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Biomedical subjects

R J Jackson

Publications and source records attributed to R J Jackson.

At least 73 records · Page 4Linked to original sources
PubMed1999

Maternal pesticide exposure from multiple sources and selected congenital anomalies.

We explored the relation between various potential sources of maternal periconceptional pregnancy exposures to pesticides and congenital anomalies in offspring. Data were derived from a case-control study of fetuses and liveborn infants with orofacial clefts, neural tube defects, conotruncal defects, or limb anomalies, among 1987-1989 California births and fetal deaths. We conducted telephone interviews with mothers of 662 (85% of eligible) orofacial cleft cases, 265 (84%) neural tube defect cases, 207 (87%) conotruncal defect cases, 165 (84%) limb cases, and 734 (78%) nonmalformed controls. The odds ratio (OR) estimates did not indicate increased risk for any of the studied anomaly groups among women whose self-reported occupational tasks were considered by an industrial hygienist likely to involve pesticide exposures. Paternal occupational exposure to pesticides, as reported by the mother, revealed elevated ORs for only two of the cleft phenotypes [OR = 1.7 [95% confidence interval (CI) = 0.9-3.4] for multiple cleft lip with/without cleft palate and OR = 1.6 [95% CI = 0.7-3.4] for multiple cleft palate]. Use of pesticide products for household gardening, by mothers or by professional applicators, was associated with ORs > or =1.5 for most of the studied anomalies. Use of pesticide products for the control of pests in or around homes was not associated with elevated risks for most of the studied anomalies, although women who reported that a professional applied pesticides to their homes had increased risks for neural tube defect-affected pregnancies [OR = 1.6 (95% CI = 1.1-2.5)] and limb anomalies [OR = 1.6 (95% CI = 1.0-2.7)]. Having a pet cat or dog and treating its fleas was not associated with increased anomaly risk. Women who reported living within 0.25 miles of an agricultural crop revealed increased risks for offspring with neural tube defects [OR = 1.5 (95%CI = 1.1-2.1)]. For many of the comparisons, data were sparse, resulting in imprecise effect estimation. Despite our investigating multiple sources of potential pesticide exposures, without more specific information on chemical and level of exposure, we could not adequately discriminate whether the observed effects are valid, whether biased exposure reporting contributed to the observed elevated risks, or whether nonspecific measurement of exposure was responsible for many of the observed estimated risks not being elevated.

Adult↗
PubMed1998

A prokaryotic-like mode of cytoplasmic eukaryotic ribosome binding to the initiation codon during internal translation initiation of hepatitis C and classical swine fever virus RNAs.

Initiation of translation of hepatitis C virus and classical swine fever virus mRNAs results from internal ribosomal entry. We reconstituted internal ribosomal entry in vitro from purified translation components and monitored assembly of 48S ribosomal preinitiation complexes by toe-printing. Ribosomal subunits (40S) formed stable binary complexes on both mRNAs. The complex structure of these RNAs determined the correct positioning of the initiation codon in the ribosomal "P" site in binary complexes. Ribosomal binding and positioning on these mRNAs did not require the initiation factors eIF3, eIF4A, eIF4B, and eIF4F and translation of these mRNAs was not inhibited by a trans-dominant eIF4A mutant. Addition of Met-tRNAiMet, eIF2, and GTP to these binary ribosomal complexes resulted in formation of 48S preinitiation complexes. The striking similarities between this eukaryotic initiation mechanism and the mechanism of translation initiation in prokaryotes are discussed.

Animals↗
PubMed1998

Trace metals in urine of United States residents: reference range concentrations.

We measured 13 metals in the urine of 496 United States residents to establish reference range concentrations using inductively coupled argon plasma mass spectrometry and Zeeman graphite furnace atomic absorption spectrometry. We frequently found 8 of these analytes at detectable concentrations in urine specimens: molybdenum (in 99.8%); lead (98.8%); tin (89%); thallium (77%); antimony (73.5%); manganese (73%); cesium (71%); tungsten (70%); and platinum (69.7%). The 95th percentile concentration for molybdenum was 168 micrograms/L; concentrations ranged up to 688 micrograms/L. Lead concentrations ranged up to 67 micrograms/L, and the 95th upper percentile was 6.4 micrograms/L. Tin had 95th upper percentile of 20.1 micrograms/L. Other analytes measured at detectable concentrations included barium (in 67% of the specimens); beryllium (67%); chromium (54%); thorium (44%); and cobalt (43%). In almost every case, the 95th upper percentiles of these analytes were less than 15 micrograms/L.

