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Biomedical subjects

J J Davis

Publications and source records attributed to J J Davis.

36 records · Page 2Linked to original sources
PubMed1989

Modification of the silver impregnation technique of Bielschowsky for use in glycol methacrylate-embedded brain tissue.

The modified Bielschowsky stain has become the standard silver impregnation technique for use in paraffin-embedded tissue sections for identifying abnormalities of neuritic processes in a variety of neurodegenerative disorders such as Alzheimer's disease. Recently, glycol methacrylate embedding has been used increasingly as a substitute for paraffin embedding of tissue, because it results in less tissue distortion during processing and provides greater clarity and resolution of cellular architecture and structural details. We have been able to modify the Bielschowsky stain for use in glycol methacrylate-embedded brain sections. The use of this technique will permit more accurate quantitation of the histopathologic changes in neuritic processes in neurodegenerative diseases.

Acrylates↗
PubMed1988

Longitudinal pulmonary function changes in pigeon breeders.

We studied 15 subjects (14 men and one woman; seven symptomatic and eight asymptomatic) at three- to four-year intervals from 1967 through 1985 (18 years) to determine if continued pigeon antigen exposure in these groups was associated with a decline in pulmonary function greater than expected in healthy individuals. We collected immunologic studies at the initial visit, performed sequential pulmonary function studies and obtained chest radiographs. After compensating for the normal changes expected with increasing age, we found the declines in FVC, FEV1, and Dsb in the symptomatic group were nearly four times greater than expected. There was no significant difference in the decline of pulmonary function between asymptomatic subjects and the normal predicted declines with increasing age. We conclude that, if an individual has episodes of acute hypersensitivity pneumonitis, long-term exposure to pigeon antigens will result in an accelerated decline in pulmonary function.

Adult↗
PubMed1987

Sclerosing cholangitis associated with chronic cryptosporidiosis in a child with a congenital immunodeficiency disorder.

Primary sclerosing cholangitis (PSC) in children is a rare and incurable disorder of unknown etiology. We report an immunodeficient child with chronic cryptosporidiosis of the biliary tract leading to clinical, pathological, and radiographic findings consistent with PSC. This case documents the ability of Cryptosporidium to disseminate to extraintestinal organs, and suggests that chronic cryptosporidial infection of the biliary tract may be one etiological mechanism producing sclerosing cholangitis in immunodeficient children. The increased incidence of PSC in immunodeficient children may in part be due to their inability to resolve infections of the biliary tract, which may result in sclerosing cholangitis mimicking PSC. We submit that an aggressive diagnostic workup should be performed to rule out an infectious etiology of sclerosing cholangitis in immunodeficient patients who have findings of PSC, because specific chemotherapy against the infecting organism would potentially arrest progressive biliary obliteration.

Adolescent↗
PubMed1976

Diagnosis and management of blunt abdominal trauma.

The records of 437 patients with blunt abdominal trauma admitted to Charity Hospital, New Orleans, from 1967-1973 have been reviewed and computer-analyzed. There was an 80% increase in the incidence of blunt abdominal trauma when compared with the preceding 15-year experience. Forty-three per cent of all the patients presented with no specific complaint or sign of injury. Blunt abdominal injury was usually diagnosed preoperatively using conventional methods including history, physical examination, and routine laboratory tests and x-rays. Abdominal paracentesis via a Potter needle had an 86% accuracy. The incidence and management of specific organ injuries with associated morbidity and mortality have been discussed. Mortality and morbidity continue to be significant in blunt abdominal trauma. Isolated abdominal injuries rarely (5%) resulted in death, even though abdominal injuries accounted for 41% of all deaths. Associated injuries, especially head injury, greatly increased the risk. The insidious nature of blunt abdominal injury is borne out by the fact that more than one-third of the "asymptomatic" patients had an abdominal organ injured. A high index of suspicion and an adequate observation period therefore are mandatory for proper care of patients subjected to blunt trauma.

Abdominal Injuries↗
PubMed1969

Evidence for multiple gene control of a single polypeptide chain: the heavy chain of rabbit immunoglobulin.

