Microleakage of three generically different fluoride-releasing liner/bases

Three generically different fluoride-releasing materials that function as a liner or base were assessed for their microleakage performance on enamel and dentine. Group 1 (light-cured liner/base) showed much more leakage, but less bulk absorption of tracer, than Group 2 (traditional glass ionomer) or Group 3 (light-cured glass ionomer). The response of the three materials to tracer penetration was consistent with what is known about their chemistry. The Group 2 and 3 materials are probably the materials of choice at the caries-vulnerable margins, which are not easily visible for inspection.     

Use of ultrasound to detect intestinal wall ischemia in piglets

To evaluate the use of ultrasound (US) to detect intestinal wall ischemia, we isolated segments of jejunum on single vascular pedicles in five piglets. We sequentially clamped these segments in intervals of 0 to 6 h, reperfused them for 24 h, and then examined them in vitro histologically and with an 8.5 MHz US scan. All segments were grossly viable except those with 6 h of ischemia. Histologically, mild submucosal edema developed after 1 to 2 h of ischemia; after 3 to 4 h, mucosal necrosis, loss of folds, worsening submucosal edema, and prominent neutrophilic infiltration occurred; after 5 to 6 h, severe mucosal necrosis with hemorrhage and submucosal edema was present. Ultrasonically, we saw five wall layers in the control group corresponding to mucosa, submucosa, muscularis propria, and subserosal fat. After mild (1 to 2 h) ischemia, all layers were present except for a discontinuity in layer 3. After moderate (3 to 4 h) ischemia, the five layers persisted but with a markedly thickened submucosal layer, reduced echogenicity, and flattened mucosal folds. With severe (5 to 6 h) ischemia, we observed a loss of all normal layers with no discernible architecture. Using these US criteria, blinded observers were able to differentiate normal/mild from moderate/severe ischemia with a sensitivity and specificity of 100%. These data suggest that US can differentiate, in vitro, normal from moderate and severe degrees of intestinal wall ischemia that correlates well with the histological appearance. Endoscopic US or surgically implantable US probes can potentially help diagnose clinical intestinal wall ischemia.     

Focal oxyntic gland atrophy with endocrine cell hyperplasia in Zollinger–Ellison syndrome during omeprazole treatment

Development of focal gland atrophy of the oxyntic mucosa was found in two patients with the Zollinger-Ellison syndrome undergoing long-term treatment with omeprazole. The atrophic areas revealed florid proliferation of endocrine cells in the form of both intraglandular crescents and micronodular hyperplasia. This proliferation was significantly more pronounced than in the remaining non-atrophic mucosa. The possible relationship of these changes to long-standing pharmacological therapy for gastric acid suppression is discussed.     

Involvement of guanylate cyclase and phosphodiesterases in the functional heterogeneity of human blood platelet subpopulations

Cyclic nucleotides are involved in the regulation of platelet activation, shape change, and aggregation. In this study we have investigated the role of guanylate cyclase and phosphodiesterase in three functional heterogeneous human blood platelet subpopulations separated according to density. In low-density platelets aggregation was enhanced and inhibited less when cyclic GMP was increased by sodium nitroprusside, compared to high-density platelets. Low-density platelets possessed a lower basal level of cyclic GMP and exhibited a smaller increase in cyclic GMP after stimulation with sodium nitroprusside. Cyclic GMP-dependent phosphodiesterase activity was similar in high, low, and intermediate-density platelets. In contrast, the activity of the cyclic AMP-dependent phosphodiesterase was higher in low-density compared to high and intermediate-density platelets. These results suggest that regulation of cyclic GMP and cyclic AMP levels plays an important role in the functional heterogeneity of human blood platelets.     

Minimizing systemic absorption of topically administered ophthalmic drugs

Due to absorption several ocularly applied medications give rise to systemic side-effects. The problem of systemic drug absorption should be taken into account in designing ocular drug and dosage forms so that oculospecificity of the medications is optimized. In this review we summarize the current knowledge about the systemic absorption of ocularly applied topical drugs. Special emphasis is directed to the methods that can be used to minimize systemic absorption and increase the oculospecificity of drugs, e.g., reducing volume and increasing viscosity of eyedrops, controlling drug release from depot preparations, prodrug-derivatization, and addition of vasoconstrictive agents.     

Human papillomavirus in laryngeal papillomas and in adjacent normal epithelium

Eleven adults with laryngeal papillomas were studied for the presence of human papillomavirus (HPV) DNA by in situ hybridization. As well as from the papillomas, three additional biopsies were taken from the normal-appearing mucosa as follows: the involved vocal cord, the opposite vocal cord (when the papilloma was unilateral), and from the ventricular fold on the side of the lesion. These normal tissues were analysed by polymerase chain reaction (PCR) to detect HPV DNA. All except one of the 11 papillomas contained HPV DNA; nine were HPV 6/11 DNA positive and one positive for HPV 16 DNA. The normal-appearing laryngeal mucosa harboured HPV DNA in eight out of 11 patients. The present results strongly support the concept that the adult-type laryngeal papilloma is an HPV-induced lesion, mostly due to HPV types 6 and 11. The persistence of HPV DNA in the adjacent normal epithelium is consistent with the frequent recurrence of these lesions.     

