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Biomedical subjects

J R Allen

Publications and source records attributed to J R Allen.

At least 73 records · Page 4Linked to original sources
PubMed1993

Development of a paediatric indirect calorimeter.

An indirect calorimeter was developed to measure resting energy expenditure (REE) and respiratory quotient (RQ) in a clinical paediatric population. The design is suitable for any child spontaneously breathing room air. Measurements are possible from small babies to large hypermetabolic adolescents due to the ability to set and control flow from the patient headbox across the range 2-40 l/min. The calorimeter is mobile, it is electrically safe and the patient interface may be disinfected. An alcohol burning technique, that can emulate a clinical test for children of various sizes, is used to check the system, which has a high level of accuracy across a range of conditions. The indirect calorimeter has been successfully used to measure a large number of children of different sizes.

Adolescent↗
PubMed1992

Coding assignments of the genome of adult diarrhea rotavirus.

Adult diarrhea rotavirus (ADRV) has caused epidemics of diarrhea in China since 1982 and remains the only group B rotavirus associated with widespread disease in humans. We recently characterized the proteins of ADRV and have now proceeded to identify the gene segments encoding each protein. Viral RNA transcripts were synthesized in vitro with the endogenous viral RNA polymerase and separated by electrophoresis in agarose. The individual transcripts were translated in a cell-free system using nuclease-treated rabbit reticulocyte lysates. The translation products were compared with polypeptides found in purified virus and were characterized by SDS-PAGE, immunoprecipitation, and Western blot analysis using antisera to double- and single-shelled virions, virus cores, and monoclonal antibodies. Furthermore, individual RNA transcripts were hybridized to total dsRNA to determine their genomic origin. Based on this analysis, the core polypeptides VP1, VP2 and VP3 are encoded by segments 1, 2, and 3, respectively. The main polypeptides in the inner capsid, VP6, and the outer capsid, VP4 and VP7, are encoded by segments 6, 4, and 8 respectively. Segments 5, 7, and 9 code for 60, 45, and 30 kDa nonstructural polypeptides. Two other nonstructural polypeptides (24 and 25 kDa) are derived from gene segment 11. Gene segment 10 codes for a 26 kDa polypeptide that is precipitated with serum to ADRV and may be a structural protein VP9. With this exception, gene coding assignments of ADRV are comparable to those of the group A rotaviruses. Our results have clear implications for further work in cloning, sequencing, and expression genes of ADRV and can provide direction towards understanding the origin and the evolution of this virus.

Animals↗
PubMed1992

Outbreaks of summer rotavirus linked to laboratory practices. The National Rotavirus Surveillance System.

In temperate regions rotavirus diarrhea is a disease of the cooler months of the year, but little is known about its patterns in the summer. We report on the first year of national surveillance of rotavirus, during which we actively investigated patterns of summer activity. We obtained data on rotavirus testing from 85 laboratories in 48 states, conducted a survey of their testing practices and retested for confirmation positive specimens from laboratories reporting high rates of positivity during the summer. During 1989 participating laboratories reported 4011 specimens tested for rotavirus during July and August, of which 436 (11%) were said to be positive. Most laboratories reported low rates of positivity during these months (median percent positive, 3), but five had very high rates of summer positivity (> 30%). These five laboratories were geographically separated, and neighboring laboratories showed little rotavirus activity. Positive specimens submitted by four of these centers with high rates of summer rotavirus could not be confirmed. A survey of laboratory methods found one commercial assay (TestPack) and two laboratory practices (failure to use controls and involvement of more than six technicians in the testing process) to be associated with high rates of summer positivity. Moderate rates of positivity (11 to 30%) were fond frequently in the southwest during July and August; reference testing of specimens from these laboratories confirmed positivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Laboratory Techniques↗
PubMed1992

Identification of cognate genes among heterologous strains of group B rotavirus.

