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Biomedical subjects

T R Williams

Publications and source records attributed to T R Williams.

At least 19 recordsLinked to original sources

Glaucoma studies in the eyeless worm: stress responsiveness and temporal expression of the Caenorhabditis elegans myocilin-like gene, cof-2.

Prolonged exposure to stress and the resulting over-stimulation of the HPA system are often detrimental to the homeostasis of an organism. In fact, chronic stress is believed to affect the pathology of several disease states including coronary heart disease and hypertension, diabetes and obesity. In humans, mutations in the GLC1A gene have been associated with primary open angle glaucoma. Previous studies on this gene have suggested that its expression is also affected by the same factors that mediate the stress response. With the ultimate goal of using the nematode, Caenorhabditis elegans, as an invertebrate model for glaucoma, we have measured the stress responsiveness of the cof-2 gene, one of two C. elegans proteins with significant homology to the myocilin olfactomedin domain. We show that both cof-2 mRNA and protein expression are developmentally regulated and that both are affected by heat shock stress.

Animals↗

Acetabular stress fractures in military endurance athletes and recruits: incidence and MRI and scintigraphic findings.

OBJECTIVE: To evaluate the incidence and the MRI and scintigraphic appearance of acetabular stress (fatigue) fractures in military endurance athletes and recruits. DESIGN AND PATIENTS: One hundred and seventy-eight active duty military endurance trainees with a history of activity-related hip pain were evaluated by both MRI and bone scan over a 2-year period. Patients in the study ranged in age from 17 to 45 years. They had hip pain related to activity and had plain radiographs of the hip and pelvis that were interpreted as normal or equivocal. The study was originally designed to evaluate the MRI and scintigraphic appearance of femoral neck stress fractures. Patients had scintigraphy and a limited MRI examination (coronal imaging only) within 48 h of the bone scan. Twelve patients demonstrated imaging findings compatible with acetabular stress fractures. RESULTS: Stress fractures are common in endurance athletes and in military populations; however, stress fracture of the acetabulum is uncommon. Twelve of 178 patients (6.7%) in our study had imaging findings consistent with acetabular stress fractures. Two patterns were identified. Seven of the 12 (58%) patients had acetabular roof stress fractures. In this group, two cases of bilateral acetabular roof stress fractures were identified, one with a synchronous tensile sided femoral neck stress fracture. The remaining five of 12 (42%) patients had anterior column stress fractures, rarely occurring in isolation, and almost always occurring with inferior pubic ramus stress fracture (4 of 5, or 80%). One case of bilateral anterior column stress fractures was identified without additional sites of injury. CONCLUSIONS: Stress fractures are commonplace in military populations, especially endurance trainees. Acetabular stress fractures are rare and therefore unrecognized, but do occur and may be a cause for activity-related hip pain in a small percentage of military endurance athletes and recruits.

Acetabulum↗

The normal response to prolonged passive head up tilt testing.

OBJECTIVE: To define the responses to head up tilt in a large group of normal adult subjects using the most widely employed protocol for tilt testing. METHODS: 127 normal subjects aged 19-88 years (mean (SD), 49 (20) years) without a previous history of syncope underwent tilt testing at 60 degrees for 45 minutes or until syncope intervened. Blood pressure monitoring was performed with digital photoplethysmography, providing continuous, non-invasive, beat to beat heart rate and pressure measurements. RESULTS: 13% of subjects developed vasovagal syncope after a mean (SD) tilt time of 31.7 (12. 4) minutes (range 8.5-44.9 minutes). Severe cardioinhibition during syncope was observed less often than is reported in patients investigated for syncope. There were no differences in the age or sex distributions of subjects with positive or negative outcomes, or in the proportions with cardioinhibitory and vasodepressor vasovagal syncope compared with previously reported patient populations. Subjects with negative outcomes showed age related differences in heart rate and blood pressure behaviour throughout tilt. CONCLUSIONS: False positive results with tilting appear to be common. This has important implications for the use of diagnostic tilt testing. The magnitude of the heart rate and blood pressure changes observed during negative tilts largely invalidates previously suggested criteria for abnormal non-syncopal outcomes.

