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Biomedical subjects

P Lawrence

Publications and source records attributed to P Lawrence.

At least 37 records · Page 2Linked to original sources
PubMed1992

Bullous secondary syphilis.

An earlier standard syphilology textbook states that 'If vesicles are an essential part of an eruption in an adult, the lesions are not due to secondary syphilis'. However, vesicular and bullous eruptions do occur in congenital syphilis and rare reports of both vesicular and pustular eruptions in adults with secondary syphilis have been published. We describe a patient with a bullous-pemphigoid-like eruption and a positive VDRL in whom treatment with a course of procaine penicillin resulted in rapid permanent resolution of the eruption.

Adult↗
PubMed1991

Leg ulcers in hereditary spherocytosis.

Refractory leg ulcers in two patients healed following splenectomy. Neither patient had the ethnic background or family history of haematological abnormalities to suggest a haemoglobinopathy.

Adult↗
PubMed1986

Morphological measurement of the SEP using a dynamic time warping algorithm.

A dynamic time warping technique was created to align the components of digitally high-pass (300 Hz-2500 Hz) filtered somatosensory evoked potentials evoked by median nerve stimulation recorded with a bipolar cephalic montage. A cost function was assigned related to the amount of warping necessary to match a standard wave derived from 24 normal subjects. Its value ranged from 0.525 to 2.456 (mean 1.305 +/- 0.501). This contrasted with a mean of 5.089 +/- 4.277 (range 0.701-13.972) derived from 25 patients with definite (n = 24) or possible (n = 1) multiple sclerosis chosen on the basis of having few or no clinical abnormalities at the time of testing. Fourteen (56%) of the patients had cost functions that were 3 or more S.D.s above the normal mean as compared to 3 (12%) having prolonged latency of the N19 peak. When used in combination, the cost function and latency yielded 60% abnormalities; 5 times higher than latency measurement alone.

Adult↗
PubMed1985

Assessment of skin ulcer healing capability by technetium-99m phosphate angiogram and blood-pool images.

The accuracy of radionuclide angiography and blood-pool imaging using [99mTc]-phosphate to assess skin ulcer perfusion as an indicator of healing capacity was determined in 50 studies performed on 45 patients with nonhealing ulcers of the lower extremities. Two nuclear medicine physicians without clinical bias, graded the perfusion of the ulcer on the images as normal, increased or reduced with respect to the opposite limb. Patients were followed closely with aggressive local wound care for at least 14 days. Of the 31 ulcers which healed, the radionuclide study correctly predicted 30; of the 19 ulcers which did not heal, 14 were correctly predicted. Eight patients had osteomyelitis; four of those healed and four did not. The radionuclide study predicted healing in seven. Excluding those patients with osteomyelitis, the sensitivity for the radionuclide angiogram and blood-pool image in predicting healing was 96%, specificity was 87%, and accuracy was 93%. This technique is a simple, reliable way to predict the microcirculatory adequacy for ulcer healing. Specificity is diminished in the presence of osteomyelitis.

Aged↗
PubMed1985

Value of a 24-hour image (four-phase bone scan) in assessing osteomyelitis in patients with peripheral vascular disease.

The delayed images of the four-phase 99mTc phosphonate bone scan are compared with the delayed images of the three-phase study in patients with diabetes mellitus and/or peripheral vascular disease and suspected osteomyelitis. Three-phase bone imaging includes an immediate postinjection radionuclide angiogram, a blood-pool image, and delayed static images to 7 hr. The four-phase study adds a 24-hr static image. The scan is positive for osteomyelitis if images show progressively increasing lesion to background activity ratios over time. The results of analyzing 21 three- and four-phase bone scans in 17 patients were correlated with clinical course, cultures, and/or x-rays, gallium scans, and CT scans. The accuracy of four-phase bone imaging for diagnosing osteomyelitis was 85%; for three phase, 80%. Sensitivity for four phase was 80%; specificity was 87%. Sensitivity for three phase was 100%; specificity was 73%. Since overall accuracy of the four-phase study is slightly better than three phase, in these patients with diabetes mellitus and/or peripheral vascular disease, the addition of a 24-hr image, creating a four-phase bone scan, is recommended.

Diabetic Angiopathies↗
PubMed1984

Questions regarding the sequential neural generator theory of the somatosensory evoked potential raised by digital filtering.

Digital bandpass filtering (300-2500 Hz) designed for zero phase shift was applied to somato-sensory evoked potentials recorded with cephalic bipolar montages. Four consistent negative and corresponding positive peaks with latencies of about 16, 18, 19, and 20 msec were elicited with median nerve stimulation. Peroneal nerve stimulation also elicited 4 reproducible negative-positive peaks having latencies of about 24, 26, 28, and 30 msec. Interpeak latencies measured 1.3 +/- 0.2 msec and 1.8 +/- 0.25 msec for median and peroneal elicited SEPs respectively. Because cephalic bipolar recordings cancel most far-field potentials, multiple generators cannot account for all the additional components seen. It is hypothesized that some of the high frequency components recorded are due to activity in recurrent intrathalamic neuronal networks.

Adult↗
PubMed1983

Inhalation exposure of lead in brass foundry workers: the evaluation of the effectiveness of a powered air-purifying respirator and engineering controls.

The protection that a powered air-purifying respirator afforded to ladle and furnace attendants who were exposed to lead, copper and zinc fumes in a brass foundry was found by measuring metal levels at the lapel and at nose level inside the respirator. Respirator fit was evaluated by use of a hot-wire anemometer at the face/Tyvek seal interfaces, and at the exit of the respirator. Effective protection factors for lead ranged from 1.05 to 67. Ergonomic factors and engineering controls are also discussed.

Air Pollutants, Occupational↗