Depression mediates the relationship between exposure to stigma and medication adherence among people living with HIV in low-resource setting: a structural equation modeling approach

This study hypothesizes that depression mediates the association between exposure to stigma and medication non-adherence in people living with HIV (PLHIV). We recruited 372 PLHIV from the Stigma, health-related Quality of life, antiretroviral Adherence, and Depression among people living with HIV (SQuAD-HIV) project, a multicenter cross-sectional study conducted between October 2021 and February 2022 among PLHIV attending six ART clinics in two geopolitical regions of northern Nigeria. A structural equation modeling (SEM) framework, utilizing the full information maximum likelihood estimator, was used to elucidate the pathways linking stigma, depression, and ART medication adherence, adjusting for sociodemographic characteristics. The total number of eligible participants analyzed (353) included 32.7% male PLHIV with a mean age (SD) of 39.42 (10.14). Being female was positively associated with adherence (β, 95% CI 0.335, 0.163-0.523, p-value < 0.001) but negatively associated with stigma (β, 95% CI - 0.334, - 0.561 to - 0.142, p-value = 0.001), while urban residence was negatively associated with stigma (β, 95% CI - 0.564, - 0.804 to - 0.340, p-value < 0.001). Our analysis also indicated that a higher level of experienced stigma was associated with decreased medication adherence. This association was partially mediated by depression (indirect effect = (0.256) (- 0.541) =  - 0.139; p-value < 0.01). The proportion of the association between stigma and medication adherence explained through mediation by depression was 35.6%. These findings underscore the need for targeted interventions aimed at lowering exposure to stigma among PLHIV to improve medication adherence.

COVID-19 vaccine hesitancy among people living with HIV in a low-resource setting: A multi-center study of prevalence, correlates and reasons

BACKGROUND

Hesitancy to COVID-19 vaccine may worsen the burden of COVID-19 among people living with HIV (PLHIV), who are at a higher risk of COVID-19-related hospitalization and death, compared to HIV non-infected individuals. Therefore, we evaluate the predictors and reasons for COVID-19 vaccine hesitancy among unvaccinated PLHIV in six antiretroviral therapy (ART) clinics across northern Nigeria.

METHODOLOGY

In this cross-sectional study, conducted between October 2021 and February 2022 in six hospitals across two geopolitical regions of Nigeria, we utilized interviewer-administered questionnaires to assess COVID-19 vaccine hesitancy among a convenience sample of 790 eligible adult PLHIV. Hesitancy was defined as answering 'no' or 'maybe' to a question asking participants their willingness to accept the COVID-19 vaccine. A multivariate logistic regression model was used to estimate the adjusted odds ratio (aOR) and 95% confidence interval (CI) of the factors associated with COVID-19 vaccine hesitancy among PLHIV.

RESULTS

Of the total 660 unvaccinated participants included in the analysis (61.82% female, mean age [SD] of 39.76 [10.75]), 381 (57.72%) were hesitant to COVID-19 vaccine. Being 50 years and older (aOR: 0.43; 95% CI: 0.21-0.89), being unemployed (aOR: 0.57; 95% CI: 0.34-0.95), experiencing the adverse effects of ART (aOR: 0.36; 95% CI: 0.15-0.86), and perception of being at high risk of contracting COVID-19 (aOR: 0.22; 95% CI: 0.13-0.37) were associated with significantly lower odds of hesitancy. Conversely, being female (aOR: 1.64; 95% CI: 1.02-2.61) and attending ART clinics at state administrative capital cities (IIDH Kano [aOR: 2.40; 95% CI: 1.10-5.25], MMSH Kano [aOR: 5.59; 95% CI: 1.97-10.66], YSSH Damaturu [aOR: 9.88; 95% CI: 4.02-24.29] vs. GH Gashua) were associated with significantly higher odds of hesitancy. The most common reasons for hesitancy include fear of potential adverse effects, skepticism about vaccine efficacy, the rapid development of the COVID-19 vaccine, and the perceived lack of effort to develop a cure or vaccine for HIV/AIDS.

CONCLUSION

Interventions aimed at combating misperceptions and misinformation regarding the COVID-19 vaccination program may reduce the prevalence of COVID-19 vaccine hesitancy among unvaccinated PLHIV.

Prevalence, determinants, and reasons for malaria vaccine hesitancy among caregivers of under-five children in Nigeria: Results from a nationwide cross-sectional survey

OBJECTIVE

Malaria contributes to an enormous global burden of disease and mortality, especially in children. Approximately one in every four global cases and deaths from malaria occurs in Nigeria. This study aims to evaluate the prevalence and correlates of community hesitancy to the malaria vaccine, including the reasons for the hesitancy, following the approval of the RTS,S malaria vaccine by the World Health Organization (WHO).

METHODS

This was a nationwide cross-sectional online survey of Nigerian adults conducted from 20th October to 30th November 2021. Participants who replied 'no' or 'maybe' to a question assessing their willingness to accept the RTS,S malaria vaccine were considered "hesitant". We fit a multivariate logistic regression model to report the adjusted odds ratio (aOR) and 95 % confidence interval (CI) for the factors associated with vaccine hesitancy.

FINDINGS

Among 3377 total respondents (1961 [57.86 %] males; mean age [SD]: 30[9.1]), 1010 (29.91 %) were hesitant. Receiving information about the RTS,S malaria vaccine initially from healthcare workers (vs. the internet) (aOR:0.55; 95 % CI:0.35-0.87) was significantly associated with lower odds of hesitancy. Conversely, earning a high income of over NGN100, 000 (vs. < NGN 30,000) per month (aOR: 2.10, 95 % CI: 1.36-3.24), belonging to other religious groups (vs. Islam) (aOR:3.25, 95 % CI:1.18-8.98), and having a family size of more than ten (vs. < 5) (aOR:1.84; 95 % CI:1.08-3.13) were significantly associated with a higher odds of hesitancy. The main reasons for vaccine hesitancy included fear of vaccine adverse effects (34.95 %), availability of other malaria preventive measures (33.96 %) and not seeing the positive effect of the vaccine in others first (32.97 %).

