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Biomedical subjects

W B Davis

Publications and source records attributed to W B Davis.

At least 73 records · Page 4Linked to original sources
PubMed1983

Pulmonary oxygen toxicity. Early reversible changes in human alveolar structures induced by hyperoxia.

To study the early changes in the lower respiratory tract in persons exposed to periods of hyperoxia usually considered safe, we evaluated 14 normal subjects by bronchoalveolar lavage before and immediately after 16.7 +/- 1.1 hours of breathing more than 95 per cent oxygen. Hyperoxia caused a significant alveolar-capillary "leak" as detected by the presence of increased plasma albumin and transferrin in lavage fluid. These changes were reversible, as shown at repeat lavage in four subjects two weeks after oxygen administration. Hyperoxia for an average of 17 hours did not change the total number or type of lung inflammatory and immune effector cells recovered by lavage (P greater than 0.05, all comparisons). However, alveolar macrophages from subjects exposed to oxygen released increased amounts of fibronectin (P less than 0.05) and alveolar-macrophage--derived growth factor for fibroblasts (P less than 0.01)--mediators thought to modulate fibroblast recruitment and proliferation in the alveolar wall. Thus, although some of the effects of exposure to 17 hours of more than 95 per cent oxygen are reversible, hyperoxia for even this short period lowers the structural or functional barriers that normally prevent alveolar-capillary "leak" and induces processes that can culminate in fibrosis of the alveolar wall.

Adult↗
PubMed1983

John Staige Davis: pioneer American plastic surgeon.

John Staige Davis was the first surgeon to devote his entire practice to plastic surgery and worked exclusively for its recognition as a specialty. He wrote the first American text on plastic surgery, published 78 papers on a wide range of subjects in plastic surgery, was the first to establish a formal training program in plastic surgery in 1924, and was the first Chairman of the American Board of Plastic Surgery.

History, 20th Century↗
PubMed1981

Spinal cerebrospinal fluid leak demonstrated by retrograde myeloscintigraphy.

Cerebrospinal fluid (CSF) leaks may occur following spinal surgery and are commonly associated with infection. These leaks can be successfully evaluated with retrograde myeloscintigraphy using the same techniques applied in diagnosing CSF otorrhea and rhinorrhea. This report describes the utility of this procedure in differentiating a process due solely to postoperative infection from one that involves both an inflammatory site and a fistulous tract with the subarachnoid space.

Adult↗
PubMed1981

Toothpaste abrasive requirements to control naturally stained pellicle. The relation of cleaning power to toothpaste abrasivity.

Toothpaste abrasivity should be sufficiently high to give effective cleaning without causing mechanical damage to tooth tissue. A clinical trial carried out to measure the cleaning power of calcium carbonate toothpastes of different abrasivity is described; cleaning power is then related to in vitro dentine abrasivity measurements. These findings are used to derive an expression specifying the toothpaste cleaning power which ensures that a chosen low and cosmetically acceptable level of stain is not exceeded providing a consistent daily brushing routine is adhered to.

Calcium Carbonate↗
PubMed1980

Identification of a nicotinamide adenine dinucleotide glycohydrolase and an associated inhibitor in isoniazid-susceptible and -resistant Mycobacterium phlei.

Nicotinamide adenine dinucleotide glycohydrolase (NADase) activity was demonstrated in the catalases fraction of Sephadex G-200-chromatographed sonic extracts of isoniazid (INH)-susceptible (Inhs) and -resistant (Inhr) Mycobacterium phlei. Since crude extracts had no demonstrable activity even after heating, active fractions of the NADase were purified chromatographically by removing the inhibitor with Sephadex G-200. Assays for oxidized nicotinamide adenine dinucleotide (NAD+) hydrolytic activity were done by following the disappearance of NAD+ by the methods of alcohol dehydrogenase or cyanide addition. The NADase activity was linear with respect to time as well as concentration of enzyme and was inhibited in the presence of 0.04 M NADP, benzoic acid hydrazide, or nicotinamide. Crude extracts or pooled concentrated Sephadex G-200 fractions eluting after the catalase inhibited NADase activity by at least 70%. Inhibitor activity was present in both the Inhs and Inhr strains of M. phlei. The activity of the partially purified inhibitors was reversible by INH or nicotinic acid hydrazide at levels between 10 and 100 mM. These findings indicate that an NADase inhibitor system which is sensitive to reversal by INH functions in both the Inhs and Inhr strains; however, unlike previous studies with other mycobacterial species, the enzyme is sensitive to inhibition by nicotinamide. Furthermore, the inhibitors are heat stable and sensitive to reversal by nicotinic acid hydrazide as well as INH.

Chromatography, Gel↗
PubMed1980

Lymphocyte reactivity contributes to protection conferred by specific antibody passively transferred to herpes simplex virus-infected mice.