Adult↗

Usefulness of tilt test-induced patterns of heart rate and blood pressure using a two-stage protocol with glyceryl trinitrate provocation in patients with syncope of unknown origin.

This study assesses the vasovagal collapse pattern changes, i.e, heart rate (HR) and arterial blood pressure (BP) with a 2-stage tilt-test protocol using glyceryl trinitrate (GTN) provocation. With use of the 45-minute 60 degrees head-up Westminster protocol, 102 consecutive patients were studied. Sublingual GTN 300 microg was given to those with a negative passive tilt. Heart rate and BP patterns were classified according to the Vasovagal International Study classification (VASIS) and then compared between those with a positive passive tilt and those with a positive tilt after having been given GTN. Twelve patients did not tolerate tilt testing, and 16 had a negative response despite taking GTN. Thirty-five patients (20 women and 15 men, mean age 45 +/- 21 years [mean +/- SD]) did not take GTN and 38 (26 women and 12 men, mean age 53 +/- 22 years) had positive passive test results. When comparing the VASIS classification between the 2 groups, results showed: type 1, mixed BP and HR decreased without severe bradycardia (31% [passive] vs 54% [with GTN], p = NS); type 2A, BP decreased before HR decreased (20% vs 22%, p = NS); type 2B, HR decreased before or coincident with BP (34% vs 8%, p = 0.003); type 3, BP decreased without HR decrease (9% vs 0%, p = NS); exception 1, chronotropic incompetence (0% vs 13%, p = 0.026); and exception 2, excessive HR increase (6% vs 3%, p = NS). Thus, GTN use increases frequency of positive results from 34% to 73%. Older people with chronotropic incompetence, who may benefit from pacing, were identified. In younger people there was an increase in those with cardioinhibition.

Administration, Sublingual↗

Right ventricular pressure, dP/dt, and preejection interval during tilt induced vasovagal syncope.

This study examined the potential utility of monitoring right ventricular dP/dt as a means of detecting imminent vasovagal syncope. To assess this possibility, continuous right ventricular pressure measurements were recorded in nine patients during induction of syncope by head-up tilt testing. Findings indicated that arterial pressure tended to fall prior to drop in heart rate. RV pressure exhibited a significant, but very small, fall during tilt. DP/dt max increased by 15-20% during tilt, then fell by a median of 30% from maximum value beginning about 2 minutes prior to syncope. Thus, further investigation of dP/dt as a potential marker of impending vasovagal syncope is warranted.

Adult↗

Determination of water content in bovine lenses using near-infrared spectroscopy.

Near-infrared spectral data of bovine nuclear lens tissue was collected in the 3,500- to 6,500-cm(-1) frequency range. The intensity ratios of the water peak at 5,194 cm(-1) to characteristic protein peaks at 4,862, 4,599, and 4,368 cm(-1) were determined for the nucleus of bovine lens samples. The water and protein mass percentages were determined by using a calibration curve established by spectra obtained from aqueous solutions with various concentrations of bovine serum albumin. The bovine fetal nucleus was found to contain 61.2 +/- 1.6, 61.2 +/- 1.9, and 58.4 +/- 1.9 water using the ratio of the water peak intensity to each of the three characteristic protein peaks within each spectrum. These results are consistent with other analytical techniques, thus showing the accuracy of this technique for obtaining chemical information on lens tissue.

Animals↗

Treatment of localized prostate cancer. Choosing the best alternative.

Thousands of men will be faced with a diagnosis of prostate cancer this year and will turn to their primary care physician for advice about which treatment is best. Unfortunately, there are no easy answers, and multiple factors, including the patient's age, must be weighed in decision making. In this article, Drs Williams and Love sift through the pros and cons of the available treatment options for various profiles of organ-confined disease.

Age Factors↗

Structure and regional water content of bovine, porcine, and human lenses examined with proton nuclear magnetic resonance imaging.

A proton nuclear magnetic resonance instrument with a 7-tesla field was used for nuclear magnetic resonance imaging (NMRI) to study bovine, porcine, and human lenses. The NMRI images show detailed changes in the water for normal and diseased tissues. The alterations in the nucleus and the cortex in relation to the health of the tissue are clearly illustrated.