CONCLUSION

The findings of this survey provide a valuable blueprint for the development of targeted interventions to facilitate caregiver acceptance of the RTS,S vaccine.

Anticandidal activity of ethanolic root extract of Juglans regia (L.): Effect on growth, cell morphology, and key virulence factors

The emergence of drug-resistant strains has encouraged several studies on natural products with antifungal activity and low toxicity. In this study, the antifungal effect of methanolic root extract of Juglans regia (JRE) was investigated against 9 strains of Candida (one reference and 8 clinical strains) through MIC₉₀ and spot assays. To gain insight into the mechanism of antifungal action, we carried out confocal scanning laser microscopy (CLSM), transmission electron microscopy (TEM), and then examined the effect of JRE on hydrolytic enzyme secretion. Additionally, JRE was subjected to various phytochemical tests, chemically characterized by gas chromatography-mass spectrometry analysis (GC-MS) and its toxicity was tested against H9c2 rat cardiac myoblasts. The phytochemical tests showed the presence of phenols, alkaloids, steroids, saponins, and tannins in JRE. In the GC-MS analysis, a total of 40 compounds were identified. JRE was found to be effective in liquid media with MICs ranging from 300 to 700μg/mL. Spot assay results revealed that Candida cells show increased sensitivity to JRE. CSLM experiments showed that cells exposed to JRE (MIC) exhibited cell membrane disruption. TEM micrograph of treated cells showed extensive breakage in the cell wall and cell membrane. Average inhibition of proteinase and phospholipase secretion (of five C. albicans strains) at MIC/2 values of JRE was 45.17%, and 34.29%, respectively. Cellular toxicity of JRE against H9c2 rat cardiac myoblasts was less than 10% at the highest MIC value. These findings encourage further development of JRE.

Near-ultraviolet photolysis of beta-phenylpyruvic acid generates free radicals and results in DNA damage

Ultraviolet A (UVA) light (315-400 nm) is ubiquitously found in our environment and constitutes about 95% of the total solar UV; all UVC and most UVB being absorbed by the stratospheric ozone layer. Compared with UVB and C, UVA does not show any direct effect on biological systems. Indirect effects of UVA, however, have been recognised overwhelmingly and this includes photosensitization of biological and non-biological compounds and production of free radicals many of which include oxygen and are hence known as reactive oxygen species or ROS. Several types of free radicals have been identified although their impacts on various macro- and micro-biomolecules are yet to be fully elucidated. beta-Phenylpyruvic acid is ubiquitously found in eukaryotic cells as a metabolite of phenylalanine, which is subsequently converted to phenyllactate and/or to 2-hydroxyphenylacetate and mandelate. In patients suffering from phenylketonuria the hydroxylation of phenylalanine to tyrosine is defective due to lack of phenylalanine hydroxylase. These result in accumulation and excretion of this compound in the urine. Here we present evidence that photolysis of beta-phenylpyruvic acid by a skin tanning lamp, emitting 99% UVA (315-400 nm) and 1% UVB (290-315 nm) generates carboxyl radicals (CO(2)(*)) and also possibly causes direct electron transfer (or type 1) reactions. Electron paramagnetic resonance was used to detect the free radicals. To determine the biological effects of this photolytic reaction, T7 was exposed to these photolytic reactive agents and found to lead to high levels of phage inactivation. Damage to DNA and/or components such as tail fibre proteins may be involved in T7 inactivation. In addition, our unpublished data suggest that certain phenylketonuria cell lines are more sensitive to PPA+NUV, lending importance to photolytic studies of this agent.

Clinical investigation of hypoglycemic effect of seeds of Azadirachta-inidca in type-2 (NIDDM) diabetes mellitus

The present study was designed to investigate clinically the hypoglycemic effect of seeds of Azadirachta indica in Type-2 diabetes mellitus. After assaying fasting plasma and urinary glucose, 10 patients of type-2 diabetes mellitus with no previous medication, 10 patients of type-2 diabetes mellitus taking oral hypoglycemic agents with history of inadequate control and six control subjects were given low (0.5 g tid) and high (2 g tid) doses of powdered part, aqueous extract and alcoholic extract of Azadirachta indica for 14 days. On 15th day blood and urine samples for glucose were taken. Based on results obtained it was found that Azadirachta indica has significant hypoglycemic activity in high dose and can be successfully combined with oral hypoglycemic agents in type-2 diabetic patients whose diabetes is not controlled by these agents.

Near-ultraviolet photolysis of L-mandelate, formation of reactive oxygen species, inactivation of phage T7 and implications on human health

Compared with ultraviolet B and C, UVA is considered to have little direct effects on biological systems. However, damaging effects of UVA on biological systems are often synergistically enhanced in the presence of sensitizers. Production of reactive oxygen species (ROS) has been implicated in the process. Several ROS have been identified but their involvement in inducing cellular damage is yet to be fully evaluated. Although membranes and proteins are affected, DNA is an important target and a variety of types of damage have been reported. Here, we present evidence that L-mandelate can act as a near UV (NUV) sensitizer, when activated by a lamp emitting 99% UVA and 1% UVB. Although evidence is available that H(2)O(2) and a small amount of *OH are produced, an alternative effect of the sensitization reaction may involve direct electron transfer. Studies have shown that NUV photolysis of mandelate can inactivate phage T7. Employment of tetrazolium blue test to detect superoxide anion may not be sufficient evidence as this agent may be reduced by alternative routes.