Adult↗
PubMed1998

Management of multiple intestinal atresias and perforation with intraluminal stenting.

Intraluminal stenting of the gastrointestinal (GI) tract in both multiple intestinal atresias and perforations was used in three patients. In the atresia patients (2), a piercing trocar was used to create continuity of the GI tract and as a guide to thread the intestine over the stent. All patients currently demonstrate normal growth and development on routine enteral feeds. None developed anastomotic leaks or strictures.

Humans↗
PubMed1998

Preventing childhood lead poisoning: the challenge of change.

Because of their rapid growth, immature biologic systems, and their developmental characteristics, children are uniquely vulnerable to exposure to environmental hazards. One of these is lead. Revised lead screening guidelines, published by the Centers for Disease Control and Prevention in Fall 1997, no longer advocate universal screening in some places. These guidelines will (1) require new policies from local public health agencies, (2) require new approaches for clinicians and managed care organizations, especially those with Medicaid-recipient enrollees, to conduct screening of children who may be at risk for exposure to lead, (3) offer new challenges for environmental follow-up to children identified with elevated lead levels, and (4) provide opportunities for collaboration between managed care and public health agencies.

Aftercare↗
PubMed1998

Minimally invasive surgery: the pediatric surgery experience.

BACKGROUND: Minimally invasive surgery (MIS) has become an important aspect of general surgery. The degree to which pediatric surgeons have incorporated MIS into their practice is not known. STUDY DESIGN: An MIS survey was sent to all members of the American Pediatric Surgical Association. Respondents were separated into two groups: nonperformers and performers of MIS. Performers were asked how they were trained in MIS and the total number and types of minimally invasive procedures they have performed. RESULTS: Eighty-two percent of surveyed pediatric surgeons perform MIS. Eighty-seven percent received some or all of their training in a postgraduate course. Two percent received their only training during their general surgery residency. Forty-seven percent of performers reported 50 or fewer total procedures. A wide variety of procedures were reported, but laparoscopic cholecystectomy (95%) was the procedure most frequently reported. Thoracoscopic procedures (71%) were also reported at high rates. CONCLUSIONS: Most pediatric surgeons in our survey perform MIS. The high rate of laparoscopic cholecystectomies reported suggests that the initial MIS experience of pediatric surgeons in our survey is similar to adult general surgeons. The frequency, however, of thoracic cases reported indicates that MIS techniques are being applied to all areas of pediatric surgery. The total minimally invasive procedure experience of our respondents also suggests that pediatric surgeons are early in their learning curve.

Adult↗
PubMed1998

The polypyrimidine tract binding protein (PTB) requirement for internal initiation of translation of cardiovirus RNAs is conditional rather than absolute.

Picornavirus RNAs are translated by an unusual mechanism of internal ribosome entry that requires a substantial segment of the viral 5'-untranslated region, generally known as the internal ribosome entry segment (IRES), and in some circumstances may require cellular trans-acting proteins, particularly polypyrimidine tract binding protein (PTB). It is shown here that for encephalomyocarditis virus (EMCV), the PTB dependence of IRES function in vitro is determined partly by the nature of the reporter cistron, and more especially by the size of an A-rich bulge in the IRES. With a wild-type EMCV IRES (which has a bulge of 6 As), translation is effectively independent of PTB provided the IRES is driving the synthesis of EMCV viral polyprotein. With an enlarged (7A) bulge and heterologous reporters, translation is highly dependent on PTB. Intermediate levels of PTB dependence are seen with a 7A bulge IRES driving viral polyprotein synthesis or a wild-type (6A) bulge IRES linked to a heterologous reporter. None of these parameters influenced the binding of PTB to the high-affinity site in the IRES. These results argue that PTB is not an essential and universal internal initiation factor, but, rather, that when it is required, its binding to the IRES helps to maintain the appropriate higher-order structure and to reverse distortions caused, for example, by an enlarged A-rich bulge.

