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R Samuel

Publications and source records attributed to R Samuel.

At least 19 recordsLinked to original sources
PubMed2001

Stress distribution around maxillary implants in anatomic photoelastic models of varying geometry. Part I.

STATEMENT OF PROBLEM: It is unclear which implant inclination and position are most favorable in relation to the supporting anatomy and loading direction in the maxilla. PURPOSE: This study was designed to examine stress distribution around implants in a 2-dimensional photoelastic anatomic model. MATERIAL AND METHODS: Two 2-dimensional photoelastic models were prepared with opposing 8-degree cylinder metal implant and molar teeth analogues. A frontal anatomic sectional plate model based on a CT section at the first molar was symmetrically loaded through its long axis. A midfacial rectangular model based on the same section was loaded in a different direction with varying supporting geometries. RESULTS: Stress distribution around the maxillary implant was highest in the buccal concavity at the apical buccal third and in the lingual concavity on intercuspal loading. No stress concentration occurred at the implant apex under the sinus for axial and nonaxial loading in both anatomic model geometries. On lateral loading, stress concentration was observed at the buccal concavity and at the implant neck. In the midfacial block model, principal stresses were concentrated at the maxillary implant neck on nonaxial loading and at the apex on axial loading. CONCLUSION: This 2-dimensional skull model showed different patterns of stress distribution among the maxillary implant, mandibular implant, and teeth. The highest principal stress concentration was seen at the buccal concavity of the maxillary implant; this may play a role in osseointegration with highly angled implants in the posterior maxilla. Differences in stress distribution between anatomic and nonanatomic models showed how the supporting geometry (for example, sinus/nasal anatomy), boundary conditions, and loading direction influence stress distribution.

Birefringence↗
PubMed2001

Phylogenetic analysis of phagotrophic, photomorphic and osmotrophic euglenoids by using the nuclear 18S rDNA sequence.

Phylogenetic analyses of 35 strains including 25 previously published sequences and 10 which have been newly sequenced, representing two species of Euglena, five species of Phacus and three species of Astasia, were carried out using the SSU rDNA. Parsimony, distance and maximum-likelihood inferred phylogenies support (1) monophyly of the euglenoids, (2) kinetoplastids as the sister group, (3) the phagotrophic Petalomonas cantuscygni Cann et Pennick anchoring the base of the euglenoid lineage, (4) evolution of phototrophy within the euglenoids from a single event, (5) multiple origins of osmotrophic euglenoids and (6) polyphyly of the genera Euglena Ehrenberg and Phacus Dujardin. Analyses also indicate that Lepocinclis Perty, Trachelomonas Ehrenberg and Astasia Dujardin are polyphyletic. In addition, the results suggest that neither the Euglenales nor the Eutreptiales form a monophyletic lineage, thus questioning currently available classifications. Concerning the phagotrophic mode of nutrition, the data suggest that the feeding apparatus arose multiple times.

Animals↗
PubMed2000

Antiretroviral therapy 2000.

As we enter the new millennium, there have been dramatic improvements in the care of patients with HIV infection. These have prolonged life and decreased morbidity and mortality. There are fourteen currently available antiretrovirals approved in the United States for the treatment of this infection. The medications, including their pharmacokinetic properties, side effects, and dosing are reviewed. In addition, the current approach to the use of these medicines is discussed.

Anti-HIV Agents↗
PubMed2000

Herd immunity and herd effect: new insights and definitions.

The term herd immunity has been used by various authors to conform to different definitions. Earlier this situation had been identified but not corrected. We propose that it should have precise meaning for which purpose a new definition is offered: "the proportion of subjects with immunity in a given population". This definition dissociates herd immunity from the indirect protection observed in the unimmunised segment of a population in which a large proportion is immunised, for which the term 'herd effect' is proposed. It is defined as: "the reduction of infection or disease in the unimmunised segment as a result of immunising a proportion of the population". Herd immunity can be measured by testing a sample of the population for the presence of the chosen immune parameter. Herd effect can be measured by quantifying the decline in incidence in the unimmunised segment of a population in which an immunisation programme is instituted. Herd immunity applies to immunisation or infection, human to human transmitted or otherwise. On the other hand, herd effect applies to immunisation or other health interventions which reduce the probability of transmission, confined to infections transmitted human to human, directly or via vector. The induced herd immunity of a given vaccine exhibits geographic variation as it depends upon coverage and efficacy of the vaccine, both of which can vary geographically. Herd effect is determined by herd immunity as well as the force of transmission of the corresponding infection. Clear understanding of these phenomena and their relationships will help improve the design of effective and efficient immunisation programmes aimed at control, elimination or eradication of vaccine preventable infectious diseases.

