Biomedical subjects

W S Hunter

Publications and source records attributed to W S Hunter.

At least 19 recordsLinked to original sources

PubMed1994

The CR-CO discrepancy and its effect on cephalometric measurements.

The purpose of the present study was to compare cephalometric measurements derived from a centric occlusion (CO) tracing with those of a converted centric relation (CR) tracing. The sample consisted of 68 consecutively treated patients, with a CR-CO discrepancy of 2 mm or greater in either the horizontal and/or vertical planes, measured at the condyles from mounted models. Comparisons were also made within the sample between the 39 females and 29 males; and the 35 skeletal Class I and 33 Class II patients. In analyzing the CR-CO discrepancy, the vertical component was greater than the horizontal in 96% of the sample. Every patient had a vertical component, although 10% had no horizontal component. Correlations between the horizontal discrepancy and the two tracings showed high values for approximately 50% of the measures, whereas little correlation was found with the vertical discrepancy. Paired t tests used to compare the CO and CR cephalometric values demonstrated significant differences (p < 0.05) for the majority of the values studied. However, there generally were no differences between the groups of males and females, or between the skeletal Class I and Class II individuals. The results of this study suggest that to make a correct orthodontic diagnosis the mandible should be placed in centric relation rather than in the more traditional centric occlusion.

Adolescent↗

PubMed1992

Iris sector heterochromia as a marker for neural crest disease.

A 6-month-old female infant with biopsy-proved Hirschsprung's disease had associated sector heterochromia of the irides. The association between sector heterochromia and Hirschsprung's disease has been previously reported and both conditions have been ascribed to neural crest defects. Histologic characteristics of the ocular involvement have not previously been reported, to our knowledge. Histopathologic examination of the globes revealed decreased iris stroma, decreased pigmentation in the anterior stroma, and reduced numbers of pigment-producing cells in the affected areas. Both the ocular and gastrointestinal findings reflect abnormalities in tissues of neural crest origin.

Female↗

PubMed1992

Validation of the hypothermic action of preoptic norepinephrine in guinea pigs.

Conscious guinea pigs were either microinjected intrapreoptically (iPO) with various doses of norepinephrine (NE) bilaterally or microdialyzed with pyrogen-free saline (PFS) or 10 micrograms/microliters NE unilaterally immediately and unilaterally or bilaterally 2 days after probe insertion. Core temperature (Tco), skin temperature (Tsk), and rate of oxygen consumption (VO2) were monitored continuously. The microinjection of low doses of NE induced Tco rises, whereas that of the highest dose (10 micrograms/microliters) caused an initial Tco fall followed by a rise. The microdialysis of PFS or NE immediately after probe insertion caused Tco rises; the former was abolished and the latter was converted into a fall by indomethacin (Indo, a prostaglandin synthase inhibitor) pretreatment. Two days later, PFS evoked no thermal response whereas NE induced a Tco fall; neither response was affected by Indo pretreatment. The falls in Tco produced by NE microdialyzed uni- or bilaterally were similar. The microdialysis of NE induced a 15% reduction in metabolic rate but no change in Tsk. These results indicate that the Tco rise induced by NE microinjected iPO is a methodological artifact mediated by PGE2, whereas the Tco fall observed in its microdialysis appears to represent the authentic physiological action of this transmitter effected by a reduction in metabolic rate.

Animals↗

PubMed1992

Mandibular growth direction with conventional Class II nonextraction treatment.

The purposes of this study were (1) to compare the direction of mandibular growth (MGD) during treatment and retention for a group of treated Class II patients with untreated controls, and (2) to investigate the relationship between the MGD during treatment and the pretreatment skeletal structure. Pretreatment, posttreatment, and 2 years posttreatment lateral cephalograms of 26 Class II, Division 1 subjects who were treated "nonextraction" with low- or straight-pull headgears were compared with an untreated control group of 15 subjects. Mandibular growth direction was interpreted as the movement of the point gnathion relative to the S-N line when successive tracings were superimposed on the S-N line at S. On average, MGD appeared more vertical during treatment. Posttreatment MGD was generally more horizontal than that during treatment but was also extremely variable. Three of the pretreatment skeletal measures studied, especially the articular angle (SArGo), were significantly related to MGD during treatment. The inclination of the mandibular ramus is apparently an important indicator of how mandibular growth will respond to Class II treatment mechanics.