The genetic relatedness of group B rotavirus (GBR) strains has previously been documented by hybridization with probes derived from whole genomic sequences, but the relationship of individual genes of heterologous GBR strains has not been evaluated. Definition of cognate GBR genes would facilitate investigation of the determinants of group specificity, serotype identity, and neutralization epitopes. Therefore, we investigated the genetic relatedness of three GBR strains by means of Northern (RNA) blot hybridization with isotopically labeled probes prepared from each of the 11 genes of the IDIR strain of GBR. Under low-stringency conditions, hybridization between each of the IDIR gene probes and genomic RNA from the ADRV strain of GBR was observed. Genomic RNA obtained from a bovine strain of GBR hybridized with 9 of the 11 IDIR gene probes. In most cases, cognate genes of each of the GBR strains appeared to migrate to similar positions following polyacrylamide gel electrophoresis. However, the electropherotype positions of GBR genes 5, 6, and 7 were different for each of the three GBR strains. Identification of these genomic segments among GBR strains should prove helpful in future evaluations of GBR structure and function.

Animals↗
PubMed1991

The costs and benefits of bone marrow transplantation.

The average direct costs of performing a bone marrow transplant (BMT), including the subsequent year, was found to be NZ$27,074 for 43 consecutive transplants. In 29 BMTs a full two year period of follow up was available and a quality of life analysis was carried out on these patients. It was calculated that 59 quality adjusted life years (QALYs) had been gained by the BMT procedure at the time of analysis. By combining these two analyses the cost of each QALY gained by BMT is NZ$13,272. The relatively low cost of BMT is partly due to the extremely low annual costs in second and subsequent years post BMT. In our patients this cost amounted to $195 per year. The costs and benefits of BMT compare very favourably with other complex medical procedures.

Adult↗
PubMed1991

The efficiency of intestinal calcium absorption is increased in late pregnancy but not in established lactation.

The fractional absorption of calcium (FA-Ca) was measured using a dual non-radioactive Ca isotope technique in 26 control women, 49 women in the last trimester (36 weeks) of pregnancy and 31 of these women in established (20 weeks) lactation. The ratio of the two non-radioactive Ca isotopes was measured, by high precision thermal ionisation mass spectrometry, in urine 12-24 hours after administration and was used to calculate FA-Ca. This is the first study to clearly show that FA-Ca is significantly elevated in late pregnancy but not in established lactation, when compared with control women.

Calcium↗
PubMed1991

Tick resistance in mast cell-deficient mice: histological studies.

Mast cell-deficient W/Wv mice and their mast cell-sufficient +/+ genetic controls were allowed to undergo three successive infestations with Dermacentor variabilis larvae. Histological examination of the skin of infected mice revealed large dermal accumulations of eosinophils and smaller numbers of neutrophils. The numbers of both eosinophils and neutrophils increased significantly in W/Wv and +/+ mice during secondary and tertiary infestations. Mast cell numbers were also found to increase in the skin of +/+ mice during tertiary infestations. Resistance, as measured by decreased larval engorged weights on day 5 of each infestation, was acquired by both strains of mice.

Animals↗
PubMed1991

Astrovirus and adenovirus associated with diarrhea in children in day care settings.

The relative importance of astrovirus and adenoviruses as etiologic agents of diarrhea among children in day care was examined. Stool specimens from this prospective study were screened for both astrovirus and adenovirus hexon with two new indirect double-antibody assays and for enteric adenoviruses with an EIA specific for serotypes 40 and 41. Astrovirus was detected in a significantly greater percentage of children with diarrhea (4%, 21/524) than of those without (less than 1%, 1/138) (P less than .05); however, no difference between such such children with adenovirus infections was found (8%, 43/565, and 8%, 10/129, respectively). Overall, 30% (13/43) of all adenovirus hexon-positive specimens were enteric serotypes, and by extrapolation, enteric adenoviruses were identified in an equal percentage of children (2%) with and without diarrhea. This study documents the presence of astrovirus and enteric adenoviruses among children in day care in the United States, associates astrovirus with diarrhea in this setting, and suggests that viral agents may be the most common enteric pathogens among children with diarrhea in day care.

Adenovirus Infections, Human↗
PubMed1991

Detection of astrovirus in pediatric stool samples by immunoassay and RNA probe.