Alaska Native Cancer epidemiology in the Arctic

Cancer incidence and its possible relation to environmental contaminants, including radiation, continues to be a perceived health threat for the arctic-dwelling Alaska Native (Inupiat Eskimo) people despite the lack of a direct link to high-dose exposure. To better understand this concern, all known malignancies diagnosed in this population (n = 177) in three consecutive eight-year periods (1971–1994) were evaluated.The most recent average incidence rate (age-adjusted to world standard population) of 315 per 100 000 (95% confidence interval, CI = 248–382) represents a 33% surge (albeit non-significant) in Alaska Native cancer incidence over the initial period studied. The male rate 366 (95% CI = 266–466) for the same period exceeds the female rate 258 (95% CI = 169–347) by 42%. Two patterns of cancer incidence are seen at the village level. One, a 24 y upward trend found in the villages of Barrow, Point Hope and Kaktovik (combined rate of increase significant [P = 0.047]) associated with lung cancer; and the other, a stable trend over the past 16 y, associated with colon and rectal cancer. Lung cancer is the predominant cancer by site and is primarily a male disease. The recent male lung cancer incidence rate of 137 (95% CI = 73–201) exceeds the female rate by greater than five times. Total lung cancer cases are primarily confined to four villages where the incidence significantly (P = 0.0043) exceeds the remaining population. The major female cancers are colon/rectal and breast with cancer of the cervix virtually eliminated. Breast cancer is found primarily in two villages where its excess is significant (P = 0.025).Inupiat Eskimo cancer epidemiology is unique, differing from both the Alaska Native and other Circumpolar populations. At present, this uniqueness cannot be explained by an overt environmental contaminant exposure. Although tobacco very likely plays a central role, it by itself cannot fully explain the extremely high male lung cancer rate and why only specific villages are affected. Genetic predisposition and environmental factors may play a synergistic role as cofactors. A cooperative investigative effort with the Inupiat population is indicated and may go a long way in reducing cancer concern in the region.     

Rheological modelling of cardiorespiratory kinetics during sub-maximal exercise

Rheological modelling of cardiorespiratory kinetics during submaximal exercise. With a view to quantify the kinetic evolution of cardiorespiratory variables during a physical exercise the concept of the viscoelastic behaviour of materials is extended to the physiological context. The method is investigated by executing a curve fitting of the observations of five groups of young adult males performing each a 60 minutes submaximal ergometry at constant intensity levels equal to 10%, 25%, 40%, 50% and 75% of their maximal work load Wmax, respectively. The rheological model consists of a fast exponential adjustment, followed by a slow linear regulation and is in accordance with the physiological concept of the non-existence of an ergometric steady state. The linear relationship between the logarithm of the rheological parameters and the work intensity allows a relatively accurate prediction of the time course of the physiological variables during sub-maximal work. Choosing a reference physiological variable (eg, heart rate) at a specific work load level (eg, 25% of Wmax) the dynamic evolution of any of the cardiorespiratory variables at any sub-maximal work load can be estimated. The ratio of the retardation time to the relaxation time of the rheological Burgers model is proposed as a quantitative index to measure the dissipated power when a subject performs a prolonged effort of constant intensity.     

Colocalization of Oestrogen Receptor lmmunoreactivity and Preproenkephalin mRNA Expression to Neurons in the Superficial Laminae of the Spinal and Medullary Dorsal Horn of Rats

A double-labelling procedure combining immunohistochemical staining with in situ hybridization using a radiolabelled cRNA probe was employed to demonstrate oestrogen receptor-like immunoreactivity and preproenkephalin-A mRNA in the medullary and spinal dorsal horn of female rats. Both markers labelled large numbers of neurons in the substantia gelatinosa and its trigeminal homologue. Many of these neurons were double-labelled, displaying both oestrogen receptor-like- immunoreactivity and preproenkephalin-A mRNA; cell counts showed that 40–60% of the of the oestrogen receptor-like-immunoreactive cells in the superficial laminae also were labelled for preproenkephalin-A mRNA, and that 60–70% of the preproenkephalin-A mRNA-labelled neurons in the same laminae displayed oestrogen receptor-like immunoreactivity. Previous studies have shown that oestrogen receptors can bind to the promoter region of the preproenkephalin-A gene, and studies on the hypothalamus have demonstrated that oestrogen regulates enkephalin expression in select neuronal populations. The present results demonstrate that enkephalinergic neurons in the superficial dorsal horn contain oestrogen receptors and suggest that oestrogen may play an important role in the modulation of sensory and nociceptive processing in the lower medulla and spinal cord.     

Bilateral acoustic neuromas

This article reviews 12 patients with bilateral acoustic neuromas. The sex incidence was equal and the mean age at diagnosis was 26.2 years. The family history was positive in nine of the patients. Five patients have had incomplete surgical removal of acoustic neuromas on both sides. Two of them are completely deaf and the other three have severe sensorineural hearing loss in one ear and no hearing in the other ear. In five patients the tumour on one side has been operated on and the other side is being observed with at least short-term preservation of good hearing. The remaining two patients died of intra-cranial complications, one of them post-operatively. Four patients developed facial palsy immediately following surgery and one developed facial weakness 6 months after surgery. Guidelines are discussed for the care of these patients including the timing of surgery and alternative treatment options (observation, radio-surgery adn chemotherapy). This is essentially a group of young individuals who have had multiple operations for bilateral acoustic tumours and associated manifestations and for whom the disease and the sequelae of treatment can be tragic.