Adolescent↗

PubMed1991

Adenoma of the nonpigmented epithelium of the ciliary body.

A 56-year-old man presented with a left ciliary body mass, anterior vitreous hemorrhage and a subluxed, cataractous lens. The clinical course included rapid enlargement of the mass, anterior uveitis, cataract progression and secondary glaucoma. Investigation included fluorescein angiography, ultrasonography and computed tomography. The eye was enucleated because of progressive enlargement with poor vision and uncontrolled secondary glaucoma. Histopathological examination showed an adenoma of the nonpigmented ciliary epithelium with cystic areas of hyaluronidase-sensitive acid mucopolysaccharide. The mass distorted the iris, occluded the angle structures and produced a complete cataract. The basement membrane of the adjacent ciliary processes was extensively thickened. The authors discuss the clinical association with vitreous hemorrhage and the local damage caused by this benign tumour.

Adenoma↗

PubMed1990

Quantitative analysis of collagen content and amino acids in trabecular meshwork.

The purpose of this study was to compare collagen content in the TM of normal and glaucomatous eyes, and to establish whether collagen levels change with age. Collagen content was measured in 30 normal and 27 age matched glaucoma trabeculectomy specimens by the sirius red dye binding technique, and in 14 normal and 15 age matched glaucoma specimens by amino acid analysis. Both dye binding data and amino acid analysis showed no statistical difference between normal and glaucoma samples. Age had no significant effect on mean optical densities or on the collagen-specific amino acids proline, hydroxyproline, and hydroxylysine. Amino acid variability, however, was statistically different between the two groups. These results indicate that mean collagen levels in the trabecular meshwork of glaucomatous eyes do not differ from those in normal eyes.

Adult↗

PubMed1990

Corneal changes in Tay-Sachs disease.

Tay-Sachs disease is a well-known inherited disease leading to an accumulation of gangliosides in the brain and retina. Our report is based on a case of Tay-Sachs disease in a non-Jewish infant where pathologic changes were noted in corneal endothelium as well as in the retina.

Corneal Diseases↗

PubMed1990

Acanthamoeba keratitis with two species of Acanthamoeba.

We describe a case of Acanthamoeba keratitis related to soft contact lens wear. The patient presented with a 3-week history of severe uniocular pain, radial stromal infiltrates and subepithelial infiltrates with no epithelial defect. Acanthamoeba was cultured from the corneal biopsy specimen, contact lens and lens case. The corneal biopsy culture grew both A. castellani and A. polyphaga as well as Escherichia coli. The patient was treated with topical dibromopropamidine isethionate (Brolene) drops, neomycin and polymyxin B drops and fortified gentamicin drops. Gradual clinical improvement ensued.

Acanthamoeba↗

PubMed1990

Acanthamoeba keratitis in a soft-contact-lens wearer.

Acanthamoeba keratitis is an uncommon but potentially devastating complication of contact lens wear. We present a case of Acanthamoeba keratitis in a soft-contact-lens wearer successfully treated with long-term medical therapy and penetrating keratoplasty. To our knowledge this is the first case of Acanthamoeba keratitis diagnosed in Canada.

Acanthamoeba↗

PubMed1989

An in vitro investigation of lingual bonding.

An in vitro investigation was undertaken to evaluate the bonding of orthodontic appliances onto lingual surfaces; 53 maxillary premolars, 37 mandibular premolars, and 37 mandibular incisors were used. Brackets were bonded onto the lingual and labial surfaces and fractured with an Instron machine. Enamel damage associated with debonding also was assessed. Results indicated comparable bond strengths (t test) on lingual (Li) and labial (La) surfaces: maxillary premolars--Li-138.2 kg/cm2, La-127.7 kg/cm2; mandibular premolars--Li-136.2 kg/cm2, La-121.6 kg/cm2; and mandibular incisors--Li-166.3 kg/cm2, La-161.1 kg/cm2. Adaptation of lingual bracket bases resulted in significantly higher lingual bond strengths for maxillary premolars (166.9 kg/cm2) and mandibular premolars (180.4 kg/cm2), but not for mandibular incisors (149.2 kg/cm2). On debonding, the percentages of lingual surfaces exhibiting horizontal "crescent-shaped" fracture lines and enamel fragment fractures were significantly higher (x2 test) than the corresponding percentages for labial surfaces: maxillary premolars--Li-67.9%, La-5.7%; mandibular premolars--Li-62.2%, La-13.5%; and mandibular incisors--Li-43.2%, La-18.9%. Furthermore, an increase in vertical enamel fracture lines (cracks) subsequent to debonding was seen labially and lingually. Bonding procedures for lingual surfaces should be identical to those advocated for labial surfaces. Care during debonding must be exercised to eliminate possible enamel damage.