To determine the chemical basis for rabbit heavy chain allotypes, amino acid analyses were carried out on IgG and IgM antibodies isolated from rabbits which were homozygous a1 or a3 for the gamma chain locus and homozygous b4 for the light chain locus. The compositional differences between a1 and a3 IgM antibodies were found to be identical to those between their IgG counterparts. The identity of the allotypic amino acid replacements showed that the same genetic markers were present in the variable sequences of IgG and IgM heavy chains. Since the constant sequences of these heavy chains are controlled by different loci, these data demonstrated that rabbit heavy chains are coded by two separate germ-line genes, one producing the variable region and a second one of various genes producing the constant regions. The use of two antibodies, antiazophenylarsonate and antiazophenyl-beta-lactoside, permitted the compositions to be compared also on the basic of immunological specificity. The specificity amino acid replacements were found to be identical in the IgM and IgG heavy chains whether the two antibodies were isolated from and individual animal of a1 or a3 allotype. These results further support the conclusions of the allotype measurements that at least two genes code for the rabbit heavy chain.

Amino Acid Sequence↗
PubMedDate not supplied

The tunnelling conductance of molecularly ordered metalloprotein arrays.

Metalloproteins can be self-assembled in molecularly ordered, electrochemically addressable arrays. We report here on a study of the transport characteristics of the blue copper protein, azurin, from Pseudomonas aeruginosa, by a combination of electrochemical and scanning probe techniques (scanning tunnelling microscopy and conducting atomic force microscopy). Redox-switchable chemisorbed molecular arrays can be formed from both wild-type and mutant proteins using the strong affinity of cysteine residue thiolates for pristine gold surfaces. The molecular transconductance of single protein molecules within these arrays has been studied under controllable conditions where it has been additionally possible to resolve the effects of protein mechanical perturbation. Although tunnelling appears to be non-resonant and adequately explained through the use of a square barrier model, under some conditions the contribution of the redox-active copper centre to conductance is resolvable.

Azurin↗
PubMedDate not supplied

Lead bioavailability in the environment of children: blood lead levels in children can be elevated in a mining community.

Lower blood lead averages in mining communities, compared with other child exposure settings, e.g., innercity areas of the United States and smelter communities, have been attributed to lower bioavailability of lead to children in the mining areas. Direct supporting evidence of the lower bioavailability has, however, generally been lacking. Elevated blood lead levels for approximately 85% of children with > 10 micrograms/dl have been reported from the Broken Hill mining community in Australia. Lead isotope, optical, and scanning electron microscope analyses on the lead species from soils and dusts show them to be derived mainly from weathered ore body material. Solubility tests using 0.1M HCl on the -53 + 38 microns fraction of soil and dust show the lead species to have a high degree of bioavailability. Ingestion of soil and dust, either directly or via mouthing activity, is the main source and pathway for elevated blood lead in children from this community.

Australia↗
PubMedDate not supplied

Riskier than we think? The relationship between risk statement completeness and perceptions of direct to consumer advertised prescription drugs.

Direct to consumer (DTC) prescription drug advertising is one of the fastest growing categories of advertising. Expenditures have increased from about $25 million in 1992 to nearly $2 billion in 1999. Given strong evidence of consumer-driven demand for advertised prescription drugs, research was conducted to assess the extent to which DTC prescription drug advertising provides consumers with the information they need to make an informed evaluation of an advertised drug's relative benefits and risks. Two studies explored the relationship between the completeness of the statement describing drug-associated side effects (the "risk statement") and consumers' perceptions of a drug's safety and appeal. The research manipulated risk statement completeness with regard to the incidence levels of side effects mentioned in the statement (which in turn affected the number of side effects mentioned) and the presence or absence of a numeric indicator of side effect incidence. The research strongly suggests a direct relationship between risk statement completeness and consumers' perceptions of drug safety and appeal. Consumers rate the safety and appeal of drugs described with an incomplete risk statement significantly more positively than comparable drugs described with a more complete risk statement. Implications of the research for the regulation and presentation of DTC prescription drug advertising and advertiser communication practices are discussed.

Adult↗
PubMedDate not supplied

A blueprint for green marketing.

Companies have rushed to market environmentally acceptable products. But according to the author, many have ignored the planning considerations that should have preceded the development and promotion of these "green" products.

Advertising↗