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Biomedical subjects

D B Smith

Publications and source records attributed to D B Smith.

At least 145 records · Page 8Linked to original sources
PubMed1990

Hypothyroidism following radiotherapy for head and neck cancer.

Hypothyroidism is not commonly considered a complication of radiotherapy for head and neck cancer. A series of 96 patients treated with radiotherapy alone or combined with surgery for head and neck cancer was retrospectively studied. All patients had radiation ports that included the thyroid gland. Hypothyroidism after radiotherapy was documented in 26% of all patients. The majority of patients had subclinical hypothyroidism manifested by elevated thyroid-stimulating hormone (TSH) levels. The incidence of hypothyroidism dramatically increased to 65% when radiotherapy was combined with surgery that included a partial thyroidectomy. In addition, we report the unusual occurrence of massive head, neck, and hypopharyngeal edema caused by severe hypothyroidism in two patients. We advocate routine monitoring of head and neck cancer patients for hypothyroidism after radiotherapy involving the thyroid gland and recommend levothyroxine replacement therapy for subclinical hypothyroidism.

Edema↗
PubMed1990

Dizziness. A clinical perspective.

The clinical history and examination of dizzy patients leave much to be desired. Nevertheless, they are vital, as the selected treatment may be inappropriate and test data are likely to be meaningless unless interpreted in light of a thoughtful history and physical. Despite enormous variability in symptoms and signs of dizziness, the clinician must strive to categorize the patient's problems according to localization and etiology. The rules of thumb outlined above may assist in that enterprise. The remainder of this issue includes discussion of several sophisticated diagnostic tests aimed at understanding the nature of dizziness. Some of them are well established and some are investigational. Even with such a diagnostic battery, dizziness remains a perplexing problem. The complexity of the vestibular system and its interactions with visual input, somatosensory input, motor response, and conscious awareness continue to challenge our technology and our clinical acumen.

Dizziness↗
PubMed1990

Body composition, muscle and fat pad changes following two levels of dietary restriction and/or exercise training in male rats.

This study examined the effects of exercise training on conservation of lean mass during moderate and severe dietary restriction in male Sprague-Dawley rats. Eight rats each (48 total) were assigned to one of three levels of dietary restriction (ad lib., AL; moderate, MR; severe, SR) and to one of two activity levels (cage-confined, CC; or treadmill exercised, E) for a 10-week period. Post-intervention, the AL-E (91 percent), MR-CC (84 percent), MR-E (86 percent), SR-CC (66 percent) and SR-E (68 percent) groups all weighed less than the AL-CC group (427 +/- 4.3 g). Exercise training resulted in conservation of lean mass (protein + water + ash) at the moderate but not severe levels of dietary restriction. Further examination showed that this was mostly water since no between-group differences existed at any given diet level for protein or ash mass. Exercise training did elicit conservation of left ventricular heart muscle mass at both the moderate and severe levels of dietary restriction. In contrast, gastrocnemius muscle mass was conserved or maintained only at the moderate dietary restriction level. Thus, the level of dietary restriction appears to affect the ability of exercise training to elicit conservation of both total lean mass and the mass of individual muscles during diet-induced body mass reduction.

Adipose Tissue↗
PubMed1990

Population ecology and the racial integration of hospitals and nursing homes in the United States.

Although the passage of major civil-rights legislation in the 1960s compelled American hospitals to take concerted steps to achieve racial integration, nursing homes did not come under the same organizational and financial pressures to do so. As a result, nursing homes remained significantly segregated; to this day, there is a greater discrepancy between black and white people's access to long-term-care facilities than to acute-care hospitals. The perspective of population ecology may be used to help account for these disparate historical outcomes; economics, demographics, and more subtle patterns of discrimination continue to reinforce forms of segregation in health-care facilities.

Black or African American↗
PubMed1990

Neither high- nor low-intensity exercise promotes whole-body conservation of protein during severe dietary restrictions.

The effects of 11 weeks of severe dietary restriction alone or in combination with either high- or low-intensity exercise on conservation of protein were studied in 32 male Sprague-Dawley rats. The rats were assigned to one of four groups: sedentary control (C), diet restriction alone (DO) or diet restriction in combination with either high-intensity (HI) or low-intensity (LO) exercise. The groups trained at either 75 percent (HI) or 37.5 percent (LO) of maximal running speed for up to 45 or 90 min/day, 5 days/week, respectively. Total (g) proteins, fat, water and ash content did not differ between the DO, HI and LO groups and were all reduced significantly in comparison to C. Similarly, heart, gastrocnemius muscle and epididymal fat pad masses were significantly reduced for the DO, HI and LO groups in comparison to C. However, the absolute decrease in heart mass was reduced for the HI group (heart mass = 0.31 percent of body mass) in comparison to the DO group (heart mass = 0.28 percent of body mass). Thus, in lean rats undergoing severe dietary restrictions, neither high- nor low-intensity exercise appears to affect total protein conservation in comparison to diet alone. However, high-intensity exercise training appears to attenuate cardiac but not skeletal muscle mass loss in the face of severe dietary restriction.