Serum lipids and lipoproteins in patients with documented coronary artery disease

Levels of various lipoprotein subclasses can provide useful information on coronary artery disease (CAD) risk status, even when traditional risk factors are known. Elevated serum level of lipids, lipoproteins and lipoprotein (a) have been identified as risk factor for atherosclerosis resulting in coronary artery disease, cerebrovascular disease, peripheral vascular disease and venous thromboembolism. The objective of this study is to evaluate the levels of serum lipids, lipoprotein and lipoprotein (a) in-patients suffering from documented coronary artery disease and normal healthy subjects. A case control study was conducted to evaluate the levels of lipid, lipoprotein and lipoprotein (a) in patients from our local population suffering from documented coronary artery disease. The present study was earned out in Dr. HMI Institute of Pharmacology & Herbal Sciences in collaboration with National Institute of Cardiovascular Diseases, Karachi from January 2001 to June 2001. One hundred and fifty persons were included in this case control study. Out of these one hundred were patients suffering from documented (coronary angiography done 4 month before the study) coronary artery disease (mean age 46.38 +/- 1.38, 18 females and 82 males). 50 normal healthy subjects (mean age, 44.86 +/- 1.15, 2 females and 48 males) had no history of IHD ever before. Their serum lipid, lipoprotein and lipoprotein (a) were estimated and compared.

Treatment of post-burns bacterial infections by Fenton reagent, particularly the ubiquitous multiple drug resistant Pseudomonas spp

Post-burn microbial infections are a major problem in burns, and in cases of third degree burns, the survival of patients can depend not only upon the severity but also upon the extent and the type of infections. If proper measures are not employed, patients may suffer from opportunistic bacterial attacks, which can vary from simple infection, such as those easily treatable by antibiotics, to more complicated types, which may have natural or acquired resistance to drugs. Infection by multiple drug resistant (MDR) bacteria can create further complexity to the treatment. It is proposed that a combination of diluted hydrogen peroxide (H(2)O(2)) and ferrous sulphate (FeSO(4)), which generates hydroxyl radicals (*OH) via Fenton reaction, can effectively be used for the treatment of post-burns bacterial infections. It should be particularly useful for the ubiquitous opportunistic pathogen, Pseudomonas aeruginosa, known to be notoriously resistant to various antibiotics. This reactive oxygen species (ROS)-induced inactivation of the bacterial skin infections may be of particular importance in Third World countries where the incidence of burns and post-burns infections by MDR bacteria (due to the indiscriminate use of antibiotics, lack of stringent safety regulations and proper hygiene) may be more prevalent and where cocktails of antibiotics may be less affordable. Also, since the putative lack of development of bacterial resistance to *OH is not known, it provides an added advantage to the treatment. Finally, although this work addresses the control of bacterial infections in burns cases, it is envisaged that this ROS-induced chemotherapy may also be useful in combating other kinds of skin infections particularly those resisting antibiotic treatment.

Circadian variation--increased morning incidence of acute myocardial infarction in patients with coronary artery disease

OBJECTIVE

To examine whether a circadian variation exists in the onset of symptoms of Acute Myocardial Infarction (AMI) in patients with Coronary Artery Disease (CAD) and to review the characteristics of such variation.

SETTING

Patients with AMI admitted to the coronary care units of two teaching hospitals in the city of Karachi, Dr. Ziauddin Medical University Hospital and National Institute of Cardiovascular Disease.

METHOD

The study population included patients admitted to the coronary care unit. The diagnosis was based on the onset of AMI signs and symptoms and ECG changes. The inclusion criterion was an age less than 76 years.

RESULTS

The incidence of Myocardial infarction assessed by the onset of clinical symptoms exhibited a marked circadian variation. Myocardial infarction occurred 2.8 times more frequently during morning hours (period of maximum incidence) as compared to evening (period of minimum incidence).

CONCLUSION

This result extends previous observation of the circadian variation in the incidence of AMI onset. This study also helps in searching the potential triggers to physiological changes that may occur during morning hours. Design and timing of cardioprotective medication may play a crucial role in improving circadian variation and prevention of AMI.

Treatment of post-burns bacterial infections by bacteriophages, specifically ubiquitous Pseudomonas spp. notoriously resistant to antibiotics

Post-burn microbial infections are a major problem in recovering from the trauma of third-degree burns, and the survival of patients can depend upon the severity of the burn and the infections encountered. Within 24 hours, patients can start suffering from opportunistic bacterial attacks, which can vary from simple infection, such as those easily treatable by antibiotics, to more complicated types, which may have natural or acquired resistance to drugs. Infection by multiple drug-resistant bacteria can create additional complexity to the problem. As an alternative to treating bacterial infections by antibiotics, bacteriophages have been in use in certain parts of the world, such as at Tbilisi in Georgia and in Poland, and this approach has now been more widely recognized. Results have shown that phage therapy has an 80% success rate against Enterococcus infections and up to 90% against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Here it is proposed that bacteriophages can effectively be used for the treatment of post-burn infections, particularly the ubiquitous opportunistic pathogens, Pseudomonas spp., known to be notoriously resistant to a variety of antibiotics. This kind of treatment may be of particular importance in Third World countries where the incidence of burns and infections, due to lack of stringent safety regulations and proper hygiene respectively, may be more common and where cocktails of antibiotics may be less affordable. Phages that can possibly be employed in the treatment and their advantages compared to the use of antibiotics are also highlighted.

Hypotensive effect of chemical constituents from Aloe barbadensis

Hypotensive effects of aloeemodin, aloin A, elgonica dimer A and bisbenzopyran from Aloe barbadensis have been studied. Aloeemodin has emerged as a potent hypotensive agent in current pharmacological investigations and caused 26 %, 52 %, and 79 % falls in mean arterial blood pressure at the corresponding doses of 0.5, 1, and 3 mg/kg in rats. The paper also describes the absolute configuration of elgonica dimer A (1).