Two new astrovirus assays, a rapid biotin-avidin enzyme immunoassay (EIA) and RNA probe hybridization, were developed and compared with an established astrovirus assay, an indirect EIA, and immune electron microscopy. Sensitivity and specificity were evaluated by using a screening panel of 22 astrovirus-positive and 305 astrovirus-negative fecal specimens. The biotin-avidin assay was equivalent in performance to the reference indirect assay, and both could detect about 10 ng of viral protein. Although the probe was more sensitive than either EIA and could detect higher dilutions of virus in tissue culture and stool specimens, it did not detect more astrovirus-positive fecal specimens. Of the 22 astrovirus-positive specimens detected by the EIAs, 20 were confirmed by immune electron microscopy with hyperimmune rabbit antiserum. To determine the usefulness of EIAs for large epidemiologic studies, EIAs were used to screen 1,289 stool specimens from three studies of children with and without diarrhea. Astrovirus was detected in 3.5% of specimens from children with diarrhea and 1.9% of specimens from those without diarrhea. Our results indicate that the biotin-avidin EIA is an efficient, sensitive, and specific method for routinely screening large numbers of fecal samples and that its application in epidemiologic studies may yield higher rates of astrovirus infection than have been found previously by other methods.

Avidin↗
PubMed1991

Detection of group B and C rotaviruses by polymerase chain reaction.

We adapted the polymerase chain reaction (PCR) to detect the noncultivatable group B and C rotaviruses and introduced a simple and convenient technique to purify viral RNA from stool specimens. Double-stranded RNA present in stool extracts was purified by adsorption to hydroxyapatite and was used as the template for reverse transcription and polymerase amplification. Primer pairs specific for group B (gene 8) and group C (gene 6) rotaviruses were selected to amplify group-characteristic sizes of cDNA copies readily identifiable in ethidium bromide-stained agarose gels. These primer pairs were used separately in individual PCR assays or were pooled with a primer pair specific for group A rotavirus (gene 9) in a combined PCR assay for the simultaneous detection of all three rotavirus groups. The method was very sensitive and was used to identify both human and porcine strains of group B and C rotaviruses in stool specimens. A second PCR amplification with internal group-specific primers served to increase further the sensitivity of the test and to confirm the diagnostic results obtained in the first amplification.

Base Sequence↗
PubMed1991

Acute effects of an oral calcium load in pregnancy and lactation: findings on renal calcium conservation and biochemical indices of bone turnover.

An oral calcium (Ca) tolerance test was used to compare the acute calcaemic, calciuric, parathyroid and bone turnover responses in 21 women at 36 weeks of pregnancy, 27 breast-feeding women studied 22 weeks postpartum and 27 control women. In all groups the oral Ca load increased plasma Ca and urinary calcium excretion (CaE), reduced intact PTH concentration (and consequently reduced renal phosphate and cyclic AMP excretion) and reduced hydroxyproline excretion (HypE, a biochemical index of bone resorption). There were no changes in the biochemical indices of bone formation, serum osteocalcin (elevated in the lactating group) and alkaline phosphatase, in any group. The pregnant women had the same fall in HypE and a greater calcaemic response than the controls. These results suggest that there is increased intestinal Ca absorption efficiency and a normal rate of bone resorption in late pregnancy. In contrast, the lactating women had a greater fall in HypE (from a baseline twice that of controls) and a significantly lower (p less than 0.001) rise in CaE, despite a calcaemic response similar to that of controls. Therefore, in lactation there is increased bone turnover and an increased capacity to reabsorb Ca in the renal tubule, compared to controls. An oral calcium supplement may benefit breast-feeding women, by reducing lactation-related elevated rate of bone resorption and consequent loss of trabecular bone.

Absorption↗
PubMed1991

Primary pancreatic tuberculosis.

A 71-year-old man developed weight loss, nausea, and night sweats. A PPD skin test was positive; chest films were normal. Abdominal computerized tomography revealed a mass in the head of the pancreas. Laparotomy revealed a 3 cm by 5 cm multi-loculated abscess cavity. Cultures grew Mycobacterium tuberculum. The diagnostic criteria for abdominal tuberculosis include skin test positivity, localized disease, and culture verification. This is the first reported case that fulfills diagnostic criteria for primary pancreatic tuberculosis.

Aged↗
PubMed1991

Operative procedures not involving the heart after percutaneous transluminal coronary angioplasty.

