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Biomedical subjects

T G Wilson

Publications and source records attributed to T G Wilson.

At least 37 records · Page 2Linked to original sources
PubMed1998

Periodontal diseases and dental implants in older adults.

Older adults present special problems for the dentist trying to establish or reestablish esthetics. Periodontal diseases are of concern for this population since tooth loss from these widespread problems increases with age. In general, this loss occurs because of increased exposure time to pathogenic bacteria, not some change inherent in the body brought on by the aging process. The profession has begun to place more emphasis on systemic risk factors and their role in modifying periodontal inflammation. The current thinking is that bacteria are necessary to initiate and sustain periodontal diseases, but the clinical manifestation is dictated to a significant extent by systemic factors. Smoking, diabetes, and being positive for the interleukin-1 genotype predispose the patient to developing more severe disease. For those older adults who lose teeth, dental implants have emerged as reliable replacements, and concerns about placing these devices in patients who have lost teeth as a result of periodontitis appear to be largely unfounded.

Aged↗
PubMed1998

How patient compliance to suggested oral hygiene and maintenance affect periodontal therapy.

1. In medicine and dentistry, compliance tends to be poor in patients who have chronic diseases that they perceive as nonthreatening. 2. Even in the most optimistic studies, the rate of complete compliance with suggested toothbrushing is less than 50%; other studies show it much lower. In studies focusing on the use of interproximal cleaning aids, compliance is poorer still. 3. Patients in university-based programs have had a dropout rate (noncompliance) of 11% to 45%. In private periodontal practices, complete compliance was seen in one third or less of the patients. 4. The nature and the rate of disease progression affect SPT. The converse is also true. 5. In studies of the effect of therapy, it would be beneficial to record the results of treatment on all the patients, even those who drop out of therapy, to determine the part SPT plays in stabilizing the disease. 6. Patients fail to comply for many reasons, including self-destructive behavior, fear, economic factors, health beliefs, stressful events in their lives, and perceived dentist indifference. 7. By recognizing the problem, compliance can be improved in most patients. 8. There is a need for studies to define further the extent to which SPT affects the longevity of the dentition.

Attitude to Health↗
PubMed1997

Long-term duct-occluded segmental pancreatic autografts: absence of microvascular diabetic complications.

BACKGROUND: Current insulin therapies for control of glucose metabolism in patients with type I diabetes mellitus prevent major metabolic consequences of insulin deficiency, but none prevents or arrests long-term complications. In experimental models of canine diabetes, retinopathy, neuropathy, and nephropathy have been shown to develop within 5 years. The aim of this study was to determine in a canine model whether glucose control provided by segmental duct-occluded pancreas autografts could prevent the long-term complications of diabetes. METHODS: Thirty-five outbred mongrel dogs underwent segmental pancreas autotransplantation with residual pancreatectomy. Follow-up over 5 years included endocrine, retinal fundus photography, fluorescein angiography, and nerve conduction studies. At endpoint, analysis of organ specific changes was undertaken. RESULTS: Long-term survival was achieved in 14 dogs for 4 to 5 years and in 3 dogs for 3 to 5 years. Glycosylated hemoglobin levels remained within normal limits, although response to glucose challenge was suboptimal. Fundus photography and fluorescein angiography demonstrated the absence of retinal vascular aneurisms, capillary leakage, and obliteration. Retinal digest showed no vascular changes and normal endothelial/pericyte ratios. Nerve conduction was normal, and histology of nerves revealed normal density of myelinated fibers and absence of intrafascicular vessels and glycogen deposits, with no change in spectrum of fiber diameters and ovoids. Renal histology revealed no evidence of nephropathy with normal glomerular basement membranes. CONCLUSIONS: We have demonstrated that duct-occluded segmental pancreatic autografts are capable of providing satisfactory metabolic control for up to 5 years, thereby preventing development of the long-term microvascular complications of diabetes.

Animals↗
PubMed1997

Lufenuron, a chitin-synthesis inhibitor, interrupts development of Drosophila melanogaster.