Control of skin infections by a combined action of ultraviolet A (from sun or UVA lamp) and hydrogen peroxide (HUVA therapy), with special emphasis on leprosy

Despite its abundance and certain therapeutic value, the importance of sunlight in the treatment of infectious skin diseases has not been fully exploited. One reason is that a sufficient amount of the damaging components of sunlight (UVC and most UVB) cannot reach us and the band of UV that can reach (UVA) is a poor inactivator of living cells. UVA, however, can be deleterious to cells in the presence of sensitizers and a number of biological and chemical sensitizers have been identified which can inactivate microbes in the presence of UVA. Of several known agents, I have selected hydrogen peroxide (H(2)O(2)) as a UVA sensitizer and propose that a combined action of H(2)O(2)and UVA (HUVA therapy) can be utilized in controlling skin infections of various types. Of particular interest is infection by Mycobacterium leprae, which is known to affect many millions of humans globally. H(2)O(2)being relatively cheap (and UVA from the sun being free) the cost of application, particularly in third-world countries where leprosy is more common, would be low and therefore the treatment can be employed on a wide scale. A further reason for proposing the use of H(2)O(2)is that, out of several agents we have tested, this was found to be the most potent; it is also easily able to reach target sites, very cheap, relatively safe and there is no known microbial resistance to HUVA.

Hydrogen peroxide: a potent cytotoxic agent effective in causing cellular damage and used in the possible treatment for certain tumours

H2O2, a highly reactive agent, can react under certain conditions with a variety of cellular components. These reactions include the lipid peroxidation of membrane and hydroxylation of proteins and DNA. The reactions can take place in the presence of oxygen and are fairly rapid, the H2O2 being converted to water and oxygen. Experiments were carried out in vitro to assess the ability of this agent to destroy cancer cells without generating dangerous by-products. The direct administration of aqueous H2O2 into solid tumours has the potential to cause tumour cell death. The efficacy of the use of H2O2 for treating 'solid' cancers will necessitate its delivery to the tumour site, for example by direct special multiple injection of H2O2 into a detectable tumour mass. We anticipate that, if suggested mode of delivery can be obtained, H2O2 can act as an anti-cancer drug with two distinct advantages over conventional chemotherapeutic agents: to produce minimal short- and long-term side-effects and is relatively cheap and cost effective.

Antibiotic susceptibility of Streptococcus pneumoniae in Karachi

OBJECTIVE

To evaluate, record and analyse the comparative activity of a range of oral antibiotics against Streptococcus pneumoniae.

SETTING

Specimen collected at a private laboratory and some received from different hospitals and clinics.

MATERIALS

The specimen comprised of Sputum, Throat Swabs, C.S.F., Pus, Pleural fluid, Ear Swabs, Eye Swabs, Bronchial Wash, Prostatic discharge and Antral Secretions.

METHODS

The isolates were tested for their antibiotic susceptibility using the E-test by the methods described in the study protocol. The groups of antibiotics tested were Amoxicillin--Clavulanate, Clarithromycin, Cefaclor, Cefuroxime, Ceftriaxone and Penicillin.

RESULTS

A total of 116 strains of Streptococcus pneumoniae were isolated and susceptibility to Amoxicillin-Clavulanate was 100%, 99.1% strains were susceptible to Cefuroxime and 0.9% were intermediate. Susceptibility to Penicillin was 80.2% and 19.8% of the strains were in intermediate category, while susceptibility to Clarithromycin was 89.7%, 1.7% were in intermediate region and 8.6% of the strains were resistant to this antibiotic. The susceptibility pattern of Cefaclor was not calculated as there is no current NCCLS--97 Cefaclor breakpoints available.

CONCLUSION

The percentage of drug resistant Streptococcus pneumoniae was negligible in Karachi during the study period, however it is important to monitor the susceptibility pattern to keep a check on an increase in the number of DRSP as reported at different centres in Turkey, Saudi Arabia, Singapore, Thailand, Hong Kong and Indonesia.

Hypotensive, hypoglycaemic and toxicological studies on the flavonol C-glycoside shamimin from Bombax ceiba

Shamimin, a C-flavonol glucoside from Bombax ceiba leaves showed significant potency as a hypotensive agent at the doses of 15 mg/kg, 3 mg/kg, 1 mg/kg and significant hypoglycaemic activity at 500 mg/kg in Sprague-Dawley rats. Further studies revealed that it did not cause any mortality in mice at the dose of 1 g/kg but in rats 500 mg/kg is a lethal dose. Aqueous and methanolic extracts of Bombax ceiba leaves and one of its fractions were also subjected to pharmacological and toxicological screening.

Thymine metabolism and thymineless death in prokaryotes and eukaryotes

For many years it has been known that thymine auxotrophic microorganisms undergo cell death in response to thymine starvation [thymineless death (TLD)]. This effect is unusual in that deprivation of many other nutritional requirements has a biostatic, but not lethal, effect. Studies of numerous microbes have indicated that thymine starvation has both direct and indirect effects. The direct effects involve both single- and double-strand DNA breaks. The former may be repaired effectively, but the latter lead to cell death. DNA damaged by thymine starvation is a substrate for DNA repair processes, in particular recombinational repair. Mutations in recBCD recombinational repair genes increase sensitivity to thymineless death, whereas mutations in RecF repair protein genes enhance the recovery process. This suggests that the RecF repair pathway may be critical to cell death, perhaps because it increases the occurrence of double-strand DNA breaks with unique DNA configurations at lesion sites. Indirect effects in bacteria include elimination of plasmids, loss of transforming ability, filamentation, changes in the pool sizes of various nucleotides and nucleosides and in their excretion, and phage induction. Yeast cells show effects similar to those of bacteria upon thymine starvation, although there are some unique features. The mode of action of certain anticancer drugs and antibiotics is based on the interruption of thymidylate metabolism and provides a major impetus for further studies on TLD. There are similarities between TLD of bacteria and death of eukaryotic cells. Also, bacteria have "survival" genes other than thy (thymidylate synthetase), and this raises the question of whether there is a relationship between the two. A model is presented for a molecular basis of TLD.

