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Biomedical subjects

R Sawyer

Publications and source records attributed to R Sawyer.

At least 73 records · Page 4Linked to original sources
PubMed1975

Contaminants in food: analytical problems and achievements.

In evaluating the toxicological significance of such contaminants as trace metals, polynuclear aromatic hydrocarbons, mycotoxins, pesticides and nitrosamines, analytical chemistry plays an important role. The detection and identification of these in various foods at the mg/kg or mug/kg levels has posed some difficult analytical problems. Considerable progress has been made in this field in the past decade, however, an opportunity is taken to review the achievements in terms of specificity and sensitivity for each class of contaminant.

Anti-Bacterial Agents↗
PubMedDate not supplied

Tracheogastric puncture for vocal rehabilitation following total pharyngolaryngoesophagectomy.

Speech rehabilitation postpharyngolaryngoesophagectomy has not received significant emphasis. We describe our experience with five patients who underwent a delayed tracheogastric puncture (TGP) after pharyngogastric anastomosis. When compared to patients who had undergone tracheoesophageal puncture (TEP) after laryngectomy, speech intelligibility and fluency were adequate for conversational speech, but voice quality was characterized by lower pitch, reduced intensity, slower rate, and a "wet" quality. There were no complications related to the TGP. TGP is a safe and often useful procedure for voice and speech restoration in patients who have undergone total pharyngolaryngoesophagectomy and pharyngogastric anastomosis.

Aged↗
PubMedDate not supplied

Push-enteroscopy for diagnosis of patients with gastrointestinal bleeding of obscure origin.

Push-enteroscopy using a disinfected colonoscope was performed on 39 patients with gastrointestinal bleeding of obscure origin. Our results show that: (1) A high percentage of patients (38%) have pathological lesions responsible for bleeding located in the distal duodenum and proximal jejunum, which are readily detected by push-enteroscopy. (2) Duodeno-jejunal arteriovenous malformations (AVMs) are the most common cause for bleeding, and these lesions can be conveniently cauterized through the endoscope. (3) An efficient sequence of steps for diagnosis of patients with this problem includes push-enteroscopy when the initial EGD and colonoscopy are normal followed by small bowel radiography. Mesenteric angiography and intraoperative enteroscopy can be reserved for patients with severe bleeding when push-enteroscopy and small bowel radiography are negative. We conclude that push-enteroscopy has an important role to play in the early assessment of patients with gastrointestinal bleeding of obscure origin.

Arteriovenous Malformations↗
PubMedDate not supplied

Effects of rate of force development on EMG amplitude and frequency.

The purpose of this study was to compare the amplitude and frequency of the gastrocnemius EMG during ramp and ballistic contractions in highly trained sprint athletes. Sixteen female sprinters performed ramp and ballistic isometric contractions on a Biodex dynamometer. RMS and median frequency of the gastrocnemius EMG signals were obtained at the following torque levels: 25 +/- 5 %, 50 +/- 5 %, 75 +/- 5 %, 100 % MVC. The average rate of force development (RFD), was 610.2 +/- 123.1 N . m/s and 212.3 +/- 155.6 N . m/s for the ballistic and ramp contractions, respectively. In the ramp contractions the EMG amplitude increased as a function of torque. In the ballistic contractions the EMG amplitude decreased from 25 % to 100 % MVC. The highest RFD of 889.45 N . m/s was generated in ballistic contractions by a muscular activation pattern with high EMG amplitude (475.7 microV) and low frequency (116.7 Hz) at 25 % MVC. The findings suggest that the CNS utilizes different muscular activation patterns to modulate RFD in ramp and ballistic contractions. In ramp contractions the EMG amplitude increased linearly with force. In ballistic contractions a high RFD is generated with a muscular activation pattern consisting of high amplitude and low frequency at the start of the contraction.

Adult↗
PubMedDate not supplied

Role of vascular alpha 2-adrenoceptors as targets for circulating catecholamines in the maintenance of blood pressure in anaesthetised spontaneously hypertensive rats.

We examined the blood pressure-lowering effects of the alpha 2-adrenoceptor antagonist rauwolscine in anaesthetised spontaneously hypertensive rats (SHR). In the absence of prior drug, rauwolscine (1-10 mg kg-1) produced dose-dependent falls in diastolic blood pressure (DBP). In the presence of prazosin (1 mg kg-1) to eliminate alpha 1-adrenoceptor-mediated responses, rauwolscine (0.1-1 mg kg-1) lowered DBP in unoperated and sham-operated animals but not in adrenal demedullated animals. Hence, we were able to demonstrate that alpha 2-adrenoceptors are involved in the control of blood pressure in intact anaesthetised SHR but not following adrenal demedullation, suggesting that circulating catecholamines are responsible for these alpha 2-adrenoceptor-mediated pressor effects.

Adrenal Medulla↗
PubMedDate not supplied

The inevitability of renal function loss in patients with hypercreatinemia.

UNLABELLED: Although it is anticipated that most patients with renal insufficiency will progress towards end-stage renal disease (ESRD) there have been few population-based studies to validate this assumption. We examined serial creatinines from 3,874 anonymous patients at an urban VA medical center who had a baseline creatinine of 1.4 mg/dl or greater to estimate the frequency of deterioration in renal function (DRF). DRF was defined as the first Cr (1stCr) value being lower than the last Cr (LCr) for each patient. The median follow-up was 48.3 +/- 0.5 months with 18 +/- 0.5 creatinine values per patient. The median 1stCr was 1.6 +/- 0.1 mg/dl with 32.2% of the patients having a 1stCr greater than or equal to 1.7 mg/dl. In the study group, 1,723 (44.4%) had DRF including 1,089 (41.4%) of those patients with a 1stCr of 1.4-1.7 mg/dl. However, 45 (36.6%) of those with a 1stCr value 3.0-5.0 mg/dl did not have DRF, the percent with stable creatinine in this group did not vary with length of follow-up. Over the study period, 299 (7.7%) of all the patients had a creatinine rise to 7.0 mg/dl, with 104 (4%) of those with a 1stCr of 1.4-1.7 mg/dl reaching this endpoint. CONCLUSION: A majority, but not all, patients with renal insufficiency lose renal function over time and those with even mild hypercreatinemia are at risk for deterioration in renal function. Hypercreatinemia, however, does not accurately discriminate between those renal insufficiency patients who are stable versus those at high risk for ESRD.

Analysis of Variance↗