The chitin-synthesis inhibitor lufenuron was administered to Drosophila melanogaster to better understand the effects of chitin-synthesis interruption during the development and reproduction of this insect. When larvae were fed a diet containing a low concentration (< 1 ppm) of lufenuron, mortality was observed during either larval or pupal development, depending on the dose. Survivor adults were unable to fly, probably due to abnormal cuticular development in the wing hinge regions of the thorax. Larvae fed a higher concentration (10 ppm) completed development within that instar, but died during ecdysis to the next instar, presumably due to inadequate cuticle synthesis. Third instar larvae pupariated, but the puparium was abnormal, and pupation did not occur. Adults fed 10 ppm showed normal viability but slightly depressed oogenesis; additionally, although their eggs were fertilized, they failed to hatch. Examination of the embryos showed that they completed development but were unable to perforate the surrounding vitelline membrane, probably due to a weakened chitinous mouth hook assembly that was insufficiently rigid to effect hatching. These results identify stages during D. melanogaster development when chitin synthesis and deposition are critical. This information will be useful for identifying chitin-synthesis mutants of this insect.

Animals↗
PubMed1997

Simultaneous pancreas and kidney transplant rejection: separate or synchronous events?

The results of simultaneous pancreas and kidney transplantation (SPK) cannot be matched by pancreas transplantation alone (PTA), in part because an independent diagnosis of pancreas graft rejection remains difficult. The relationship between rejection of the pancreas and rejection of the kidney is poorly understood, and it is not known whether simultaneous transplantation of both organs confers true protection to either graft. To study these questions, reliable canine allotransplant models of kidney transplantation alone (KTA), PTA, and SPK were established. Sixty-seven mongrel dogs received KTA (n=21), PTA (n=23), or SPK (n=23) with either no immunosuppression, low-dose cyclosporine (CsA)-based immunosuppression, or high-dose CsA-based immunosuppression. Needle core biopsy (NCB) and fine needle aspiration biopsy (FNAB) were performed at 0, 2, 4, 7, 9, 11, 14, 21, and 30 days or at the time of graft failure. Pancreas and kidney graft survival after SPK was significantly shorter in dogs given low-dose CsA than in dogs given high-dose CsA (pancreas, P<0.04; kidney, P<0.03). Concurrent NCBs and FNABs were performed on 227 occasions in pancreas grafts and 229 occasions in kidney grafts. The time to initial evidence of rejection by NCB was not different in any immunosuppressed group. Synchronous rejection occurred in 73% of immunosuppressed SPK biopsies. Kidney-only rejection occurred in 23% of biopsies and pancreas-only rejection occurred in only 3% after SPK. All markers of pancreas graft rejection were poor, with the most sensitive being NCB of the simultaneously transplanted kidney. In summary, recipients of SPK required more immunosuppression than recipients of PTA, and improved PTA survival should be achievable with more sensitive markers of rejection. Markers of kidney rejection were the most sensitive indicators of pancreas rejection, and independent pancreas rejection was uncommon after SPK.

Animals↗
PubMed1997

Vena caval resection for bulky metastatic germ cell tumors: an 18-year experience.

PURPOSE: The operative management and followup of vena caval resection for bulky metastatic germ cell tumors have been previously described in 3 series. In 1989 Ahlering and Skinner described their experience with 12 patients. We now update this experience with the most recent followup on 19 patients. MATERIALS AND METHODS: From April 1978 to May 1995, 19 men underwent retroperitoneal lymph node dissection for stage B3 (N3) or C (N3, M+) germ cell tumor after induction chemotherapy. In all cases the inferior vena cava was resected because of extensive thrombosis or direct involvement of the vessel wall by a tumor. The inferior vena cava was resected from just below the renal veins to beyond the level of disease involvement. Complete resection of retroperitoneal disease was accomplished in all patients. Morbidity and mortality were examined. RESULTS: The mean hospital stay was 10 days (range 7 to 13) for uncomplicated recoveries (9 patients) versus 19 days (range 6 to 32) for complicated recoveries (10 patients). Followup ranged from 1 month to 16 years. Complications included prolonged ileus, small bowel obstruction, fascial dehiscence and pneumonia with pleural effusion. Chronic edema persisted in 3 of 11 patients with followup of greater than 6 months. Of the 6 patients who died of disease recurrence 4 did not have normalization of tumor markers before surgery, and all 4 had persistence of cancer in the resected specimen. Seven patients are without disease at followup of 24 months to 16 years. All survivors had normalized tumor markers before surgery. Only 1 patient (5%) had retroperitoneal recurrence. CONCLUSIONS: En bloc vena caval resection for tumor involvement or extensive thrombosis can be associated with short and long-term morbidity, is feasible, and may contribute to a prolonged tumor-free interval and a chance for cure.