Passively acquired immunity to herpes simplex virus (HSV) was studied in antithymocyte serum (ATS)-treated mice and athymic nude mice to determine whether immunocompetent lymphocytes contribute to the protection observed after transfer of HSV-specific antibody to infected animals. Mice were given three intraperitoneal injections of 0.1 ml of ATS at 24-h intervals. This treatment reduced concanavalin A and lipopolysaccharide stimulation of lymphocytes harvested from these animals by 90% when compared with the stimulation of lymphocytes harvested from untreated animals. It was found that intraperitoneal injection of 0.5 ml of specific antibody 8 h after corneal HSV type 1 infection or subcutaneous HSV type 2 infection did not protect ATS-treated animals from virus infection. Specific antibody passively transferred to ATS-treated animals 8 and 120 h postinfection also failed to protect lymphocyte-depleted animals from HSV. However, ATS-treated animals were protected from HSV infection by passively acquired antibody when lymphocytes harvested from these animals regained 80% of their ability to be stimulated with concanavalin A and lipopolysaccharide. It was also found that specific antibody conferred protection to nude mice infected with HSV only if they were first reconstituted with syngeneic thymus cells 48 h before infection. The results suggest that both antiviral antibody and thymus-derived lymphocytes contribute to the recovery of HSV-infected hosts after passive immunization.

Animals↗
PubMed1980

Human alveolar macrophages: effects of endotoxin in vitro.

Experiments were performed to evaluate the in vitro effects of Escherichia coli lipopolysaccharide on viability and function of human alveolar macrophages. Alveolar macrophages were obtained by fiberoptic bronchoscopy and saline bronchial lavage from 12 normal, nonsmoking volunteers. Cells were incubated with different concentrations of E. coli endotoxin for 1 and 24 h. Endotoxin (10 microgram/ml and more) was cytotoxic for alveolar macrophages after 24 h of incubation and induced significant inhibition of phagocytosis, adherence, and spreading. The effects of endotoxin on alveolar macrophage viability and function were dose and time dependent and were not influenced by indomethacin. Thus, human alveolar macrophages, like other mononuclear phagocytes, are extremely sensitive to endotoxin effects; these observations may be relevant in conditions in which endotoxin may be in contact with alveolar macrophages in vivo: endobronchial infections with gram-negative organisms, byssinosis, chronic bronchitis of grain handles, and humidifier fever.

Adult↗
PubMed1980

Radiographic signs of pulmonary embolism.

Contrary to popular belief, the chest x-ray is abnormal in most patients with documented pulmonary emboli. Radiographic signs include elevation of the diaphragm, infiltrate without infarction, pulmonary infarction, atelectasis, pleural effusion, pulmonary edema, signs of reduced blood flow and changes in the pulmonary vasculature. Recognition of these nonspecific signs can alert the physician to the need for definitive testing by lung scanning and angiography.

Aged↗
PubMed1979

Ocular infection with herpes simplex virus type 1: prevention of acute herpetic encephalitis by systemic administration of virus-specific antibody.

The effects of virus-specific antibody on the pathogenesis of infection due to herpes simplex virus type 1 (HSV-1) following corneal inoculation of young adult mice were studied. HSV-1 was inoculated onto the corneal surface immediately after trephination with a capillary pipette. After inoculation, virus spread to the trigeminal ganglion and brain within two days and caused acute herpetic encephalitis, which killed infected animals eight to 10 days after infection. Rabbit hyperimmune antisera to HSV-1 were prepared, diluted to contain antibody at a titer of 1:150, and administered intraperitoneally to mice 8 hr after corneal infection. Administration of antisera did not interfere with the spread of HSV-1 from the site of infection to the trigeminal ganglion and brain but did reduce the multiplication of virus within the central nervous system. Reduction in viral replication resulted in complete recovery of the animals that were given antibody to HSV-1. however, the animals were not protected if they were irradiated with 390 rad 24 hr prior to administration of antibody. This observation suggested that antibody-mediated protection was not the result of in vivo neutralization of virus but instead required the presence of antibody as well as one or more radiation-sensitive components.

Animals↗
PubMed1979

Cervical enamel: a danger zone.

The British Standards Institutions's document (1974) recommending toothpaste specifications states that 'There is no evidence that any toothpaste ever produces a level of abrasion causing harm to dental enamel'. This paper questions the assumption that the enamel crown, especially at the cervical margin, is able to cope with modern dietary insult and a 'good' oral hygiene regimen, regardless of the enamel abrasivity of the dentifrice used. Once the enamel crown is breached the underlying dentine is sensitive and vulnerable to physical damage. In this work the potential rates of erosive and abrasive loss are related to the thickness of the protective enamel and to the relevance of fluoride treatments for adults. It is suggested that improvements in dental care and an increased tooth life expectancy now make the loss of tooth tissues at the cervical margin more important than is apparent at first sight.

Dental Enamel↗
PubMed1979

A comparison of dentine abrasion data generated by radiotracer and surface profilometer methods.

Six toothpastes were despatched to two research stations where a radiotracer method of dentine abrasion measurement is used (British Standards, 1974: Hefferren, 1976) and three research stations where a surface profile method is used (Ashmore, Van Abbé & Wilson, 1972). Each station measured the abrasivities of the pastes with respect to dentine by their own method. The ranges of abrasion data were found to be wider from the surface profile method than from the radiotracer method.

Adult↗