The benefit of coronary artery bypass grafting (CABG) in patients with coronary artery disease (CAD) who require extensive surgical procedures not involving the heart has been established. During the past decade, percutaneous transluminal coronary angioplasty (PTCA) has been developed as an alternative therapy to CABG for patients with CAD. In an attempt to determine the safety of other surgical procedures after PTCA, we retrospectively reviewed 148 patients who underwent 193 surgical procedures from four to 1,867 days after PTCA for CAD. Seventy-two patients had surgical treatment within 90 days of PTCA. Thirty-five patients had CABG prior to PTCA, and 113 had PTCA as the initial treatment for CAD. Four patients died postoperatively, only one death was cardiac in origin. One patient had a myocardial infarction postoperatively (the one cardiac death). Fifteen patients had other cardiac complications (nine patients with arrhythmias and six with myocardial ischemia). Patients operated upon within 90 days of PTCA had no increased cardiac morbidity, although the one myocardial infarction occurred in this group. No difference in cardiac morbidity occurred in patients with multivessel CAD treated by PTCA compared with single vessel disease. However, patients more than 60 years of age had more cardiac problems (16 of 110) than those less than 60 years of age (zero of 38) (p = 0.01). Treatment of CAD by PTCA protects the myocardium from fatal cardiac events and myocardial infarction during subsequent noncardiac operative procedures even early (less than 90 days) in the post-PTCA period. Older patients seem to be at higher risk, however, for nonfatal cardiac complications.

Abdomen↗
PubMed1991

Factors V and VII anticoagulant activities in the salivary glands of feeding Dermacentor andersoni ticks.

The salivary glands of Dermacentor andersoni ticks possess anticoagulant activities that can alter the clotting time of rabbit whole blood. Salivary gland extracts from female ticks inhibit both the intrinsic and extrinsic coagulation systems, and maximal activities against both pathways occur when the ticks attain about 250 mg feeding weight. These anticoagulants are directed against both coagulation factors V and VII, but they do not affect factors II or X. Despite this salivary anticoagulant activity, heavily tick-infested rabbits suffer no visible alteration of their peripheral blood coagulability and have no detectable circulating fibrin degradation products, suggesting that the ticks do not secrete a factor with fibrinolytic activity.

Animals↗
PubMed1991

Nonspecific activation of complement factor 5 by isolated Dermacentor andersoni salivary antigens.

Salivary gland extracts from feeding Dermacentor andersoni ticks contain an activity that activated both rabbit and human complement to produce inflammatory cell chemotactic activity. Purified salivary antigens (SGA), isolated from the glands of female ticks with anti-saliva immunoglobulins from tick-resistant rabbits, also induced chemotactin generation. It has been demonstrated previously that the intradermal injection of such SGA into normal animals induces nonspecific inflammatory reactions that mimic the responses accompanying tick feeding on normal animals. The chemotactic activity generated in serum by SGA was mediated either directly or indirectly by C5, as it could be abrogated by antisera directed against C5 but not by anti-C3 sera. That the in vitro generation of C5 by tick salivary proteins has relevance to tick feeding is suggested by the fact that many of the host inflammatory responses elicited by ixodid tick feeding also are effects known to be elicited by C5.

Animals↗
PubMed1991

Intranasal amphotericin B reduces the frequency of invasive aspergillosis in neutropenic patients.

PURPOSE: To retrospectively study the prophylaxis of invasive aspergillosis in neutropenic patients and to relate the frequency of this fungal disease to any causal or modifying factors that could be identified. PATIENTS AND METHODS: Between 1977 and 1988, 130 patients underwent 158 intensive treatment episodes to control acute leukemia, lymphoma, and aplastic anemia, and the frequency of complicating aspergillus infection was determined. RESULTS: Proven invasive aspergillus infections occurred in 22 cases, 12 of which were fatal. Invasive aspergillosis was suspected in a further 16 cases and all these patients recovered with amphotericin B treatment. Colonization by Aspergillus in the absence of clinically significant infection was seen in 31 treatment episodes. Invasive aspergillosis involved mainly the upper and lower respiratory tract and skin. Control of the infection was closely related to the control of the underlying disease, with subsequent return of normal marrow function and resolution of neutropenia. The incidence of aspergillus infection has decreased dramatically since 1985, most probably due to the introduction of intranasal amphotericin B. This occurred despite the persistence of aspergillus spores in the hematology ward air during the 1986 to 1988 period. CONCLUSION: Intranasal aerosolized amphotericin B may protect against invasive aspergillosis, even when neutropenic patients are cared for in conventional wards without HEPA filtration.

Administration, Intranasal↗