Adolescent↗
PubMed1997

Resistance to the insecticides lufenuron and propoxur in natural populations of Drosophila melanogaster (Diptera: Drosophilidae).

Lufenuron is a newly marketed benzoylphenyl urea chitin-synthesis inhibitor insecticide that is effective against certain insects, including Drosophila melanogaster (Meigen). Resistance to this class of insecticides is not widespread in pest insect populations and, for the resistance that has been reported, the genetic basis is not understood. In previous work, natural population strains of D. melanogaster from 2 widely separated locations in the United States were found to be as much as 100 times more resistant to lufenuron when compared with laboratory strains. It was postulated that this resistance is the result of cross-resistance that evolved to an earlier, widely used insecticide. In the current study we examined cross-resistance of selected D. melanogaster strains to propoxur, a likely candidate carbamate insecticide that has been extensively used during the past 3 decades. However, no correlation between resistance to lufenuron and propoxur was found. Strains were selected to represent a range of dates of establishment (1936-1996) from natural populations to laboratory culture. Examination of these strains showed susceptibility to propoxur in long-established laboratory strains, but resistance in recently established strains. Susceptibility to lufenuron was also high in long-established strains and apparently slowly decreased in natural populations until approximately equal to 5 yr ago, when it decreased more rapidly. These results suggest that if this loss in susceptibility results from agricultural chemical usage, then these chemicals can significantly affect a non-target insect.

Animals↗
PubMed1997

Cyromazine toxicity to Drosophila melanogaster (Diptera: Drosophilidae) and lack of cross-resistance in natural population strains.

Cyromazine is an insect growth regulator (IGR) insecticide that is effective against Drosophila melanogaster (Meigen). Both larvae and pupae of a standard laboratory strain were killed over an extremely narrow range of 0.3-0.5 ppm incorporated into the diet. Higher toxic doses killed larvae more rapidly, and lower toxic doses allowed pupariation but usually blocked pupal development. These puparia were abnormally elongated, indicating a failure of the contraction process that produces the characteristic pupal shape. When fed to adults, cyromazine had no effect on adult survival, fecundity, or fertility, even at a 10-fold larval LC50 level. In previous work, D. melanogaster strains recently derived from natural populations were found to be 25- to 100-fold resistant to at least 2 other classes of insecticides, chitin-synthesis inhibitors and carbamates. Here I tested 9 additional strains that were recently selected from widely separated geographical locations in the United States and found them to have resistance to lufenuron and propoxur, but virtually no resistance to cyromazine relative to one another or to 3 long-established laboratory strains. The results show that cross-resistance between the IGRs lufenuron and cyromazine is not present in D. melanogaster. They further suggest that cyromazine control failure in pest insect populations caused by cross-resistance may be minimal.

Animals↗
PubMed1997

The interleukin-1 genotype as a severity factor in adult periodontal disease.