Adult↗

Psychosocial issues in breast cancer. Helping patients get the support they need.

Patients are becoming increasingly involved in making informed choices regarding their care. However, in the case of breast cancer, more than medical treatment of a body part is at stake. The breast is an important cultural symbol of femininity and an intimate part of the patient's self-esteem. The disease and its treatment may cause ongoing sadness, fear, anxiety, and anger. Primary care physicians, because of their close relationship with patients, are often in a position to notice when natural and reasonable emotional reactions go too far or last too long. Sensitive support and education of patients who are trying to choose a treatment method may minimize anxiety. Formal programs, such as the American Cancer Society's Reach to Recovery and Look Good... Feel Better, can be very supportive. For interested patients, support groups provide a chance to freely express their thoughts and feelings. However, not all women wish to participate in programs and groups. In some cases, careful listening on the part of the primary care physician is the most powerful intervention.

Adaptation, Psychological↗

Psychogenic syncope diagnosed by prolonged head-up tilt testing.

Four patients with 'syncope' during prolonged head-up tilt testing despite normal blood pressure and heart-rate behaviour are described. They represent 5.5% of all positive tilt-test outcomes from a prospective study of 181 consecutive patients with unexplained syncope. All four patients were female, and were both younger and more symptomatic than patients with vasovagal syncope or orthostatic hypotension. In three of the patients, clinical episodes of syncope were observed which closely resembled those provoked during tilt. It is suggested that the tilt response is psychogenic and reveals a psychiatric cause for recurrent syncope.

Adolescent↗

A comparison of non-invasive continuous finger blood pressure measurement (Finapres) with intra-arterial pressure during prolonged head-up tilt.

Simultaneous intra-radial and non-invasive (Finapres, Ohmeda) blood pressures were compared during prolonged head-up tilt, in eight patients (mean age 49 years) with malignant vasovagal syncope. Twelve tilts were performed, of which eight resulted in vasovagal syncope. The mean bias (difference between Finapres and intra-arterial pressures) for systolic pressure was +0.7 mmHg (standard deviation 11.3 mmHg) and for diastolic pressure was +5.4 mmHg (standard deviation 7 mmHg). The within-tilt precision (standard deviation of the bias) of the non-invasive measurements varied between 2.9-12.4 mmHg (median 4.5 mmHg) for systolic comparisons, and 1.6-8.4 mmHg (median 4.4 mmHg) for diastolic comparisons. In all but one tilt highly significant positive increases in both systolic (median 7.1 mmHg) and diastolic bias (median 8.1 mmHg) occurred on tilt with respect to resting pre-tilt levels. Independent of the absolute level of agreement, the non-invasive measurements followed changes in intra-arterial pressure closely, with 89% of beat-to-beat changes in systolic pressure, and 95% of beat-to-beat changes in diastolic pressure followed to within +/- 2 mmHg. This study suggests that the Finapres is well suited for use during diagnostic tilt testing, demonstrating an acceptable within-tilt precision and closely following pressure changes during vasovagal syncope.

Adult↗

Norepinephrine and epinephrine levels in affected versus unaffected limbs in sympathetically maintained pain.

OBJECTIVE: To test the hypothesis that there is relative sympathetic hyperactivity in the affected limb in patients with sympathetically maintained pain syndromes by measuring serum norepinephrine and epinephrine in the affected versus the unaffected sides. DESIGN: Venous pool samples were drawn just proximal to the affected area and from an identical site on the unaffected side. Serum norepinephrine and epinephrine were measured by high-pressure liquid chromatography with electrochemical detection. SUBJECTS: Sixteen women and seven men with a mean age of 44.4 years diagnosed as having sympathetically maintained pain on the basis of a positive response to paravertebral block and a criteria-based diagnostic scheme. RESULTS: The serum norepinephrine level was significantly lower in the affected limbs than the unaffected limbs (p = 0.024). The serum epinephrine level was not significantly different. CONCLUSIONS: These results are not consistent with the hypothesis of segmental sympathetic hyperactivity in the affected limb in sympathetically maintained pain and support a hypothesis of peripheral receptor upregulation with pathologic response to circulating catecholamines. Other possible explanations are discussed.