Isolation and analysis of UV and radio-resistant bacteria from Chernobyl

The accident at the Chernobyl nuclear power station in 1986 led to the dispersal of large amounts of a variety of radioactive materials, most importantly uranium, plutonium, 137Cs, 131I and 90Sr, over very large distances estimated to reach as far as Sweden, Norway, Turkey and possibly the USA. As a consequence, the soil on which the radioactive materials fell was contaminated and the degree of contamination varied with distance from the station, the direction and strength of the wind and the amount of atmospheric scavenging by rainfall at that time. Some of the radioactive materials have left a significant impact on mankind in the form of chromosomal aberrations including trisomy, various forms of cancers and death, whilst others are still in the ground where they will remain for a prolonged period to continue to exert their effects. Likewise, microbes living in the soil and exposed to radioactive materials may have been affected in a number of ways; some perished, and others survived due to the acquisition of advantageous mutation. Six years after the accident, soil samples contaminated with different levels of radioactivity were obtained from five regions within a 30 km radius of the nuclear power plant. From these soil samples spore-forming bacilli were isolated, quantified, identified and tested for resistance to X-rays, UVC and 4-nitroquinoline 1-oxide (4NQO). As a control, spore-forming bacilli were obtained from 'Zeleny mys' (an area 50 km south-east of the power station and emitting basal levels of radioactivity). A mutant of Escherichia coli hyper-resistant to a variety of DNA-damaging agents and its parent strain were also included in the study. Analysis of results reveals that a proportion of isolates of the same species from near the power station and the E. coli mutant SA236 were more resistant to X-rays, UVC and 4NQO compared with isolates from the control site and the E. coli parent strain, KL14, respectively.

Generation of reactive oxygen species from the photolysis of histidine by near-ultraviolet light: effects on T7 as a model biological system

Near-ultraviolet (NUV) light (280-400 nm) has a variety of effects on biological systems; these effects are increased, often synergistically, in the presence of sensitizers. A variety of both man-made and naturally occurring sensitizers have been identified, but their precise roles and relative contributions to cellular damage are not yet fully established. DNA seems to be a major target and a variety of types of damage have been observed. In this report we present evidence that histidine can also act as a sensitizer of NUV. Upon NUV photolysis a variety of reactive oxygen species, including superoxide anions, hydroxyl radicals and hydrogen peroxide, are produced as determined by the effects of various scavengers. pH influences the reaction, alkaline media being most effective, as has previously been reported for the photolysis of H2O2, tyrosine, phenylalanine and tryptophan. Exposure of phage T7 to a combination of histidine and NUV leads to synergistic inactivation and scavengers of O2.-, .OH and H2O2 reduce this effect. These results point to a possible involvement of sunlight-induced histidine photolysis in cellular damage. The fact that photolysis is maximal at high pH indicates that biological effects are likely to be highly localized, e.g., at enzyme active sites.

[Hyperrecombination of plasmids is characteristic for hyperresistant strains of Escherichia coli]

Intraplasmid recombination frequency was assessed in several Escherichia coli K12 strains by the kinetic bioluminescence method. Enhanced plasmid recombination was observed in two mutant E. coli K12 strains, which were hyperresistant to DNA-damaging agents, gamma-rays, photosensitizer 8-methoxypsoralen. Plasmid recombination frequency per one generation (P) was calculated. In mutant strains, this value was shown to exceed that in control isogenic strains with a standard resistance approximately by a factor of 15. Enhanced constitutive synthesis of specific proteins such as heat-shock proteins in Gamr444 and a 55-kDa protein in SA270 in hyperresistant mutant strains is assumed to promote activity of the recombinational RecF pathway system.

Partial-area method in bioequivalence assessment: naproxen

Regulatory authorities require demonstration of bioequivalence through comparisons of different pharmacokinetic parameters, the area under the plasma concentration-time curve (AUC), the maximum plasma concentration (Cmax), and the time to reach peak concentration (Tmax). The applicability and validity of regulatory requirements have been widely criticized on statistical and clinical relevance grounds. For most noncomplicated absorption models, the AUC correlates well with the extent of absorption. However, in nonlinear models of absorption, in mechanisms involving recycling of drugs, and for drugs with long half-life, the use of total AUC (from zero to infinity) can give erroneous and clinically irrelevant results since the area is mostly determined by elimination phase or by recycling. The calculation of total AUC also involves prolonged sampling, adding to the cost and risks associated with bioequivalence studies. The use of Cmax or Tmax as a measure of rate of absorption, to correlate with clinical relevance, is widely criticized on logical, technical, and statistical grounds. For drugs used on a multiple-dose basis, Cmax and Tmax evaluations become redundant since the average plateau concentration is not affected by these parameters. To resolve the drawbacks in the traditional methodology of bioequivalence evaluation, the use of partial areas in lieu of total AUC, Tmax, and Cmax is suggested. This study investigates the logic and robustness of the partial-area method in establishing bioequivalence. We conclude that the 5h AUC is a more relevant parameter to establish naproxen bioequivalence than AUCinf. We recommend against using symmetrical confidence intervals and report excellent agreement among several methods of calculating confidence intervals, probability values, and nonparametric tests. We suggest that a single-point short-term AUC is a better indicator of the bioequivalence of generic products than the total AUC, Cmax, and Tmax as required currently by the regulatory authorities.

A mutant of Escherichia coli hyper-resistant to a number of DNA damaging agents: location of the mutational site

A mutant of Escherichia coli, isolated as hyper-resistant to UVC, is found to be hyper-resistant to UVA, H2O2, low concentrations of nalidixic acid, novobiocin, UVA plus H2O2 and UVA plus 8-methoxypsoralen. A mutational site (uvh) conferring the hyper-resistance phenotype to UVC, and presumably to other DNA damaging agents, has been mapped at the 89.9 min region on the chromosome. Complementation analysis with an F-prime uvh+/uvh- diploid strain showed that the uvh+ allele is dominant over uvh- in trans. Studies with a variety of plasmids, carrying various LexA regions, introduced into the UV hyper-resistant strain show that mutation at the uvh locus may be responsible for derepression of the SOS inducible repair system. Based on the results, it is suggested that uvh is a part of the SOS inducible system. A plausible explanation for the hyper-resistance phenotypes for various DNA damaging agents and a model for the genetic control of a second set of putative SOS regulons are presented.