Adenine Nucleotides↗
PubMed1998

The myxoma virus EcoRI-O fragment encodes the DNA binding core protein and the major envelope protein of extracellular poxvirus.

The nucleotide sequences of the myxoma virus gene homologs encoding the DNA binding core protein (MF17) and the major envelope protein of the extracellular poxvirus particle (MF13) have been localized to the myxoma virus 4 kB EcoRI-O fragment. The EcoRI-O fragment is located approximately 22 kb from the left end of the 163 kb DNA genome and encodes homologs of the F12L, F13L, F15L, F16L, F17R and E1L genes of the Copenhagen strain of vaccinia virus. The inferred amino acid sequences of the myxoma virus EcoRI-O encoded products have been compared to the protein databases to identify related proteins. The myxoma virus open reading frames MF12, MF15, MF16, MF17 and ME1 encode homologs of poxvirus specific proteins while the MF13 envelope protein also shares amino acid similarity with other poxvirus and cellular proteins.

Amino Acid Sequence↗
PubMed1998

Infertility in mice induced by a recombinant ectromelia virus expressing mouse zona pellucida glycoprotein 3.

Population control has become a major problem in many wildlife species. Fertility control through immunocontraception has been proposed as a method for reducing population size. We have tested the concept that immunocontraception can be achieved with a recombinant ectromelia virus expressing an ovary-specific antigen, the mouse zona pellucida 3 (ZP3) glycoprotein. Female mice infected with the recombinant virus produced autoimmune antibodies against ZP3 and were infertile for 5-9 mo after infection. For almost half the infertile mice, immunity to ZP3 was associated with a disruption of ovarian follicular development and the depletion of mature follicles without observable oophoritis. Mice returned to fertility as the anti-ZP3 antibody level in the serum decreased. Reinfection of the mice with the recombinant virus boosted the anti-ZP3 response and restored infertility.

Animals↗
PubMed1998

Parafalcine and bilateral convexity neurosarcoidosis mimicking meningioma: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Sarcoidosis is a granulomatous disorder of unknown origin that may rarely present solely as an intracranial tumor. Neurosarcoidosis can mimic more common disease processes, such as meningioma, glioma, or metastases. It is important to keep neurosarcoidosis in mind, both preoperatively and intraoperatively, to guide appropriate treatment. We present a case of neurosarcoidosis mimicking a parafalcine and bilateral convexity meningioma. CLINICAL PRESENTATION: A 44-year-old African-American woman was referred to our institution with a diagnosis of meningioma based on a 4-month history of headaches, decreased memory, personality changes, and decreased coordination and on the results of axial computed tomography, which revealed a parafalcine and bilateral convexity mass. INTERVENTION: Cerebral arteriography and magnetic resonance imaging were performed to better characterize the lesion for anticipated surgery. Despite corticosteroid therapy, the patient continued to have progressive symptoms and underwent surgery. Intraoperative frozen sections were consistent with neurosarcoidosis. The mass was then significantly debulked unilaterally. CONCLUSION: Laboratory studies and follow-up examinations revealed no evidence of systemic sarcoidosis. The patient received corticosteroid therapy and subsequently improved. Serial magnetic resonance imaging examinations during several months revealed decreasing tumor size.

Adult↗
PubMed1998

The rubella virus nonstructural protease requires divalent cations for activity and functions in trans.

