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Biomedical subjects

B A Smith

Publications and source records attributed to B A Smith.

At least 109 records · Page 6Linked to original sources
PubMed1991

Effects of metronidazole on periodontal treatment needs.

Periodontitis, a common cause of tooth loss in adult populations, is an inflammatory response to the overgrowth of anaerobic organisms such as spirochetes and bacteroides and, in some cases, micro-aerophilic organisms in the subgingival plaque. In the present investigation, using a double-blind clinical design, we sought to determine whether 1 week of metronidazole treatment plus debridement of the tooth surfaces was superior to 1 week of placebo treatment plus debridement (positive control) in reducing the subsequent amount of periodontal surgery given to the patients. Thirty-nine patients were randomly assigned to either the metronidazole or placebo (positive control) groups. All patients were given the necessary scaling and root planing and were unsupervised in their usage of the medication. After the completion of this treatment, they were reexamined and it was found that the metronidazole regimen caused a significant reduction in surgical needs of about 5 teeth per patient compared to the positive control (difference before and after treatment 8.3 +/- 6.8 teeth metronidazole versus 2.9 +/- 4.8 positive control, P = 0.007). The difference between groups was maintained during the 2 to 3 years' recall period. Metronidazole had a significant effect on the site specific reduction of spirochetes: 90% of the sites in the metronidazole group versus 64% in the positive-control group had a decrease in the percentage of spirochetes (P less than 0.05). We conclude that systemic metronidazole given 250 mg tid for 7 days in conjunction with debridement of the tooth surfaces can significantly reduce the need for periodontal surgery compared to the standard regimen which included only debridement.

Alveolar Bone Loss↗
PubMed1991

Endocrine effects of ventilation, oxygenation and cord occlusion in near-term fetal sheep.

The transition from fetal to newborn life is associated with significant endocrine changes. Some of these changes may be triggered by the effects of spontaneous respiration, increased oxygenation and removal of the placental circulation at birth. We, therefore, studied endocrine function during in utero ventilation, oxygenation and cord occlusion, in nine chronically-instrumented fetal sheep aged 137 to 140 days of gestation. During the sequential effects of in utero ventilation and oxygenation, plasma renin activity (PRA) and angiotensin II (AII) remained at control levels of 6.3 +/- 1.9 ng/ml per h and 66 +/- 15 pg/ml. After cord occlusion, PRA increased to 10.3 +/- 2.2 ng/ml per hr and AII increased to 86 +/- 24 pg/ml, the latter being non-significant. Plasma cortisol levels also increased from control levels of 3.5 +/- 1.0 to 6.7 +/- 0.8 g/dl during cord occlusion (P = 0.02). During the sequential effects of ventilation, oxygenation and cord occlusion, plasma epinephrine increased from control levels of 87 +/- 17 to 492 +/- 142 pg/ml (P = 0.04), and plasma norepinephrine levels increased slightly from 620 +/- 112 to 850 +/- 214 pg/ml. These data provide evidence that many of the changes in endocrine function seen at birth result from factors other than spontaneous respiration, oxygenation and umbilical cord occlusion.

Air↗
PubMed1991

Correlation of periodontal probe penetration and degree of inflammation.

This histological study correlated the depth of probe penetration to periodontal health in mongrel dogs. Various probing forces were also applied with an electronic pressure-sensitive probe and compared to manual probing. Three adult mongrel dogs with naturally occurring periodontitis in at least one quadrant were selected and gross scaling was only performed in these diseased areas. Mild gingivitis was diagnosed in other areas. One half was scaled and placed on a plaque control regimen to restore clinical health, while the other half remained untreated to maintain the existing gingivitis. The Gingival Index (GI) was recorded on 24 teeth achieving equal representation of different GI values. Probe tips were inserted utilizing manual pressure as well pressures of 15 and 25 gm directed with an electronic pressure-sensitive probe. The probes were bonded to the teeth, and the specimens were sacrificed. Blocks with the probes in place were fixed and decalcified. The probes were removed prior to processing. Sections from each probing site were microscopically analyzed, and the distance was recorded from the tip of the probe to the apical termination of the junctional epithelium (ATJE). The number of inflammatory cells was documented for two fields at x200, one coronal (X) and one apical (Y) to the penetration of the probe's tip. The data were analyzed by two-sample t-test and Pearson product-moment correlation coefficient. A strong correlation was established between probe penetration and degree of inflammation, X (r = 0.6936) and Y (r = 0.7075). The difference in mean inflammation scores between probes coronal or apical to the epithelium was highly significant (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Body weight and longevity in genetically obese and non-obese mice fed fat-modified diets.