Dental Bonding↗

PubMed1988

Prenatal diagnosis of del(11)(p13p15).

Prenatal diagnosis of del(11)(p13p15) was made on cultured amniotic fluid cells and confirmed on fetal skin fibroblasts after termination of pregnancy. Both irides appeared behind schedule in development by 2-3 weeks in reference to the gestational age of the fetus. It is suggested that the aniridia of the aniridia--Wilms tumour association is due to developmental arrest. Confirmation of this complex is difficult at mid-gestation without critical pathological study of the eyes.

Adult↗

PubMed1987

Thermal stimulation of the hypothalamus does not evoke the acute-phase reaction.

Interleukin-1 (IL1) injected into the preoptic-anterior hypothalamus (POAH) induces, besides fever, the hepatic synthesis of acute-phase glycoproteins. Since the febrigenic action of IL1 may involve thermosensitive neurons in the POAH, this study examined whether such neurons also might mediate the acute-phase response (APR). The POAH of six adult NZW rabbits was cooled (Tpo = 34.4 +/- 0.4 degrees C [mean +/- SD]) or heated (40.6 +/- 0.2 degrees C) continuously for 2.5 hr (so as to mimic the mean febrile course following a bolus microinjection of IL1 into the POAH). The ambient temperature (Ta) was 23.5 +/- 1.0 degrees C. Expectedly, core temperature fell and skin temperature rose on POAH heating, and the opposite occurred on POAH cooling. However, no statistically significant changes in the plasma levels of Fe, Zn, Cu, and N-acetylneuraminic acid, as indices of the APR, were induced by these treatments. These results indicate, therefore, that the central actions of IL1 in inducing fever and the APR are separate, and that the APR is not mediated through stimulation of thermosensitive units in the POAH.

Acute-Phase Proteins↗

PubMed1987

The effects of Fränkel II treatment on arch width and arch perimeter.

Changes in dental arch width and total arch perimeter in 24 Class II, Division 1 patients treated with the Fränkel II appliance were compared with changes in an untreated control group. Measurements were made on pretreatment and posttreatment plaster casts at three points on each of four maxillary and four mandibular teeth. Increases in width were computed at the occlusal point and compared for the two samples. A significant increase in occlusal arch width for all measures was suggestive of both a minor tipping movement of the maxillary teeth and a bodily movement of the mandibular teeth. Width development in the maxilla was greater than in the mandible. Occlusal arch width increased more in the molar and premolar regions in the maxilla and in the premolar region in the mandible. Wide arches were found to have as much increase as narrow arches. The total arch perimeter decreased significantly less in the treatment sample than in the control sample. The documented gains in arch width and arch perimeter would not be sufficient to relieve severe crowding, but could be useful in avoiding removal of teeth in borderline extraction cases.

Activator Appliances↗

PubMed1987

The depth of the mandibular antegonial notch as an indicator of mandibular growth potential.

The craniofacial characteristics and growth potential of 25 orthodontically treated patients with deep mandibular antegonial notch were compared with a similar group of 25 shallow notch subjects by the use of longitudinal lateral cephalometric radiographs. Deep notch cases had more retrusive mandibles with a shorter corpus, smaller ramus height, and a greater gonial angle than did shallow notch cases. The lower facial height in the subjects with a deep mandibular notch was found to be longer, and both the mandibular plane angle and facial axis were more vertically directed. During the average 4-year period examined, the deep notch sample experienced less mandibular growth as evidenced by a smaller increase in total mandibular length, corpus length, and less displacement of the chin in a horizontal direction than did the shallow notch sample. The results of this study suggest that the clinical presence of a deep mandibular antegonial notch is indicative of a diminished mandibular growth potential and a vertically directed mandibular growth pattern.

Adolescent↗

PubMed1987

Neodymium-YAG transscleral cyclocoagulation in rabbit eyes.