The rubella virus (RUB) nonstructural (NS) protease is a papain-like cysteine protease (PCP) located in the NS-protein open reading frame (NSP-ORF) that cleaves the NSP-ORF translation product at a single site to produce two products, P150 (the N-terminal product) and P90 (the C-terminal product). The RUB NS protease was found not to function following translation in vitro in a standard rabbit reticulocyte lysate system, although all of the other viral PCPs do so. However, in the presence of divalent cations such as Zn2+, Cd2+, and Co2+, the RUB NS protease functioned efficiently, indicating that these cations are required either as direct cofactors in catalytic activity or for correct acquisition of three-dimensional conformation of the protease. Since other viral and cell PCPs do not require cations for activity and the RUB NS protease contains a putative zinc binding motif, the latter possibility is more likely. Previous in vivo expression studies of the RUB NS protease failed to demonstrate trans cleavage activity (J.-P. Chen et al., J. Virol. 70:4707-4713, 1996). To study whether trans cleavage could be detected in vitro, a protease catalytic site mutant and a mutant in which the C-terminal 31 amino acids of P90 were deleted were independently introduced into plasmid constructs that express the complete NSP-ORF. Cotranslation of these mutants in vitro yielded both the native and the mutated forms of P90, indicating that the protease present in the mutated construct cleaved the catalytic-site mutant precursor. Thus, RUB NS protease can function in trans.

Cadmium↗
PubMed1998

Iodine nutrition in the United States. Trends and public health implications: iodine excretion data from National Health and Nutrition Examination Surveys I and III (1971-1974 and 1988-1994)

Iodine deficiency in a population causes increased prevalence of goiter and, more importantly, may increase the risk for intellectual deficiency in that population. The National Health and Nutrition Examination Surveys [NHANES I (1971-1974) and (NHANES III (1988-1994)] measured urinary iodine (UI) concentrations. UI concentrations are an indicator of the adequacy of iodine intake for a population. The median UI concentrations in iodine-sufficient populations should be greater than 10 microg/dL, and no more than 20% of the population should have UI concentrations less than 5 microg/dL. Median UI concentrations from both NHANES I and NHANES III indicate adequate iodine intake for the overall U.S. population, but the median concentration decreased more than 50% between 1971-1974 (32.0+/-0.6 microg/dL) and 1988-1994 (14.5+/-0.3 microg/dL). Low UI concentrations (<5 microg/dL) were found in 11.7% of the 1988-1994 population, a 4.5-fold increase over the proportion in the 1971-1974 population. The percentage of people excreting low concentrations of iodine (UI, <5 microg/dL) increased in all age groups. In pregnant women, 6.7%, and in women of child-bearing age, 14.9% had UI concentrations below 5 microg/dL. The findings in 1988-1994, although not indicative of iodine deficiency in the overall U.S. population, define a trend that must be monitored.

Adolescent↗
PubMed1997

Oral but not parenteral interleukin (IL)-12 redirects T helper 2 (Th2)-type responses to an oral vaccine without altering mucosal IgA responses.

Our past studies have shown that the mucosal adjuvant cholera toxin (CT) induces T helper type 2 (Th2) responses with systemic IgG1, IgE and mucosal secretory IgA (S-IgA) antibodies (Abs). In this study, recombinant murine IL-12 (rmIL-12) was given either parenterally or orally to mice orally immunized with tetanus toxoid (TT) and CT to determine whether this cytokine could redirect the CT-induced Th2-type responses and what effect this shift would have on S-IgA Ab responses. Intraperitoneal administration of rmIL-12 shifted TT-specific responses toward Th1-type and resulted in CD4+ T cells producing IFN-gamma and IL-2 with markedly reduced levels of Th2-type cytokines. This cytokine profile was accompanied by increased delayed-type hypersensitivity (DTH) and shifts in serum IgG1 to IgG2a and IgG3 anti-TT Ab responses. Further, serum IgE and S-IgA Ab responses were markedly reduced by parenteral IL-12. When IL-12 complexed to liposomes was given orally both shifts to IgG2a and IgG3 and low IgE Abs again occurred concomitant with enhanced serum IFN-gamma and DTH responses. Interestingly, oral rmIL-12 did not result in significant levels of serum IL-12 nor altered S-IgA Ab responses and resulted in higher levels of some Th2-type cytokines both in vitro and in vivo when compared with parenteral IL-12. Our results show that the shifts in systemic immune responses with intact S-IgA Abs which occur after oral delivery of IL-12-liposomes are due to cytokine effects in the Peyer's patches and suggest new strategies for the targeted manipulation of Th1- and Th2-type responses to mucosal vaccines.

Administration, Oral↗