Dose dependent pharmacokinetics of naproxen in man

The pharmacokinetics of one of the most widely used non-steroidal antiinflammatory drugs, naproxen, were studied in 28 healthy human volunteers at the two most commonly used dose levels, viz., 250 mg and 500 mg, in a cross-over design. The plasma levels of naproxen were analysed by a modified high-pressure liquid chromatography method. The plasma concentrations at higher doses were not proportional to dose, indicating a non-linearity in the pharmacokinetics at the dose levels studied; this finding is new since earlier studies had studied only higher doses and assumed that at lower doses the pharmacokinetics would be linear. There was, however, no significant difference in the elimination half-life (rate constant), time to reach peak concentration (Cmax), mean residence time (MRT), or area under first moment curve (AUMC). The clearance and distribution volume of naproxen were substantially increased at higher dose resulting in statistically lower proportional concentration and the total area under the curve (AUC). These observations are explained on the basis of a change in the plasma protein binding resulting in more free naproxen available for quicker clearance and wider penetration into tissues. These findings have several important clinical implications for the long-term use of naproxen as an antiarthritic drug. It is proposed that the clinical efficacy of naproxen can be increased and side-effects reduced by giving it in small divided doses instead of large doses.

Plasma membrane sialoglycoproteins of human corneal epithelium in culture

A number of studies, using either rat or rabbit models, have focused on delineating the role of cell surface glycoconjugates in corneal epithelial cell migration and wound healing. We have recently identified the cell surface sialoglycoproteins of rabbit corneal epithelium and have shown that the levels of at least three membrane glycoproteins are markedly altered during cell migration. Because species-related differences may be present, it is important to select an appropriate animal model for studies designed to contribute to the understanding of the mechanism of human corneal wound healing. The purpose of this study was to identify the cell surface sialoglycoproteins of human corneal epithelium. Plasma membrane sialoglycoproteins of primary cultures of human corneal epithelium were labeled with NaB3H4 after oxidation by mild NaIO4 treatment. The labeled glycoproteins were analyzed by SDS-polyacrylamide gel electrophoresis and fluorography. Four different preparations of human corneal epithelial cell cultures were analyzed, and results were compared with those of rabbit corneal epithelium. Of the 11 radiolabeled sialoglycoproteins we identified recently in rabbit corneal epithelium, eight were also present in human corneal epithelium. These similarities in the electrophoretic patterns of the plasma membrane glycoproteins of the two species suggest that rabbit is most likely an appropriate animal model for studies designed to contribute to the understanding of the structure and function of cell surface glycoproteins of human corneal epithelium.

Repair of phage lambda DNA damaged by near ultraviolet light plus 8-methoxypsoralen

Treatment of phage lambda with 8-methoxypsoralen plus near ultraviolet light (PUVA) and its subsequent infection and growth on various mutant and non-mutant hosts were investigated. A number of Escherichia coli DNA repair-deficient mutants, particularly those deficient in genes producing proteins known to participate in interstrand crosslink repair, were used as hosts to assess the roles of these gene products in the activation of phage affected by PUVA. Results show that puvA, uvrA, uvrD, recA, recO, sulA and recN of E. coli are involved in the repair process. Based on the data presented it is proposed that phage lambda DNA is repaired, following PUVA damage, using the recombinational repair process. This may be in agreement with the recombinational model of the repair of E. coli DNA.

Biochemical alterations during swimming induced stress

Stress can be defined as any stimulus that creates an imbalance in the internal environment. Hypothalamus has sensors that detect changes produced in the body. Stress can cause diseases by altering immune system, cardiovascular System neurotransmitter and neuroendocrine functions. Present study is designed to evaluate the effect of stress on few biochemical parameters during swimming induced stress. Significant changes have been observed especially in lipid profile. Corticosterone was also evaluated as reliable stress marker.

Synergistic action of near-UV and phenylalanine, tyrosine or tryptophan on the inactivation of phage T7: role of superoxide radicals and hydrogen peroxide

Near ultraviolet (NUV) light can cause a variety of damage to biological systems. The effects of NUV are significantly enhanced in the presence of sensitizers. One of the most important targets of such synergistic effects is DNA. Cellular DNA exposed to NUV plus sensitizers is damaged in a variety of ways, DNA strand breaks and interstrand cross-links being the most common effects. In this study, phenylalanine, tyrosine and tryptophan are shown to act as sensitizers for NUV action of phage T7; superoxide anions are produced. The reactive species probably interacts with phage DNA causing damage responsible for phage inactivation. Superoxide dismutase reverses the synergistic activities of phenylalanine and tyrosine on NUV-induced phage inactivation, but catalase is additionally required to reverse the effect of tryptophan. Therefore, it is probable that NUV photolysis of tryptophan causes the production of superoxide ions and hydrogen peroxide, both of which contribute to phage inactivation. The ubiquitous nature of NUV in our environment and the presence of amino acids in skin cells suggests that an important mechanism for the induction of skin cancer in humans by solar exposure is amino acid photolysis by NUV.

SAFETY EVALUATION OF ICTERENE - A HERBAL MEDICINE (III. Histopathological consideration)

In earlier studies (Zafar et al., 1993; Ahmed at al. 1993) on safety evaluation of Iceterne, it has been observed that the drug doesn't cause any side effect as far as biochemical and hematological parameters are concerned. Present study is an extension in the same direction through histopathologic approach.