Adult↗
PubMed2000

DOT or not? Direct observation of anti-tuberculosis treatment and patient outcomes, Kerala State, India.

SETTING: The Pathanamthittha District of Kerala State, India, where the directly observed treatment, short-course (DOTS) programme was started in October 1994. OBJECTIVE: To determine the frequency with which direct observation actually occurred within a district-level DOTS programme, and the association of treatment observation with treatment outcome under programme conditions. DESIGN: This retrospective study included 200 consecutive, newly-detected, smear-positive patients registered under the project between February 1995 and February 1996 at the District Tuberculosis Centre, as well as health workers responsible for providing directly observed treatment (DOT) who were separately and confidentially interviewed. Treatment outcomes were identified from results of sputum smear examinations for acid-fast bacilli. RESULTS: Although all patients were recorded as having received DOT, more than a quarter of patients (26.5%) did not actually receive it. The 53 patients who were not directly observed were much more likely to have treatment failure or relapse, as compared to those who had received DOT (45% vs 3%, relative risk 16.6, 95% confidence intervals 6-46, P < 0.001). Women were somewhat less likely than men (61% vs 76%, P = 0.06) to receive DOT. Non-receivers of DOT accounted for 86% (24/28) of treatment failures or relapses. CONCLUSION: Patients treated without direct observation have a substantially higher risk of adverse outcome than those treated under direct observation. To be maximally effective, the DOTS programme must be both confidential and convenient.

Adult↗
PubMed1999

Always be prepared

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Journal Article↗
PubMed1999

Detection of rubella virus-specific immunoglobulin G in saliva by an amplification-based enzyme-linked immunosorbent assay using monoclonal antibody to fluorescein isothiocyanate.

An immunoglobulin G (IgG)-capture enzyme-linked immunosorbent assay (ELISA) for rubella virus is described. The assay uses a fluorescein isothiocyanate (FITC)-anti-FITC amplification system. The detection limit of the ELISA was approximately 7 IU of rubella virus-specific IgG per ml of serum sample. For saliva samples the performances of the capture ELISA and previously described radioimmunoassay were assessed, and the results of those two assays were compared to the rubella virus-specific IgG result obtained by a commercial ELISA (Behring Enzygnost) with a panel of paired serum and saliva samples. This comparison showed that the capture ELISA with saliva was more sensitive than the radioimmunoassay and that the results correlated better with the serum IgG result than the results of the radioimmunoassay did, with an overall sensitivity of 82% and a rank correlation of 0.68, whereas the sensitivity and rank correlation for the radioimmunoassay were 74% and 0.45, respectively. For subjects of 10 years of age or younger, the ELISA with saliva had a sensitivity of 94% and a specificity of 100% compared to the results of the ELISA (Behring Enzygnost) for rubella virus-specific IgG with corresponding serum samples. The sensitivity was much lower for subjects ages 17 years or older. The assay may have wider epidemiological use with saliva specimens, particularly those from children.

Adolescent↗
PubMed1998

Disease surveillance at district level: a model for developing countries.

For over a decade we have maintained within a district of 5 million people, a system of prompt reporting of cases of childhood vaccine-preventable diseases, encephalitis, meningitis, hepatitis, and rabies; together with a sentinel laboratory surveillance of cholera, typhoid fever, malaria, HIV infection and antimicrobial-resistance patterns of selected pathogens. The system combined government and private sectors, with every hospital enrolled and participating. Reports were scanned daily on a computer for any clustering of cases. Interventions included investigations, immunisation, antimicrobial treatment, health education, and physical rehabilitation of children with paralysis. All vaccine-preventable diseases have declined markedly, whilst malaria and HIV infections have increased steadily. Annual expense was less than one US cent per head. The reasons for the success and sustainability of this model include simplicity or reporting procedure, low budget, private-sector participation, personal rapport with people in the network, regular feedback of information through a monthly bulletin, and the visible interventions consequent upon reporting. This district-level disease surveillance model is replicable in developing countries for evaluating polio eradication efforts, monitoring immunisation programmes, detecting outbreaks of old or new diseases, and for evaluating control measures.