Adult↗

Determination of the content of water in bovine corneas by differential scanning calorimetry and thermogravimetric analysis.

The 'bound', 'bulk', and total water contents in bovine corneas were investigated using differential scanning calorimetry and thermogravimetric analysis. The amount of total water (expressed as a function of total wet mass) was observed to be 83.7 +/- 1.1% using lyophilization and 84.1 +/- 0.8% using thermogravimetric analysis. These values are not significantly different from one another, but some discrepancies are observed when these values are compared with the values reported in the literature, thus indicating a need for guidelines concerning sample handling and analysis of these tissues. The 'bound' water was observed to be 62.3 +/- 2.7 (% of total water) and the amount of 'bulk' water was calculated to be 20.8 +/- 2.5 (% of total water).

Animals↗

A comparison of dental fitness classification using different class 3 criteria.

Examinations were performed on 585 Army Reserve Component soldiers during their 2-week Annual Training at Fort Pickett, Virginia, from June through September 1991. Of the 585 soldiers examined, 338 (57.8%) were in class 3 using the current DoD criteria, while 272 (46.5%) were in class 3 using the previous criteria. Of 585 paired examinations, there was agreement between the two systems in 531 (90.8%) examinations. Over 96% of the disagreement represented patients put in class 2 under the old system who were put in class 3 under the new system. In the aggregate, there were 19.3% more soldiers put into class 3 under the new system. The major source of this difference was partially erupted or pericoronally involved third molars. The increase in the class 3 proportion is due to the lack of operational criteria in the old system. Data collected under the current system provide more detailed information for administrative epidemiologic purposes. Because of the additional clinical guidelines under the current DoD criteria, the inevitable differences should be considered when pre- and post-DoD instruction dental fitness classification data are compared for a population.

Dental Health Surveys↗

Treatment needs and treatment time for soldiers in dental fitness class 2.

A systematic random sample of 962 dental records of soldiers in class 2 was reviewed by six general dentists and their estimates of periodontal and non-periodontal treatment time were recorded. The majority (88.9%) required some treatment. Periodontal treatment time ranged from 0 to 18 hours with a median and mode of 0 hours, a mean of 1.18 hours, and a standard deviation of 2.96 hours. Non-periodontal treatment time ranged from 0 to 58 hours with a median of 3 hours, a mode of 0 hours, a mean of 4.51 hours, and a standard deviation of 5.11 hours. When consultation time is included, the total time was 5.89 hours per soldier.

Adult↗

Inhibition of iron absorption prolongs the life span of Drosophila.

The life span of Drosophila melanogaster (Oregon R) males was found to be proportional to the logarithm of the iron content of the diet. Life span was also shown to be proportional to the rate of iron accumulation for Drosophila, mice and man. The total body iron content was found to correlate with the total calcium content of adult Drosophila. Iron content during the developmental stages, however, remained relatively constant and did not change with changes in the calcium concentrations. Dietary tea (Camellia sinensis) extracts were found to inhibit the ageing-related accumulation of iron and to prolong the life span of Drosophila by as much as 21.4%. It is concluded that iron accumulation is a significant factor contributing to senescence.

Absorption↗

Influence of photosensitizers and light on the life span of Drosophila.

The life span of adult Drosophila melanogaster fruit flies changed when they were fed two different photosensitizers. Methylene blue decreased the median life span by 49% when present in the food at a concentration of 0.001 M. Another photosensitizer, riboflavin, produced no changes in life span under the same conditions of a 12:12 h light/dark cycle at a daytime light intensity of 1000 lux. Flies exposed to constant darkness lived 43.2% longer than those exposed to constant light at a light intensity of 2000 lux. Under these conditions, riboflavin increased the life span of the flies exposed to constant light by as much as 25%. We conclude that riboflavin confers some degree of protection against the effects of constant light exposure. The completely different results obtained with riboflavin and methylene blue suggest a possible mechanism for photoageing involving photodynamic action mediated through the production of singlet oxygen.

Animals↗