Polygenically obese and genetically related non-obese male mice were fed ad libitum purified diets differing in quantity or type of fat from weaning onward to determine effects upon weight gain and life span. Non-obese mice lived 71% longer than mice in the obese line (mean = 753 d versus 441 d). Obese mice fed a low-fat diet containing 1% corn oil by weight lived 26% longer than their obese counterparts fed high fat diets containing 20% additional fat as either corn oil or beef tallow. The low fat diet had more of a normalizing effect upon longevity than upon body weight in polygenically obese mice. Conversely, dietary fat concentration had little effect upon longevity in non-obese mice and more effect upon body weight than in genetically obese mice. Type of dietary fat had little effect upon body weight and no effect upon longevity. The results of this study suggest that life span was only partially explained by body weight, and furthermore, that genetics play a greater role than body weight or dietary fat concentration in determining life span.

Animals↗
PubMed1990

Depression and anxiety among chronically ill heart patients: age differences in risk and predictors.

Anxiety and depression for 399 survivors of a 1,102-member heart disease cohort were assessed 8 to 9 years post-hospitalization. Approximately one-third reported symptoms of emotional distress and one-fourth were on anti-anxiety drugs. Predictors of anxiety and depression were analyzed through logistic regression. Subjects age 65 and over were less likely than younger patients to report anxiety or depression and also reported less heart-associated disability, the strongest predictor of distress for both age groups. Other significant predictors included a previous history of distress, low income, female sex, and beta blocker use.

Age Factors↗
PubMed1990

DNA adduct formation in target tissues of Sprague-Dawley rats, CD-1 mice and A/J mice following tumorigenic doses of 1-nitropyrene.

Recent reports have indicated that 1-nitropyrene is tumorigenic in laboratory animals. Since it is generally accepted that the covalent binding of carcinogens to DNA is causally related to tumorigenesis, we used 32P-postlabeling to examine the DNA adducts present in target tissues. 1-Nitropyrene (99.85-99.98% 1-nitropyrene, 0.15-0.02% 1,3-, 1,6- and 1,8-dinitropyrene by mass spectral analyses) was administered to Sprague-Dawley rats, CD-1 mice and A/J mice according to three tumorigenesis protocols. In DNA obtained from the injection site of Sprague-Dawley rats, two major adducts were observed. Based upon their chromatographic behavior and sensitivities to treatment with nuclease P1 and hydrazine, these adducts were identified as N-(deoxyguanosin-8-yl)-1-aminopyrene (dG-C8-AP) and N-(deoxyguanosin-8-yl)-1-amino-3-, 6- and/or 8-nitropyrene (dG-C8-ANP), which are adducts derived from the nitroreduction of 1-nitropyrene and dinitropyrenes respectively. In mammary gland DNA from Sprague-Dawley rats, two adducts were found. One of these had chromatographic characteristics and hydrazine and nuclease P1 sensitivities similar to dG-C8-AP, while the identity of the other adduct is presently unknown. The only DNA adduct detected in the livers of newborn CD-1 mice and the lungs of A/J mice was dG-C8-ANP. The presence of dG-C8-AP in the injection site and mammary gland of the Sprague-Dawley rats indicates that nitroreduction is involved in the metabolic activation of 1-nitropyrene in these tissues. Since an unidentified adduct was also found in the mammary gland, other pathways are important in this tissue. The presence of only dinitropyrene DNA adducts in the livers of CD-1 mice and lungs of A/J mice indicates that dinitropyrenes are activated very efficiently to electrophilic metabolites, to an extent far better than 1-nitropyrene.

Animals↗
PubMed1990

Furcation defects in dogs treated by guided tissue regeneration (GTR).