Animals↗
PubMed1989

EMOP/CA chemotherapy for the treatment of aggressive non-Hodgkin's lymphomas.

From October 1983 to June 1987, 32 patients with aggressive non-Hodgkin's lymphomas (diffuse centroblastic, lymphoblastic and Burkitt type) were treated with the weekly alternating EMOP/CA schedule, total duration 12 weeks. There were six bulky stage II, nine stage III and 17 stage IV patients, median age 54 years (range 19-75). The complete remission rate was 59% (95% confidence limits 40-76%) and the partial remission rate 28% providing an overall response rate of 87%. With a median follow up time of 33 months (range 18-56) the relapse-free survival of those patients achieving a complete remission is 52% and the overall survival for the 32 patients treated is 27%. The CR rate for patients with stage IV disease was 47% and for those with stage II and III disease was 73% of whom 81% remain in remission. EMOP/CA chemotherapy produces acceptable results in stage II and III aggressive non-Hodgkin's lymphomas but is inadequate therapy for stage IV disease.

Adult↗
PubMed1989

Long-term outcome in patients with germ cell tumours treated with POMB/ACE chemotherapy: comparison of commonly used classification systems of good and poor prognosis.

We analysed outcome in 206 consecutive male patients treated for metastatic non-seminomatous germ cell tumour (NSGCT) of testicular or extragonadal origin treated with the POMB/ACE (cisplatin, vincristine, methotrexate, bleomycin, actinomycin D, cyclophosphamide, etoposide) regimen after division into prognostic groups by commonly used clinical classification systems and definitions of adverse prognosis. The adverse prognostic groups of all classification systems and definitions examined showed similar, but only moderate, sensitivity (71-81%) and specificity (52-56%) in predicting death. A simple definition of poor prognosis based on raised initial levels of serum tumour markers alpha fetoprotein (aFP) and human chorionic gonadotrophin (hCG) proved at least as useful (sensitivity 80%, specificity 55%) as other more complicated systems in predicting failure to achieve long-term survival. Comparison of survival between ultra-high dose cisplatin-based combination chemotherapy and patients treated with POMB/ACE shows no advantage from this more toxic approach. This suggests that good results in adverse prognosis patients can be achieved using conventional dose regimens administered intensively.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Colorimetric detection of specific DNA segments amplified by polymerase chain reactions.

The polymerase chain reaction (PCR) procedure has many potential applications in mass screening. We describe here a general assay for colorimetric detection of amplified DNA. The target DNA is first amplified by PCR, and then a second set of oligonucleotides, nested between the first two, is incorporated by three or more PCR cycles. These oligonucleotides bear ligands: for example, one can be biotinylated and the other can contain a site for a double-stranded DNA-binding protein. After linkage to an immobilized affinity reagent (such as a cloned DNA-binding protein, which we describe here) and labeling with a second affinity reagent (for example, avidin) linked to horseradish peroxidase, reaction with a chromogenic substrate allows detection of the amplified DNA. This amplified DNA assay (ADA) is rapid, is readily applicable to mass screening, and uses routine equipment. We show here that it can be used to detect human immunodeficiency virus sequences specifically against a background of human DNA.

Base Sequence↗
PubMed1989

A multicentre study of vigabatrin for drug-resistant epilepsy.

1. Vigabatrin (GVG) was given in a single-blind fashion to 89 patients with complex partial seizures (CPS) refractory to conventional drugs. 2. The median number of CPS per month decreased from 11.0 to 5.0 after addition of GVG, and 51% of patients had a 50% or greater decrease in CPS frequency (P less than 0.001). 3. Side effects (principally drowsiness, ataxia, headache) occurred mainly during the initiation of therapy and decreased during therapy. After 12 weeks on GVG side effects significantly interfered with functioning in only 13% of patients, and the efficacy: toxicity ratio warranted continued administration in 74% of patients. 4. Co-administration of GVG resulted in a mean decrease of 20% in phenytoin serum concentration (P less than 0.001). 5. Sixty-six patients having a favourable response to GVG during the single-blind study have been followed for 6-54 (median 33) months on GVG. Only 17 patients have dropped out of long-term follow-up due to break through seizures and/or side effects. No serious systemic or neurological toxicity has been detected.

Adult↗
PubMed1989

Lumbar pain in stage 1 testicular germ cell tumours: a symptom preceding radiological abnormality.

In a series of 114 stage 1 testicular tumour patients managed by a surveillance policy there have been 26 relapses. Three of these patients presented with lumbar pain as the first sign of relapse. All 3 were tumour marker non-producers and the onset of pain pre-dated radiological abnormality by up to 4 months. Stage 1 surveillance patients who develop lumbar pain must be considered to be at high risk of relapse to avoid delay in diagnosis which may prejudice survival.

Adult↗
PubMed1989

Absence of association between total heterotrophic and total coliform bacteria from a public water supply.

