed. DNA sequence analysis was found to be the best method in determining the nature of the HIV-1 subtype followed by HMA and peptide enzyme immunoassay. These findings may have important implications for the design of effective vaccines in India and emphasizes the need for constant monitoring of the HIV-1 subtypes in different parts of India.

Tc-99m MAG3 scintigraphy in unusually dilated bilateral extrarenal pelves

The authors report the findings of a radionuclide diuretic renogram in a patient with markedly dilated pelves bilaterally that filled most of the abdominal cavity. With the patient in the sitting position, at the end of the furosemide injection, there was good delineation and filling of the dilated calyces. These findings are unusual because of the extensive pelvicaliceal dilatation, and they emphasize the importance of the sitting position.

Unusual presentation of solitary bone metastasis from breast carcinoma mimicking acute osteomyelitis of the left midtibial shaft

The authors report an unusual presentation of a solitary bone metastasis in the left midtibial shaft with no other skeletal involvement in a patient with breast carcinoma. The incidence of solitary bone metastasis below the knees is rare. Clinically, the lesion was tender when palpated. A bone scan revealed increased blood flow and blood pool activity, with intense midtibial bony uptake in delayed images. These findings are similar to those of acute osteomyelitis. Biopsy revealed bony metastasis from the patient's breast carcinoma.

Discrepancy between Ga-67 citrate and F-18 fluorodeoxyglucose positron emission tomographic scans in pulmonary infection

The authors describe a patient with the acquired immunodeficiency syndrome who had active pulmonary tuberculosis and was receiving anti-tuberculosis treatment. High-grade fever and a right-sided pleural effusion had recently developed. Results of a Ga-67 scan were negative for any focal infection in the chest. Fluorine-18 fluorodeoxyglucose positron emission tomography showed increased uptake in the right lower lung field, which correlated with the diagnosis of concomitant bacterial pneumonia. Anti-tuberculosis treatment can decrease the sensitivity of the Ga-67 scan and could have contributed to this discrepancy. The authors predict that the fluorine-18 fluorodeoxyglucose positron emission tomographic scan will play an important diagnostic role in the management of such a selected group of patients.