Pulmonary tuberculosis at Patan Hospital, Nepal: One year audit

Background

Globally, Tuberculosis (TB) is one of the top 10 causes of death. In Nepal, poverty and malnutrition aggravate the burden of TB. To identify Mycobacterium tuberculosis sputum is the best sample to identify the bacterium which is helpful for diagnosis. The aim of this study is to identify the situation, burden and challenges of pulmonary tuberculosis in low-middle income country like Nepal.

Method

A retrospective-audit with reliable-secondary-data of one year was collected (n = 4131). Descriptive-analysis was performed using frequency, percentage and analytical using chi-square-test. Level of significance was set at p < 0.05. Ethical Approval was obtained from IRC-PAHS.

Result

The prevalence of notified/suspected cases was highest among the patients having >60 years of age 1344(32.54%) and least among the patients with ≤15 years of age 239(5.79%). The male had 1.67 times more smear-positive pulmonary TB cases. Among the AFB-positive cases, smear 3+ was seen in most of the cases 69(38.54%) followed by smear 1+ and smear 2+ in 56(31.28%) and 54(30.16%) respectively.

Conclusion

The prevalence of smear-positive pulmonary TB case is higher in male. Smear 3+ is seen in most of the followed by smear 1+ and smear 2+. The Burden of Pulmonary TB is more among adult and old-age-people and its control is a challenge for developing and low-middle income countries like Nepal.

Impacts and challenges of United States medical students during the COVID-19 pandemic

The delivery of medical student education has changed rapidly during the coronavirus disease 2019 (COVID-19) pandemic. Students in their pre-clinical years have transitioned to online courses and examinations. Students in their clinical years are not permitted on clinical rotations, and face uncertainties in career exploration and the residency application process. Medical students in all stages of training are volunteering and helping their communities. The future presence of COVID-19 throughout the United States is unknown, and medical students are eager to return to their training. This paper outlines current challenges in medical student education and the various responses that have been adopted. We also discuss possible future directions for students through involvement in telemedicine, outpatient clinic visits, and non-respiratory inpatient care tasks as adequate personal protective equipment, COVID-19 testing, and resources become more widely available.

Vascular access in kidney transplant recipients

Vascular access is an important element in the overall care provided to kidney transplant recipients. The transplanted kidney is not indestructible, and chronic kidney disease after transplantation may result in needing another transplant or beginning dialysis. Commonly used vascular accesses, like peripheral and central lines, can preclude the creation of future, permanent dialysis access. Therefore, there is urgent need to preserve vessels for the future access needs for hemodialysis among kidney transplant recipients without functional vascular access for dialysis. Moreover, the proper care of functional vascular access among kidney transplant recipients is crucial. In this review article, we will address the common vascular access procedures and complications among kidney transplant recipients.

SU-E-T-462: Calculation of Prescribed Dose for Permanent Implant with Cs-131 Using LQ Equation including Resensitization

PURPOSE

To develop a new biological equivalent dose (BED) formulism that includes repair, repopulation and resensitization (redistribution and reoxygenation), and can be used to calculate prescribed dose for permanent implant with Cs-131.

METHODS

Because of lack of sufficient clinical data, the prescribed dose with new isotopes is usually calculated based on BED compared with other isotopes that have already been used in clinical practice. The current widely used formulism of BED calculation for permanent implant which was given by Dale includes cell repair and repopulation but not resensitization. Resensitization can be included in the extended LQ equation (LQR) proposed by Brenner. Applying Dales formulism to Brenners LQR, we obtained a new BED calculation formula that accounts for resensitization. We used this new formulism to calculate the BED that corresponds to the prescribed dose for cervix (with Au-198) and prostate (with I-125) permanent implant. Then, we obtained the prescribed dose with Cs-131 which has the same BED as Au-198 or I-125.

RESULTS

The new formulism was used for prostate and cervix cancer permanent implant. The prescribed dose with Cs-131 for cervix was 40 Gy (42 Gy without resensitization) and 66 Gy (69 Gy without resensitization) which were equivalent to 35 Gy and 60 Gy with Au-198, respectively. For prostate implant, the prescribed dose with Cs-131 that corresponded to 144 Gy with I-125 was 135 Gy (124 Gy without resensitization).

CONCLUSION

Resensitization led to significant dose correction for permanent implant. The calculation of BED and dose was dependent on dose itself and thus should be patient-specific. Since this calculation relied on many biological parameters, and may not be accurate if the parameters are not accurate. Also, the dose prescription should be adjusted based on clinical outcomes.

Metabolic activation of heterocyclic amines and other procarcinogens in Salmonella typhimurium umu tester strains expressing human cytochrome P4501A1, 1A2, 1B1, 2C9, 2D6, 2E1, and 3A4 and human NADPH-P450 reductase and bacterial O-acetyltransferase