Studies on griseofulvin: part-ii effects on the liver and kidney of albino rat

Studies were performed on albino rats to investigate any untoward effects of griseofulvin on their liver and kidneys. Animals weighing between 200-250g were selected and divided into control and test groups. Griseofulvin was administered to the test groups at a dose level of 20 mg/Kg/day for 2, 46 and 8 weeks respectively. Animals wee sacrificed at the end of their respective study periods for collection of blood and removal of the liver and kidneys. Histopathological examination of the liver and kidneys of the treated animals at the end of 4 and 8 weeks of griseofulvin administration showed no cytotoxic changes. It was, therefore, concluded that griseofulvin has no hepatotoxic effects in albino rats at a dose level of 20 mg/Kg/day.

DNA damage by 8-methoxypsoralen plus near ultraviolet light (PUVA) and its repair in Escherichia coli: genetic analysis

Mutants of Escherichia coli, hyper-resistant and sensitive to 8-methoxypsoralen plus near ultraviolet light (PUVA) have been isolated and studied. Results show that a mutation, located at 57.2 min on the linkage map of E. coli, is responsible for the hyper-resistant phenotype. It is also responsible for the synthesis of a 55-kdal protein in high concentrations. In a wild-type cell the synthesis of this enzyme is inducible by mitomycin C. There are indications that the mutation may have occurred in a regulatory gene, puvR, and as a result the operon, including a putative puvA gene (the structural gene for the synthesis of the 55-kdal protein), is expressed constitutively. A model for the control of the PUV operon is proposed.

Effect of triturated dilutions of ethanol on the peristaltic contractions of isolated rabbit intestine

Effect of triturated dilutions of ethanol from to 10(-3) to 10(-24) were studied on the peristaltic contractions of isolated rabbit intestinal pieces. Triturated dilutions of ethanol were applied in two doses. It was generally observed that the addition of first dose was followed by a small increase of 1.1 gms. in the resting tension which occurred at a slower rate in about 36.5 sec. The second doses however, increased the resting tension by 24 gms, in about 21 sec. In addition, the active tensions showed large variations on the application of first doses of triturated ethanol, while the second doses always decreased this parameter below the first dose levels. The rate of contractions was however, unaltered by both the first and second doses of ethanol, although an increase in the contraction times was found to be balanced by a simultaneous decrease either in the peak duration or relaxation times. The results are discussed in terms of electrophysiological, active state and free ionic Ca++ release phenomena.

A comparative study of the effects of ethanol, acetylcholine and adrenaline on various parameters of intestinal contractions of rabbit

A comparative study was carried out to observe the effects of ethanol, acetylcholine and adrenaline on various parameters of the contraction cycle of rabbit intestine. Acetylcholine and adrenaline were used in concentrations of 10(-3), either alone or in combination with absolute ethanol. The results showed that ethanol and acetylcholine had no effect on the rate of intestinal contractions while adrenaline increased it significantly. However, all these drugs decreased the active tension of the contracting intestine, the decrease being minimum for ethanol, moderate for acetylcholine and maximum for adrenaline. On the contrary, a small transient decrease in resting tension was produced by ethanol and this occurred at a very fast rate while adrenaline produced a marked decrease in this parameter, its rate being 6-10 times slower. Ethanol and acetylcholine were also found to increase the resting tension, it being 2 times greater and occurring at a faster rate with acetylcholine. It is suggested that these drugs produce their effect by altering resting membrane potential, Ca++ and other ion fluxes.

Effect of diet on transaminase and arginase activities

The composition of the diet greatly influences the enzyme activities of the liver. The effect of low carbohydrate diet on AST, ALT and arginase activities in liver and serum of rats was determined in the present study. Liver ALT and serum AST were significantly increased in animals fed on low carbohydrate diet, the activities of other enzymes remained unchanged.

Inducible DNA polymerase I synthesis in a UV hyper-resistant mutant of Escherichia coli

A mutant of Escherichia coli which is more resistant to shortwave UV light than its wild-type parent strain and which can synthesise DNA polymerase I constitutively has been further analysed. It carries two mutational alleles which are located about 1.5 min apart and cotransducible by P1 with the argH locus. The two mutational alleles have been segregated and their analysis shows that one of them is responsible for UV hyper-resistance whereas the other mutation confers UV sensitivity. Recombinant plasmids carrying various sections of the polA regulatory region, linked to a galK gene, were introduced into the mutant strains. Analysis of galactokinase shows that the enzyme activity in the UV hyper-resistant mutant is increased. The results suggest that the synthesis of DNA polymerase I in E. coli is inducible.

The isolation and characterization of bacteriophages infecting obligately thermophilic strains of Bacillus

Twenty-four thermophilic bacteriophages have been isolated from diverse sources such as compost, soil, silage and rotting straw. Although considerable individual host specificity was observed, the phages were able to infect most of the major taxonomic groups of Bacillus thermophiles. The phages varied considerably in morphology and size; the phage heads were either cylindrical or polyhedral with tails varying in length between 15 and 500 nm. Most of the phages were stable at 50 degrees C for 4-5 h but at 70 degrees C the plaque-forming units decreased by between 10(2)- and 10(7)-fold in 2 h. The DNA of morphologically similar phages was examined by restriction enzyme analysis, and some differences in the DNA fragment patterns were found. Efficiency of plating data indicated that 'B. caldotenax' has a restriction and modification system. These phages may be valuable for the study of the genetics of thermophilic bacilli: transduction of 'B. caldotenax' and 'B. caldovelox' by phage JS017 has been observed.

Isolation and analysis of a mutant of Escherichia coli hyper-resistant to near-ultraviolet light plus 8-methoxypsoralen

A mutant of Escherichia coli K12 was isolated which shows enhanced resistance towards near-ultraviolet (NUV) light plus 8-methoxypsoralen (MPS) compared with its wild-type parent strain. The PUVA (NUV + MPS)-resistant strain remains as sensitive for far-ultraviolet (FUV) light as its parent strain. A recA- derivative of this mutant strain was as sensitive to PUVA as its reca- parental strain. A polyacrylamide gel electrophoresis study of total cell lysates from the mutant bacteria showed that a protein of approximately 55 kd was synthesised in higher concentrations compared with its synthesis in the wild-type parent strain. Furthermore, synthesis of this protein was reduced in the recA- derivative of the mutant strain suggesting that the recA gene product might be acting as a regulator of the synthesis of the 55-kd protein. It is suggested that in E. coli damage to DNA by PUVA can be repaired by a specific RecA LexA-inducible repair system and the repair efficiency is enhanced if the 55-kd protein is present in concentrations higher than that synthesised by the wild-type parent E. coli.