Heterotrophic plate counts (HPC) and total coliforms (TC) are two major microbial indicators that are used to monitor the potability of water. Although the presence of heterotrophs has been hypothesized to predict the presence of TC, there have been few documented reports. Intensive sampling of raw, treated effluent and distribution water from a public water supply serving 400,000 people provided an opportunity to study the relationship between these two indicator groups of bacteria. A total of 26,158 samples were analyzed, including 12,970 from 1986 and 13,188 from 1985. There were 13,429 samples from the distribution system, 5,524 from treatment effluents, and 7,205 from raw water. The associations between HPC and TC were made on both a hits-and-misses and numerical comparison (CFU per milliliter) basis. The periodicity of the two indicators was also analyzed to determine whether the presence of one group could predict the presence of the other. Atypical bacteria were also related to the presence of these two indicator bacteria. Venn diagrams and nonparametric statistics revealed the following correlation coefficients for HPC and TC for 1985 and 1986 combined: raw water r = 0.45, treated effluent r = 0.06, and distribution system r = 0.10. Atypical bacteria showed a similar relationship with HPC. There was no predictive periodicity for HPC and TC within +/- 10 days of isolation of each other. Therefore, in a 2-year survey of a public water supply, the presence of HPC had a low correlation coefficient with TC, as determined by hits-and-misses and numerical comparisons. The enumeration of one group was found to be independent of the other.

Enterobacteriaceae↗
PubMed1989

National field evaluation of a defined substrate method for the simultaneous detection of total coliforms and Escherichia coli from drinking water: comparison with presence-absence techniques.

A defined substrate method was applied to drinking water to simultaneously enumerate total coliforms and total Escherichia coli directly from samples. After incubation at 35 degrees C for 24 h, the development of yellow in an initially colorless solution was specific for total coliforms; fluorescence at 366 nm in the same tube(s) or vessel demonstrated the presence of E. coli. No confirmatory or completed steps were necessary. Known as autoanalysis colilert (AC), this method was constituted as a presence-absence test and compared with the methods described in Standard Methods (SM) in the P-A format. Seven water utilities representing a wide geological and hydrological spectrum participated in the evaluation. A total of 702 split drinking water samples were analyzed. Of these, 358 were negative in both tests (SM- and AC-); 302 were positive (SM+ and AC+); and 42 were mixed (SM+ and AC-, 20; AC+ and SM-, 22). The overall agreement rate was 94%. Comparison of the SM and AC results by nonparametric statistics demonstrated no differences. Heterotrophic plate count bacteria exerted no discernible effect on the AC test. By subculture, each time the AC test was yellow, a total coliform was present; when the test was fluorescent, E. coli was isolated.

Colony Count, Microbial↗
PubMed1989

O2- and pneumonia-induced lung injury. II. Properties of pulmonary surfactant.

Pulmonary surfactant was isolated from the lavage fluids of animals during the course of exposure to 100% O2, 80% O2, 40% O2, or 80% O2 plus 10(8) Pseudomonas aeruginosa instilled intratracheally and analyzed for its phospholipid composition. After 4-5 days of exposure to 100% O2, disaturated phophatidylcholine (DSPC) decreased to 87% of control, whereas the ratio of phosphatidylglycerol to phosphatidylinositol (PG/PI) was 37% of control. Longer periods of ventilation with 100% O2 resulted in DSPC falling to less than 40% of control. The injury was not reversed by reducing the O2 to 50%; rather, a progressive deterioration ensued. Acute respiratory failure (ARF) induced by 5 days of bacterial infection was very similar to that seen after 5 days of exposure to 100% O2. Ventilation with 80% O2 for 6 days resulted in smaller changes in DSPC but with differences in PG/PI comparable to those seen with 100% O2 or infection. We conclude that the ability of the type II cell to synthesize surfactant of normal composition is significantly impaired in these models of ARF. The earliest index of biochemical modification is the substantial change in PG/PI, which may be predictive of early lung injury. Further exacerbation of the injury could result in the reduction of DSPC content, with subsequent changes in lung mechanics and gas exchange.

Acute Disease↗
PubMed1989

A device for the intraoperative identification of the recurrent laryngeal nerve in piglets.

The recurrent laryngeal nerve (RLN) is one of the most frequently injured nerves in head and neck surgery. Routine identification of the RLN during thyroid surgery has reduced the injury rate from 10% to less than 4%. Difficulty in identification of the RLN contributes to this surgical morbidity. Devices previously used for intraoperative identification of the RLN have failed to achieve the simplicity and reliability necessary for clinical use. This animal study uses a simple double-ballooned endotracheal tube and pressure transducer system, which assists intraoperative RLN identification through nerve stimulation and graphic documentation of vocal fold (VF) motion. Iatrogenic injury is demonstrated by a dampened stimulation-pressure tracing. The RLNs of three piglets were injured and examined, and the degree of injury was correlated with perioperative nerve stimulation patterns. The piglet proved to be an adequate model for laryngeal research. An FDA-approved multi-institutional prospective human study using this system of identification of the RLN is in progress.

Animals↗