Adult↗
PubMed1997

Control of rubella and congenital rubella syndrome (CRS) in developing countries, Part 1: Burden of disease from CRS.

Congenital rubella syndrome (CRS) can lead to deafness, heart disease, and cataracts, and a variety of other permanent manifestations. In developing countries, the burden of CRS has been assessed as follows: by surveillance of CRS; by surveillance of acquired rubella; by age-stratified serosurveys; and by serosurveys documenting the rubella susceptibility of women of childbearing age. During rubella outbreaks, rates of CRS per 1000 live births were at least 1.7 in Israel, 1.7 in Jamaica, 0.7 in Oman, 2.2 in Panama, 1.5 in Singapore, 0.9 in Sri Lanka, and 0.6 in Trinidad and Tobago. These rates are similar to those reported from industrialized countries during the pre-vaccine era. Special studies of CRS have been reported from all WHO regions. Rubella surveillance data show that epidemics occur every 4-7 years, similar to the situation in Europe during the pre-vaccination era. In developing countries, the estimated average age at infection varies from 2-3 years to 8 years. For 45 developing countries we identified serosurveys of women of childbearing age that had enrolled > or = 100 individuals. The proportion of women who remained susceptible to rubella (e.g. seronegative) was < 10% in 13 countries. 10-24% in 20 countries, and > or = 25% in 12 countries. Discussed are methods to improve the surveillance of rubella and CRS in developing countries.

Adolescent↗
PubMed1997

Control of rubella and congenital rubella syndrome (CRS) in developing countries, Part 2: Vaccination against rubella.

In 1995-96 we conducted a review of rubella immunization strategies. Worldwide, 78 countries (more than one-third) reported a national policy of using rubella vaccine. This was closely related to country economic status. Based on the United Nations country classification, rubella vaccine is used in 92% of industrialized countries, 36% of those with economies-in-transition, and 28% of developing countries. Cases of congenital rubella syndrome (CRS) may be prevented as follows: by providing direct protection to women and/or schoolgirls (a selective vaccination strategy); by vaccinating boys and girls to provide indirect protection by reducing the transmission of rubella virus (a childhood vaccination strategy); or by a combination of these approaches (a combined strategy). A combined strategy was most commonly reported (60% of countries); seven countries (9%) reported a selective strategy; and 24 countries (31%) reported only childhood immunization. Experience has shown that it is essential to include vaccination of women of childbearing age in any rubella control strategy. Childhood vaccination alone may pose a risk of an increase in CRS cases. Although many countries have introduced rubella vaccine, few report any data on the impact of vaccination. Countries using rubella vaccine need to establish surveillance for rubella and CRS and monitor coverage in each of the target groups.

Adolescent↗
PubMed1996

Assessment of children with the overt aggression scale.

Aggressive behavior is difficult to capture with most available rating instruments because it occurs with low frequency. The Overt Aggression Scale (OAS) was designed to capture all incidents on a 24-hour basis. To assess its usefulness, the OAS was piloted on 16 hospitalized, severely aggressive children with conduct disorder. OAS ratings capture episodes of aggressive behavior, measure trends in aggressive behavior over time, and appear to reflect change associated with pharmacotherapy in hospitalized children. This study suggests that the use of the OAS on a children's psychiatric inpatient unit is appropriate and feasible for clinical as well as research purposes.

Aggression↗
PubMed1994

Hypoparathyroidism--a long-term follow-up experience with 1 alpha-vitamin D3 therapy.