Studies on cataractogenesis in humans and in rats with alloxan-induced diabetes. I. Cation transport and sodium-potassium-dependent ATPase

Changes in the cation balance cause hydration and initiate the process of lens opacification. Such alterations were studied in human cataractous lenses and during the development of alloxan-induced diabetic cataract in rats by biochemical and histochemical techniques. The development of alloxan-induced cataract in rats was examined in vivo which showed cortical opacities beginning after 32 days. These opacities did progress to maturity after 64 days and finally the lenses were completely opacified after 96 days of alloxan treatment. The histochemical localization of sodium-potassium-activated adenosine triphosphatase using three different methods provided information on the possible role of this enzyme in normal and cataractous lenses. In human cataractous lenses, sodium-potassium adenosine triphosphatase activity was found to be considerably decreased, whereas no activity of this enzyme was localized in human diabetic cataractous lenses. An animal model provided evidence that an apparent decrease of sodium-potassium adenosine triphosphatase may be involved in the initiation of alloxan-induced diabetic cataract in rats.

Studies on cataractogenesis in humans and in rats with alloxan-induced diabetes. II. Histochemical evaluation of lenticular enzymes

The effect of cataractogenesis on the behavior of some enzymes involved in glucose metabolism was examined histochemically both in human lenses and in rat lenses from rats with alloxan-induced diabetes. Several modifications in the currently available techniques were made in order to localize glucose-6-phosphate dehydrogenase, aldose reductase, sorbitol dehydrogenase, hexokinase and ketohexokinase in ocular lens. Human cataractous lenses showed a precipitous drop in glucose-6-phosphate dehydrogenase activity, whereas the lenticular tissues of alloxan-treated rats showed a gradual decrease of this enzyme with the prolongation of diabetes. Aldose reductase activity increased in hypermature and senile diabetic cataracts, whereas sorbitol dehydrogenase activity decreased in these lenses. Similarly, in alloxan-diabetic rat lenses the activity of aldose reductase increased while that of sorbitol dehydrogenase decreased with the prolongation of diabetes. Attempts were made to localize hexokinase and ketohexokinase in ocular lens.

Partial purification and characterization of lenticular S-adenosylmethionine synthetase

Lenticular S-adenosylmethionine synthetase has been partially purified and characterized. Lower levels of S-adenosylmethionine synthetase were detected by a sensitive radioactive assay procedure in the lenticular extract obtained from the pooled lenses of alloxan-treated rats 96 days of age as compared to the nontreated controls. With respect to chromatographic behavior and kinetic analysis, lenticular S-adenosylmethionine synthetase closely resembled that of the corresponding liver enzyme.

Regulation of the synthesis of nucleoside catabolic enzymes in Escherichia coli: further analysis of a deo Oc mutant strain

Four genes, deoA, deoB, deoC, and deoD, involved in the synthesis of nucleoside and deoxynucleoside catabolic enzymes, are located contiguously in the order C-A-B-D on the linkage map of E. coli. They constitute two overlapping operons, one transcribing all the four genes and the other deoB and deoD. To the left of deoC are located two promoter-operator regions in the order deoPO-cytPO. They are involved in controlling the expression of the tetracistronic mRNA. For efficient binding of RNA polymerase at the cytPO site the cAMP+CRP complex is required, whereas binding of RNA polymerase at the deoPO site is independent of this complex. Evidence is available for the existence of yet another controlling site, PO-3, located between deoA and deoB; this controls the expression of deoB and deoD. Both the operons are transcribed in a clockwise direction. An operator constitutive (Oc) type mutant affecting the synthesis of all four deo enzymes has been analysed. Because of this mutation the strain has become insensitive to catabolite repression. The results confirm the order of the gene in the controlling region to be deoPO-cytPO and the mutation, previously analysed as a deletion, appears to have deleted cytPO deoC region of the chromosome.

Isolation and characterization of a mutant of Escherichia coli K12 synthesizing DNA polymerase I and endonuclease I constitutively

A mutant of Escherichia coli K12, highly resistant to ultraviolet radiation, has been isolated. Preliminary tests show that this mutant is also resistant to mitomycin C, nalidixic acid, fluorouracil and thymineless death. The mutant strain apparently repairs its damaged DNA more efficiently than wild-type E. coli K12 strains and, to do so, constitutively produces 35 times more DNA polymerase I and 12 times more endonuclease I than the wild-type strain.

Thymineless death in recombination deficient mutants of Escherichia coli K12

When grown in thymine-free minimal synthetic medium, thyA recA mutants of Escherichia coli K12 were comparatively more resistant and thyA recBC mutants more sensitive to thymineless death (TLD) than their respective parent strains. No excessive numbers of single-strand breaks were observed in the DNA of the recBC mutant strain starved for thymine, hence the hypersensitivity for TLD in this strain was not caused by this type of DNA damage. Although experiments were performed with the same recBC mutant strain as used by earlier workers, results presented here contradict earlier findings that recBC mutants are no more sensitive and recA mutants are no more resistant to TLD.

Thymidine sensitivity of certain strains of Escherichia coli K12

In studies on thymineless death in Escherichia coli K12, it was noted that certain thymine requiring mutants were inhibited by thymidine. The pattern of inhibition varied with the conditions and media employed. Accumulation of deoxyribose-5-phosphate as a possible reason for inhibition is ruled out since the strains are deoB- (formerly drm-) and synthesize deoxyriboaldolase constitutively. We report this inhibition to alert investigators who study thymidine metabolism or use thymidine to label the DNA.