We investigated roles of different forms of cytochrome P450 (P450 or CYP) in the metabolic activation of heterocyclic amines (HCAs) and other procarcinogens to genotoxic metabolite(s) in the newly developed umu tester strains Salmonella typhimurium (S. typhimurium) OY1002/1A1, OY1002/1A2, OY1002/1B1, OY1002/2C9, OY1002/2D6, OY1002/2E1 and OY1002/3A4, which express respective human P450 enzymes and NADPH-cytochrome P450 reductase (reductase) and bacterial O-acetyltransferase (O-AT). These strains were established by introducing two plasmids into S. typhimurium TA1535, one carrying both P450 and the reductase cDNA in a bicistronic construct under control of an IPTG-inducible double tac promoter and the other, pOA102, carrying O-AT and umuC"lacZ fusion genes. Expression levels of CYP were found to range between 35 to 550 nmol/l cell culture in the strains tested. O-AT activities in different strains ranged from 52 to 125 nmol isoniazid acetylated/min/mg protein. All HCAs tested, and 2-aminoanthracene and 2-aminofluorene exhibited high genotoxicity in the OY1002/1A2 strain, and genotoxicity of 2-amino-3-methylimidazo [4,5-f]quinoline was detected in both the OY1002/1A1 and OY1002/1A2 strains. 3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]-indole and 3-amino-1-methyl-5H-pyrido[4,3-b]-indole were activated in the OY1002/1A1, OY1002/1B1, OY1002/1A2, and OY1002/3A4 strains. Aflatoxin B(1) exhibited genotoxicity in the OY1002/1A2, OY1002/1A1, and OY1002/3A4 strains. beta-Naphthylamine and benzo[a]pyrene did not exhibit genotoxicity in any of the strains. These results suggest that CYP1A2 is the major cytochrome P450 enzyme involved in bioactivation of HCAs.

Use of genetically engineered Salmonella typhimurium OY1002/1A2 strain coexpressing human cytochrome P450 1A2 and NADPH-cytochrome P450 reductase and bacterial O-acetyltransferase in SOS/umu assay

The major pathway of bioactivation of procarcinogenic heterocyclic aromatic amines (HCAs) is cytochrome P450 1A2 (CYP1A2)-catalyzed N-hydroxylation and subsequent esterification by O-acetyltransferase (O-AT). We have previously reported that an umu tester strain, Salmonella typhimurium OY1001/1A2, endogenously coexpressing human CYP1A2 and NADPH-P450 reductase (reductase), is able to detect the genotoxicity of some aromatic amines [Aryal et al., 1999, Mutat Res 442:113-120]. To further enhance the sensitivity of the strain toward HCAs, we developed S. typhimurium OY1002/1A2 by introducing pCW"/1A2:hNPR (a bicistronic construct coexpressing human P450 1A2 and the reductase) and pOA102 (constructed by subcloning the Salmonella O-AT gene in the pOA101-expressing umuC"lacZ gene) in S. typhimurium TA1535. In addition, as an O-AT-deficient strain, we developed the OY1003/1A2 strain by introducing pCW"/1A2:hNPR and pOA101 into O-AT-deficient S. typhimurium TA1535/1,8-DNP. Strains OY1001/1A2, OY1002/1A2, and OY1003/1A2 expressed, respectively, about 150, 120, and 140 nmol CYP1A2/l culture (in whole cells), and respective cytosolic preparations acetylated 15, 125, and > or = 0 nmol isoniazid/min/mg protein as the O-AT activities of cytosolic preparations, respectively. We compared the induction of umuC gene expression as a measure of genotoxicity and observed that the OY1002/1A2 strain was more sensitive than OY1001/1A2 strain toward the genotoxicity of 2-amino-1,4-dimethylimidazo[4,5-f]quinol ine(MeIQ), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ),2-amino-3, 8-dimethylimidazo[4,5-f]quinoxaline (MeIQx),2-aminoanthracene, 2-amino-6-methyldipyrido[1,2-a::3,2'-d]i midazole,3-amino-1, 4-dimethyl-5H-pyrido[4,3-b]indole, and 3-amino-1-methyl-5H-pyrido[4, 3-a]indole. However, the genotoxicity of MeIQ, IQ, and MeIQx was not detected with the OY1003/1A2 strain. These results indicate that the newly developed strain OY1002/1A2 can be employed in detecting potential genotoxic aromatic amines requiring bioactivation by CYP1A2 and O-acetyltransferase.

Development of a new genotoxicity test system with Salmonella typhimurium OY1001/1A2 expressing human CYP1A2 and NADPH-P450 reductase

In order to develop a new tester strain detecting environmental promutagens and procarcinogens, we introduced two plasmids into Salmonella typhimurium TA1535; one contains the cDNAs of human cytochrome P450 (P450 or CYP) 1A2 and NADPH-P450 reductase and the other (pOA101) a umuC"lacZ fusion gene. The newly developed tester strain, S. typhimurium OY1001/1A2, was found to express P450 at a level of 0.15 nmol/ml in whole cell culture. Membrane fractions, when isolated from this tester strain, contained 0.04 P450 nmol/mg protein and a reductase activity of 170 nmol cytochrome c reduced/min/mg protein and were active in catalyzing CYP1A2-dependent 7-ethoxyresorufin O-deethylation and metabolic activation of heterocyclic aromatic amines to DNA-damaging products in a conventional tester S. typhimurium NM2009 strain, only when NADPH was added as a reducing equivalent. In the OA1002/1A2 strain, heterocyclic aromatic amines (e.g., IQ, MeIQ, and MeIQx) were found to be activated to reactive metabolites that cause induction of umuC gene expression in a dose-dependent manner, without addition of external NADPH. These results indicate that the newly established strain can be of use to detect mutagenic and carcinogenic potencies of environmental chemicals without addition of metabolic activation system.