OBJECTIVE: Previous studies have suggested that alpha-D3 therapy can cause deterioration in renal function. We have, therefore, examined the long-term effect of 1 alpha-hydroxyvitamin D3 (alpha-D3) administration upon renal function in hypoparathyroid patients. DESIGN: This is a prospective long-term follow-up study of alpha-D3 administration on hypoparathyroid patients at a mean daily dose of 1 microgram (range 0.5-2.5 micrograms) during a total of 2040 patient-months. PATIENTS: Seventeen unselected patients (14 females and 3 males), two with primary and 15 with post-surgical hypoparathyroidism. RESULTS: The significant effect of alpha-D3 on serum and urinary calcium was achieved during the first week of treatment and remained stable at the same range during the close follow-up of 2040 patient-months. No significant change was observed in the serum creatinine during the whole follow-up period. During follow-up, five women developed hypercalciuria and one patient developed hypercalcaemia that disappeared when the dose of the drug was reduced or discontinued. CONCLUSIONS: From our study we concluded that alpha-D3 is a safe and effective drug in the long-term therapy of hypoparathyroid patients.

Adolescent↗
PubMed1994

Aminohydroxy propylidene bisphosphonate (APD) treatment improves the clinical skeletal manifestations of Gaucher's disease.

OBJECTIVE: To evaluate the long-term effects and safety of aminohydroxy propylidene bisphosphonate (APD) treatment on the frequency and severity of the clinical skeletal manifestations of Gaucher's disease. METHODOLOGY: Five adolescents who suffered from recurrent bone crisis episodes and atraumatic bone fractures due to Gaucher's disease were treated with APD for 14 to 83 months. RESULTS: During the 6 years before treatment, the patients suffered from 6 to 17 bone crisis episodes, or 1 to 2.8 episodes per patient per year. Three patients were free from bone crisis episodes during 14 to 32 months of ADP treatment, while two patients had two such episodes during 60 and 83 months of APD treatment (these represent a decrease in bone crisis episodes from 1 and 2.8 per year to 0.4 and 0.3 per year, respectively). Although four patients suffered from 1 to 3 atraumatic bone fractures during the 6 years preceding treatment (a total of 10 fractures), only one patient sustained a fracture on APD treatment (total of 219 months of treatment). Using APD was not associated with clinical side effects, biochemical aberrations, significant changes in liver and kidney function, or changes in serum levels of the hormones regulating mineral metabolism. In all patients, a band-like metaphyseal sclerosis appeared on radiography of the long bone. However, APD did not interfere with bone growth. CONCLUSIONS: The marked clinical improvement in the clinical skeletal manifestations of Gaucher's disease and the absence of toxic side effects in adolescent patients treated with APD support previous findings in three adult patients on the efficacy of APD and indicate possibilities for its use in inducing prolonged remissions in affected patients.

Adolescent↗
PubMed1993

Factors affecting immunization coverage levels in a district of India.

Immunization coverage is measured to assess the performance of the Expanded Programme on Immunization. In 1988 we conducted a coverage survey among 12-23 month-old children in the North Arcot District (population 5,007,746) in southern India. In each of the 12 towns a 30-cluster sample survey was conducted. In the 35 rural blocks with 1590 panchayats, 159 were selected systematically and all children (n = 7300) were surveyed. In the towns, coverage ranged for measles vaccine from 29 to 53%, BCG from 65 to 91% and OPV and DPT third dose from just over 60% to just over 80%. In the rural areas, coverage ranged for measles vaccine from 10.8 to 19.3%, BCG 25.1-34.1%, DPT third dose 42.2-50.4% and OPV third dose 39.6-48%. In the towns, 25, 66, 67 and 59% of BCG, DPT, OPV and measles vaccines had been provided by private agencies showing that availability of vaccines throughout the week and easy access even in payment terms played an important role in achieving higher levels of coverage compared with rural areas where all vaccines are given by Government agencies, free of charge. In the rural areas, significantly large variations in coverage were seen among panchayats--large and peri-urban panchayats had significantly better coverage than small and more rural panchayats. Within any given block (the population unit consisting of 30-40 panchayats served by a Primary Health Centre), there were large variations in the levels of immunization coverage between panchayats.(ABSTRACT TRUNCATED AT 250 WORDS)

BCG Vaccine↗