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Biomedical subjects

K R Powell

Publications and source records attributed to K R Powell.

At least 91 records · Page 5Linked to original sources
PubMed1981

Electron microscopy of the gonococcal capsule.

Strains of Neisseria gonorrhoeae grown on agar (designated 1/2 GPH) containing peptone, hemoglobin extract, Isovitalex (BBL Microbiology Systems, Cockeysville, Maryland), and 0.05% glucose were stained with Alcian blue and examined by electron microscopy. Three of five strains had capsular material surrounding the majority of organisms. Growth of organisms to log phase and fixation and staining with Alcian blue-glutaraldehyde on the agar surface before manipulation of the organisms were important variables for the morphologic demonstration of intact capsules. Two of the three strains that were encapsulated when grown on 1/2 GPH agar were poorly encapsulated when grown on a standard gonococcal agar. Gentle washing of encapsulated organisms before fixation removed most of the capsular material. The gonococcal capsule stained with ruthenium red, which suggested that it was composed of acidic polysaccharide. Visualization of capsules on both N. gonorrhoeae and Neisseria meningitidis with ruthenium red was not as consistent as with Alcian blue, presumably because Alcian blue-glutaraldehyde not only stains but also fixes the polysaccharide.

Alcian Blue↗
PubMed1981

Caries progression in primary molars: 24-month results from a minimal treatment programme.

A 2-stage topical treatment regimen (AgF followed by SnF2) was used in an attempt to limit caries progression in the primary molars of children participating in a minimal treatment programme. The children lived in an isolated community in western New South Wales (fluoride in water less than 0.2 parts/10(6)) and were from a low socioeconomic background. The progression, over a 24-month period, of 281 established lesions in the approximal and occlusal surfaces of primary molars in 54 subjects (mean age 7.0 years) was determined from bitewing radiographs. Of the lesions studied, the majority (69%) were in dentine at baseline. At 24 months, 74% of the approximal surface lesions and 90% of the occlusal surface lesions that were in enamel at baseline remained unchanged. The greatest change occurred in the approximal surface lesions that were within 1 mm of the pulp at baseline. Only 35% of the lesions required any treatment other than topical metal fluoride therapy during the 24-month period.

Child↗
PubMed1981

Effect of stannous fluoride treatments on the progression of initial lesions in approximal surfaces of permanent posterior teeth.

Bite-wing radiographs were used to determine the effect of three forms of topical SnF2 therapy on the progression of initial lesions in the approximal surfaces of permanent posterior teeth. Radiographs were taken annually over a four-year period. The subjects were schoolchildren, aged 12-14 yr, living in a low fluoride area. The professional application of a 10% SnF2 solution for 30 s, semi-annually for two yr, had no discernible effect on the development of the initial lesions. However, the home use of a SnF2 dentifrice did inhibit caries progression appreciably at all but one of the four time intervals in the study. The professional application of a 10% SnF2 solution for 30 s, semi-annually for two yr, combined with the home use of a SnF2 dentifrice, was the most effective treatment in retarding lesion development. Even without topical fluoride therapy, the rate of progression of initial approximal lesions was generally quite slow. In view of these findings, it would seem sound clinical practice to treat all initial lesions in approximal surfaces with topical fluoride therapy and delay placement of restorations until there is radiographic evidence of lesions reaching dentin.

Adolescent↗
PubMed1980

Staphylococcal protein A adsorption of neonatal serum to facilitate early diagnosis of congenital infection.

The early diagnosis of congenital infection frequently depends on the ability to distinguish between infant IgM and maternal IgG antibodies. Staphylococcal protein A, which specifically binds IgG, removed maternal IgG from the serum of newborn infants. Residual IgM antibodies to CMV, rubella, toxoplasmosis, and syphilis were then identified by routine serologic techniques. Persistence of greater than or equal to 25% of the original antibody titer following SPA adsorption distinguished the sera of infants with congenital infection from those of healthy infants. No false negative results were encountered. Specificity of the serologic results of SPA-treated infant sera correlated with IgM-specific identification of the causative agent. Potentially false positive titers were identified by concurrent elevation of IgA or rheumatoid factor. Adsorption of cord or neonatal serum with SPA facilitates accurate serologic diagnosis of congenital infection.

Cytomegalovirus Infections↗
PubMed1980

Model of neonatal meningitis caused by Escherichia coli K1 in guinea pigs.

A total of 88 neonatal guinea pigs was inoculated intranasally with a clinical isolate of Escherichia coli K1 that had been passaged once in the peritoneum of an adult guinea pig; 74 animals became bacteremic, of which 54 had meningitis, 12 hr after inoculation. Bacteremia and/or meningitis occurred consistently in repeated experiments. It was possible to obtain serial specimens of cerebrospinal fluid by cisternal puncture without killing the animals. The induction of meningitis in a predictable fashion without disrupting the blood-brain barrier and the ability to study the cerebrospinal fluid without killing the animal make this a useful model of human neonatal meningitis caused by E. coli K1.

Aminoglycosides↗
PubMed1980

Haemophilus influenzae type b meningitis: occurrence in three siblings over a two-year period.

Haemophilus influenzae type b meningitis occurred in all three siblings in one family over a 24-month period. Investigations of the organisms involved and immunologic studies of the family revealed low percentages of E-rosette-forming cells (T-cells) in both surviving children and in the father. This report suggests that host susceptibility to H influenzae is genetically controlled and that T-cell functions, as yet undetermined, may be involved.