This study evaluated the effects of guided tissue regeneration (GTR) in the treatment of Class II furcation defects in beagle dogs. Gore-Tex periodontal material was used, and the amount of furcation fill and the surface area corresponding to new connective tissue attachment and new bone were evaluated. If present, epithelium was also evaluated. Six female dogs with naturally-occurring periodontitis were given thorough root debridement. Four weeks later mucoperiosteal flaps were raised, involving the mandibular 2nd, 3rd, and 4th premolar and 1st molar teeth. After debridement, notches were placed on the roots at the level of furcal alveolar bone. Gore-Tex material was adapted to the furcation and secured with sutures on two teeth of each quadrant. The flaps were sutured tightly, making sure the margin of the material was covered. Teeth receiving only surgery acted as controls. Gore-Tex material was removed 1 month following surgery. All dogs were sacrificed by exsanguination at 3 months. Mesiodistal sections were evaluated by descriptive histology. Surface area determination of the furcal tissues was carried out using a microscope attached to a computerized digitizer. Approximately 10 serial sections per tooth were evaluated. Mean values for each dog were obtained for experimental and control teeth and analyzed using paired t-tests (N = 6) to see whether different treatments had any effect on the parameters tested. Different degrees of fill were seen with epithelium, new connective tissue, and bone. Statistically, GTR gave significantly better results in the amount of connective tissue and bone fill achieved.

Alveolar Process↗
PubMed1990

Protective effect of Staphylococcus chromogenes infection against Staphylococcus aureus infection in the lactating bovine mammary gland.

The susceptibility of uninfected or Staphylococcus chromogenes-infected quarters to challenge with Staphylococcus aureus was measured. Seventeen S. chromogenes-infected quarters were challenged by infusion of S. aureus into the teat sinus; 47% (8 of 17) became infected and all 18 uninfected quarters challenged similarly with S. aureus became infected. No differences in daily milk yield were seen between uninfected quarters and S. chromogenes-infected quarters prior to S. aureus infusion. Postinfusion, milk yield for S. aureus-infected, S. chromogenes-infected, and S. chromogenes- and S. aureus-infected quarters differed. Somatic cell counts were elevated in S. chromogenes-infected quarters compared with uninfected quarters prior to S. aureus infusion. Somatic cell counts were not different between S. aureus- and S. chromogenes- and S. aureus-infected quarters postinfusion, but were different for S. chromogenes-infected quarters. Chloride concentrations in S. chromogenes- and S. aureus-infected quarters were different from either S. aureus-infected or S. chromogenes-infected quarters. Staphylococcus aureus colony forming units in quarters with preexisting S. chromogenes infections were lower than S. aureus colony-forming units in previously uninfected quarters. Possible protective mechanisms induced by S. chromogenes against superinfection by S. aureus are discussed.

Animals↗
PubMed1990

Analgesic efficacy and safety of single-dose oral and intramuscular ketorolac tromethamine for postoperative pain.

The efficacy and safety of the analgesic drug ketorolac tromethamine in the treatment of moderate to very severe postoperative pain was assessed in five dose-ranging studies with single-dose, double-blind, randomized, parallel-group designs. The drug was administered orally (2.5-200 mg, 352 patients in three trials) and intramuscularly (5-90 mg, 395 patients in two trials), and compared with placebo and reference drugs. Patients subjectively evaluated pain intensity and relief using verbal categoric and visual analog scales; efficacy values included pain intensity difference (PID), summed PID, and total pain relief. Oral ketorolac 10, 12.5, 100, and 200 mg were each statistically significantly superior to placebo in all efficacy measurements, and 10 mg was equivalent to intramuscular morphine 10 mg. Intramuscular ketorolac 90 mg was superior to and 10 and 30 mg were similar to intramuscular morphine 12 mg, and all of these ketorolac doses were superior to intramuscular morphine 6 mg. Intramuscular ketorolac 10 and 30 mg were superior to intramuscular meperidine 50 and 100 mg. Ketorolac was well tolerated, with rates of adverse events generally lower than those of the opiate comparators. Ketorolac doses of 2.5 and 5 mg were less effective than higher doses; 10 mg or more resulted in faster onset of action and greater peak efficacy; 90 mg or more gave more prolonged analgesic effects.

Administration, Oral↗
PubMed1990

Exercise and cardiovascular risk in black children.