Although specific bacteria, dental plaque, and age are associated with periodontal disease, there are currently no reliable predictors of periodontitis severity. Studies in twins have suggested a genetic contribution to the pathogenesis of periodontitis, but previous attempts to identify genetic markers have been unsuccessful. The pro-inflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha) are key regulators of the host responses to microbial infection. IL-1 is also a major modulator of extracellular matrix catabolism and bone resorption. We report a specific genotype of the polymorphic IL-1 gene cluster that was associated with severity of periodontitis in non-smokers, and distinguished individuals with severe periodontitis from those with mild disease (odds ratio 18.9 for ages 40-60 years). Functionally, the specific periodontitis-associated IL-1 genotype comprises a variant in the IL-1B gene that is associated with high levels of IL-1 production. In smokers severe disease was not correlated with genotype. In this study, 86.0% of the severe periodontitis patients were accounted for by either smoking or the IL-1 genotype. This study demonstrates that specific genetic markers, that have been associated with increased IL-1 production, are a strong indicator of susceptibility to severe periodontitis in adults.

Adult↗
PubMed1997

Tetracycline fibers plus scaling and root planing versus scaling and root planing alone: similar results after 5 years.

This paper presents 5-year data pertaining to a subgroup of patients from a previous investigation who were treated with scaling and root planing plus tetracycline fibers. The parent study demonstrated that 6 months after therapy, scaling and root planing plus tetracycline fiber therapy was significantly better at reducing probing depth and gaining clinical attachment than scaling and root planing alone. However, the long-term data presented here show a regression from the original gains in clinical attachment levels in the fiber group. Ultimately, the use of fibers provided no significant advantage with regards to probing depth reduction or clinical attachment gain. Within the power of this study, which would have required 1.78 mm of change in clinical attachment to show a difference, there was no significant difference between the treatments at 5 years. This study underscores the need for additional long-term evaluation of this mode of therapy.

Analysis of Variance↗
PubMed1997

Can surgery be justified for patients with periodontitis?

There is a debate concerning the role that surgical procedures should play in the treatment of inflammatory periodontal diseases. This review details some of the situations in which surgery can be of benefit. Benefits include obtaining shallower probing depths and therefore reducing the areas that are hospitable to pathogenic bacteria associated with disease. Also, removal of tooth-accumulated materials such as plaque and calculus in probing depths greater than 5 mm is more predictable with surgery. In some forms of aggressive periodontitis, elimination of potentially pathogenic bacteria is found more frequently with surgical procedures. Regeneration of lost bone and attachment apparatus are predictable only with surgery.

Gingivectomy↗
PubMed1997

Toward the validation of aneusomy detection by fluorescence in situ hybridization in bladder cancer: comparative analysis with cytology, cytogenetics, and clinical features predicts recurrence and defines clinical testing limitations.

Fluorescence in situ hybridization (FISH) is regarded as a potential new tool for the clinical management of bladder cancer that works by detecting cytogenetic aberrations in noncycling, exfoliated cells from bladder irrigations. However, clinical validation steps must be addressed to define the true predictive potential in a clinical setting. Toward the validation of FISH with the use of bladder washings and prior to incorporation into a large, prospective clinical trial, a pilot study was designed to determine its clinical potential, define testing limitations, optimize a panel of probes specific for bladder cancer detection, and outline protocol/data collection parameters. Correlations with standard cytogenetics and clinicopathological features of bladder cancer were investigated. Exfoliated cells obtained from benign bladder washings served as normal controls. The results of this pilot study suggest the following: (a) FISH and cytology are complementary testing procedures; however, the FISH data provided valuable ploidy and specific genotypic information for recurrent tumors in "suspicious" cases; (b) chromosomal aberrations defined by FISH are associated with tumor grade and stage (i.e., simple numerical aberrations were associated with low-grade tumors, and high-grade and invasive tumors exhibited multiple, nonrandom chromosomal aberrations and vast intratumor heterogeneity); (c) somatic pairing or homologous centromeric association can give a false-positive result and appears to be linked to prior therapy; (d) dual hybridization with reference gene-specific probes must be used to control for somatic pairing; and (e) focal, deep muscle invasive lesions, with no surface exposure, may yield false-negative results. The data suggest that FISH analysis, with the use of cells isolated from bladder washings, is a powerful technique holding promise for early cancer detection, monitoring treatment outcome, and predicting recurrence of disease.

Aneuploidy↗
PubMed1996

Genetic evidence that mutants of the methoprene-tolerant gene of Drosophila melanogaster are null mutants.