Transscleral ruby cyclocoagulation has been successfully used to lower intraocular pressure. The recent commercial availability of Nd-YAG lasers with a thermal mode provides a possible alternative by which to perform this procedure. We treated one eye of seven pigmented rabbits using the thermal mode of the Nd-YAG laser. The intraocular pressures were followed up for three months. The treated eyes had significantly lower mean intraocular pressures were followed up for three months. The treated eyes had significantly lower mean intraocular pressures than the untreated contralateral eyes (p less than 0.001). Moreover, the decrease was sustained over the three-month duration of the study. Pathological examination revealed very selective destruction of the ciliary processes, with sparing of the overlying ciliary muscle, sclera, and conjunctiva. The potential value of this mode of therapy for use in patients with glaucoma is discussed.

Animals↗

PubMed1987

Thermoregulatory responses of guinea pigs with anteroventral third ventricle lesions.

Guinea pigs with anteroventral third ventricle region (AV3V) lesions fail to develop fever and the associated rise in acute-phase plasma protein levels following systemic injections of lipopolysaccharide (LPS). Since endogenous pyrogen (EP) injected directly into the preoptic area of animals with AV3V lesions causes appropriate elevations in core temperature (Tco) and acute-phase plasma proteins levels, the blocked responses to LPS probably are not due to damage to the adjacent preoptic area. We proposed, therefore, that EP may pass from blood into brain in the AV3V, presumably through the organum vasculosum laminae terminalis. However, the possibility that a more generalized impairment due to damaged pathways within the AV3V could account for the observed effects was not examined. To investigate this possibility, guinea pigs were given AV3V lesions. Pending histological verification of the ablated sites, AV3V lesions were presumed to be placed correctly if the animals did not develop fever following LPS (Salmonella enteritidis, 2 micrograms/kg i.p., at ambient temperature (Ta) 22 degrees C); those failing to meet this criterion were designated as sham-operated. Two experiments were conducted. In the first, metabolic rates, Tco, and two skin temperatures (Tsk) were measured at Ta 12 degrees, 22 degrees, and 32 degrees C over an 8-month postlesion period during which failure to fever persisted; the data were collected during a 30-min period after thermal balance had been achieved at any given Ta. There were no differences in the variables measured between sham-operated and AV3V-lesioned animals at Ta 22 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Regional surface areas of spontaneously hypertensive and Wistar-Kyoto rats.

Regional skin surface area and region-specific weighting factors for calculating mean skin temperature have not been determined for the rat. Therefore, measurements were made of total skin surface area segmented into five regions of 12 spontaneously hypertensive (SHR) and 12 normotensive Wistar-Kyoto (WKY) rats. SHR's were selected because chronically elevated core temperature and reduced ability of SHR's to withstand heat stress make them of interest for thermoregulatory studies. Area was determined by coating the skin with rubber base dental impression material, then measuring the area of the coating. The relationship between total skin surface area and mass of SHR's was not different from that of WKY's and is described by the equation SA = 8.62 M0.67. However, the ears of SHR's had larger surface area and their tails smaller surface area than those of WKY's. For the combined groups, the proportion of total surface area of the regions was as follows: ears, 0.022; front feet, 0.017; hind feet, 0.040; tail, 0.100; central skin, 0.826. These data provide a basis for calculating skin surface area, mean skin temperature, and related values for SHR and WKY rats.

Animals↗

PubMed1987

Factors producing elevated core temperature in spontaneously hypertensive rats.

Core temperature (Tco) of the spontaneously hypertensive rat (SHR) is consistently higher by approximately 1 degree C than that of normotensive controls. To analyze factors producing the elevated Tco, mean skin temperature (Tsk), metabolic heat production (M), respiratory evaporative heat loss (Eres), effective tissue thermal conductance (K), systolic blood pressure (BP), and Tco were determined in eight male SHR and nine male normotensive Wistar-Kyoto (WKY) rats habituated to rest quietly in neck stock restraint while exposed to ambient temperatures (Ta) of 12.5, 17, 23, 28.5, 32, 34, and 35 degrees C. At all temperatures steady-state BP, Tco, and M were higher for SHR's than for WKY's. SHR's could maintain thermal balance up to Ta 32 degrees C, and WKY's up to 34 degrees C. Eres from SHR's was greater than from WKY's at Ta of 12.5, 17, and 28.5 degrees C. K of SHR's was not different from or was higher than K of WKY's, and K for both groups was 2.6 times greater at Ta 32 degrees C than at 17 degrees C. These results indicate that the high Tco of SHR's is due to increased M uncompensated by increased K or Eres.

Animals↗