The purposes of this study were to document the prevalence of cardiovascular disease risk factors in twenty black children to compare methods of measurement of blood pressure, body composition, and smoking; and to evaluate the effects of a ten week aerobic exercise training programme on blood pressure, cholesterol, smoking behaviour, and oxygen consumption. At pretest 25% of the children had blood pressures above the 90th percentile for their age or gender, 60% had a total cholesterol above 180 mg/dl and 35% exceeded 28% body fat. The mean difference score between systolic blood pressure and diastolic blood pressure measurements using a standard mercury sphygmomanometer and the Dinamap manometer was 1.5 (P less than 0.01) and 14.9 (P less than 0.0001) respectively. There was no significant difference in any of the methods used to measure body composition. Finally, there was no significant difference between the groups with regard to the dependent variables. Although the investigators identified the presence of elevated blood pressure, elevated total cholesterol, and obesity in this sample, the aerobic exercise training programme did not alter the risk profile. The authors urge caution in interpreting these results. Selection of the method for measurement of BP should be made with caution. A clear understanding of how each instrument works and its precision must be considered. Selection of the method for measurement of body composition can be based upon factors such as availability of equipment, cost, convenience, and subject preference.

Adolescent↗
PubMed1989

Catalytic effect of serum albumin on the o-rearrangement of N-sulfooxy-2-acetylaminofluorene, a potential hepatocarcinogen in the rat, to nonmutagenic sulfuric acid esters of o-amidofluorenols.

Bovine serum albumin (BSA) catalyzes the o-rearrangement of the reactive electrophile, N-sulfooxy-2-acetylaminofluorene (NSF), a potential ultimate hepatocarcinogen in the rat, to the nonmutagenic sulfuric acid esters of 1- and 3-hydroxy-2-acetylaminofluorene. Conversion of NSF was proportional to BSA concentrations ranging from 0.25 to approximately 4 mg BSA/ml incubation mixture. At concentrations greater than or equal to 5 mg BSA/ml, approximately 90% of NSF was converted to the sulfuric acid esters of the o-amidofluorenols. Human serum albumin (HSA) likewise catalyzed the o-rearrangement of NSF. However, the catalytic activity of HSA was only approximately 50% of the activity of BSA. The catalytic effect of BSA was abolished by heat denaturation. However, it was not changed by dialysis or by anion exchange chromatography. These observations indicated that the catalytic effect requires intactness of the tertiary structure of BSA and is not due to a contaminant(s) of low or high molecular weight. There were no differences in the catalytic activity of three separate fractions of chromatographed BSA, suggesting that the catalytic activity is associated with the entire BSA molecule. In contrast to serum albumin, gamma-globulin (bovine or human) did not catalyze the o-rearrangement of NSF. The solvolytic degradation of NSF to 4-hydroxy-2-acetylaminofluorene, a major reaction in the absence of BSA, occurred only to a minor extent in the presence of BSA. These data indicated that the BSA-catalyzed o-rearrangement determines the rates of concurrent reactions involved in the degradation of NSF. BSA and HSA did not catalyze the o-rearrangement of N-acetoxy-2-acetylaminofluorene (N-OAC-2-AAF), the acetate ester of N-hydroxy-2-acetylaminofluorene (N-OH-2-AAF), to the acetic acid esters of the o-amidofluorenols. These findings suggest that the albumin-catalyzed o-rearrangement occurs preferentially with esters of fluorenylhydroxamic acids that readily ionize in aqueous media.

2-Acetylaminofluorene↗
PubMed1989

Development of multiple endocrine neoplasia type 2A does not involve substantial deletions of chromosome 10.

In MEN2A both familial and sporadic cases are known. The familial cases show a dominant pattern of inheritance. In these respects, MEN2A resembles other tumors in whose etiology so-called tumor suppressor genes play a decisive role. The MEN2A locus has been assigned to chromosome 10 by linkage studies. Analysis of tumor DNA from 42 patients shows that markers on chromosome 10 were lost in only one tumor. Thus, these results contrast with previous studies which show that tumor development is generally associated with the loss of the whole or substantial parts of the chromosome on which the putative tumor suppressor gene is located.

Carcinoma↗