Female↗
PubMed1979

A clinical trial with Alice/R-75 strain, live attenuated serum inhibitor-resistant intranasal bivalent influenza A/B vaccine.

A clinical trial was conducted with Alice/R-75 strain live attenuated intranasal influenza A/B vaccine. With double blind control 88 adult volunteers were administered 2 doses of Alice/R-75 vaccine, 93 volunteers received one dose of Alice/R-75 vaccine and one dose placebo solution and 94 subjects were administered 2 doses of placebo solution. Twenty-three other subjects received Alice strain monovalent influenza A vaccine. For comparison, data from 21 subjects who received monovalent intranasal R-75 strain influenza B in two doses is included. The vaccine was generally well tolerated. Four-fold serum hemagglutination-inhibiting (HAI) antibody titer rises to A/England/42/72 occurred in 39% of the monovalent Alice strain vaccines; in contrast 18% of those given 2 doses of bivalent Alice/R-75 vaccine and 11% of those given 1 dose of bivalent vaccine had similar four-fold HAI antibody titer rises. HAI antibody titer rises to influenza B/Hong Kong/72 occurred in 38% of R-75 strain monovalent vaccinees, 14% of Alice/R-75 2-dose vaccinees and 11% of Alice/R-75 one dose vaccinees. An epidemic of influenza at onset of the study made evaluation of the efficacy of the vaccine impossible.

Administration, Intranasal↗
PubMed1979

Dental caries in susceptible fissures after prolonged fluoride application.

A prolonged fluoride application (PFA) method was used to treat susceptible fissures in 210 permanent first molar teeth in 79 children living in a fluoridated community. The development of caries in these fissures was followed for periods ranging from 2 to 4 years. At the final examination, 82.8% of occlusal surfaces in the 2-year group and 8090% of those in the 3-year group were free of detectable lesions. The corresponding value for the 4-year group was 78.9%. The mean number of treatments of these surfaces with the PFA method ranged from 1.6 for the 2-year group to 2.9 for the 4-year group.

Child↗
PubMed1979

An evaluation of BIS-GMA resin pit and fissure coatings.

A review of studies on the microleakage retention, durability, and cariostatic efficacy of BIS-MGA resin fissure sealants suggests that newly-erupted permanent molars benefit least but the benefit for premolars is consistently high. Problems arising in the assessment of the sealants in clinical trials are discussed.

Acrylic Resins↗
PubMed1977

Improved method for collection of nasal mucus.

Specimens of nasal mucus obtained after stimulaton of the mucosa with water and nasal washings from 20 volunteers were compared for content of IgA. The median concentration of IgA was 70 mg/dl in nasal mucus and 17 mg/dl in nasal washings concentrated 10-fold. The use of nasal mucus should allow for more accurate determination of nasal secretory antibody activity.

Adult↗
PubMed1977

Clinical trial with "R-75" strain live, attenuated, serum inhibitor-resistant intranasal influenza B vaccine.

The "R-75" strain live, attenuated, serum inhibitor-resistant influenza B vaccine was administered intranasally by drops in two doses 14 days apart to 21 volunteers. Each vaccinee was paired with a close associate (roommate or workmate) who similarly received two doses of a placebo solution. Although about 50% of both vaccine and placebo recipients complained of symptoms after dosage, the severity of symptoms was greater in vaccine recipients. Fourfold serum hemagglutination-inhibiting antibody titer rises occurred in 38% of vaccine recipients, and four vaccines had fourfold titer rises of nasal hemagglutination-inhibiting antibody. Vaccine virus was isolated from three asymptomatic vaccine recipients. There was no virological or serological evidence of the vaccine virus spreading to placebo recipients.

Administration, Intranasal↗
PubMed1975

A prospective search for congenital dermal abnormalities of the craniospinal axis.

Nineteen-hundred and ninety-seven consecutive term newborn infants were examined for cutaneous abnormalities of the craniospinal axis. Fifty-eight of the neonates (3%) had one or more abnormalities. The major findings included 28 (1.4%) deep dimples; 23 (1.2%) presumed sinuses; six (0.3%) skin tags,and one nodular mass. Fifty children were seen in follow-up at 4 to 12 months; in 40 infants the initial major finding persisted unchanged. Surgery has been performed on five children. One dermal sinus was found to terminate at the dura, three sinuses terminated at the coccyx, and a skin tag was associated with a fibrous band that extended to the coccyx. The management of congenital dermal sinuses is discussed.

California↗
PubMed1975

Clinical trials with Alice strain, live, attenuated, serum inhibitor-resistant intranasal influenza A vaccine.

Two clinical trials with Alice strain intranasal influenza vaccine were performed. In study no. 1 (utilizing random selection and double-blind control), 50 subjects received a bivalent inactivated influenza vaccine intramuscularly, 99 subjects received Alice strain vaccine intranasally, and 50 subjects received a placebo intranasally. No symptomatology could be attributed to the intranasal route of immunization. Convalescent-phase geometric mean titers of hemagglutination inhibition antibody were higher after intramuscular vaccination; seroconversion occurred in 16 or 17 recipients of the Alice strain, with initial titers of less than 1:8. Clinical and virologic surveillance for 20 weeks after vaccination revealed no influenza A illnesses in participants of the study. In study no. 2, 75% of the subjects with initial nasal antibody titers of less than 1:3 developed measurable nasal antibody after receiving Alice strain vaccine.

Administration, Intranasal↗