The Methoprene-tolerant (Met) mutation of Drosophila melanogaster results in resistance to juvenile hormone (JH) or JH analogs and appears to alter JH reception during late larval development. Several alleles of Met have been recovered from methoprene selection screens after mutagenesis with ethyl methanesulfonate, X-rays, or transposable genetic elements. The phenotype of files carrying any of these alleles is similar-resistance to the toxic and morphogenetic effects of methoprene-but otherwise is essentially wild-type. Understanding the function of the Met gene requires that we know whether these alleles are hypomorphic, producing some functional gene product, or amorphic, producing no functional gene product. This determination was made by comparing the methoprene-resistance phenotype produced by representative Met alleles with that produced by a chromosome carrying a deficiency that deletes the Met gene. The level of resistance to either the toxic or the morphogenetic effect of methoprene was similar among files heterozygous for either the deficiency chromosome or for any of the alleles. The results provide genetic evidence that the Met alleles recovered to date are amorphic and suggest that the Met gene may not be mutable to a more severe Met allele that affects the viability, development, or reproduction of the flies.

Animals↗
PubMed1996

Galanin modulates sphincter of Oddi function in the Australian brush-tailed possum.

The neuropeptide galantin (GAL) is found in neurons in the biliary tract of several species. We mapped the distribution of GAL-like immunoreactive nerve (GAL-LI) fibers in the sphincter of Oddi of the Australian brush-tailed possum by immunohistochemistry. The pharmacological effects of GAL in vitro and in vivo were studied by measuring sphincter of Oddi muscle strip contractility and transsphincteric flow, respectively. Muscle layers, and ganglionated and perivascular plexuses, contained GAL-LI nerve fibers. Exogenous GAL caused a concentration-dependent (10(9)-10(-6)M) increase in the spontaneous longitudinal but not circular muscle contractions. At 10(-6) M GAL, contractile activity was elevated two- to fourfold. This response was tetrodotoxin insensitive but competitively inhibited by galantide (10(-8)-10(-7) M). In vivo, intra-arterial bolus injections of GAL (1001000 ng/kg), decreased transsphincteric flow, with a maximum reduction to 80.2 +/- 6.8% of control. In conclusion, GAL appears to selectively stimulate longitudinally oriented sphincter of Oddi smooth muscle via a direct mechanism, which results in a modest reduction in transsphincteric flow.

Animals↗
PubMed1996

Bladder augmentation in the prevention of cyclophosphamide-induced haemorrhagic cystitis in the rat model.

OBJECTIVE: To evaluate the effects of cyclophosphamide on the bowel mucosa of the rat and to determine whether urothelium can be protected from the effects of haemorrhagic cystitis which can occur after treatment with cyclophosphamide. MATERIALS AND METHODS: Thirty Sprague-Dawley rats were divided into three groups, 10 undergoing a control (sham) operation, 10 an ileal bladder augmentation and 10 a colonic bladder augmentation. Each rat underwent the appropriate surgical procedure and after a recovery period of 2 weeks, was injected with cyclophosphamide. Urine specimens were collected 24 h after the injection and analysed for gross and microscopic haematuria. The rats were killed humanely 48 h after injection and the bladders examined for haemorrhage, oedema, attenuation, inflammation and erosion. RESULTS: None of the 20 augmented rats developed gross haematuria and only four developed microscopic haematuria, compared with the control rats where six of 10 developed gross haematuria and nine developed microscopic haematuria. In addition, the control rats had moderate to severe haemorrhage, oedema and attenuation compared with only mild changes in the augmented rats. This protection was significant for both the bowel mucosa and urothelium. CONCLUSIONS: It is possible that the administration of cyclophosphamide in patients with urinary diversion carries little risk of haemorrhagic cystitis. We propose that this protective mechanism is secondary to a substance secreted by the intestinal mucosa that may bind acrolein and render it inactive. Alternatively, this may be secondary to the production of mucus and its ability to coat and protect the epithelium.

Animals↗