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Biomedical subjects

R M Olson

Publications and source records attributed to R M Olson.

At least 37 records · Page 2Linked to original sources
PubMed1981

Distribution of cytokinin-active nucleosides in isoaccepting transfer ribonucleic acids from Agrobacterium tumefaciens.

The cytokinin-active isoprenoid nucleosides of Agrobacterium tumefaciens transfer ribonucleic acid were identified by high-pressure liquid chromatography, permethylation, and mass spectroscopy. Besides the expected 6-[(3-methylbut-2-enyl)amino]-9-(beta-D-ribofuranosyl)purine (i6A) and its 2-methylthio derivative (ms2i6A), substantial amounts of cis- and trans-ribosylzeatin (io6A) and cis-2-(methylthio)ribosylzeatin (c-ms2io6A) were present. These hydroxylated side chain derivatives are normally characteristic of plant tRNA. Fractionation of the total bacterial tRNA on BD-cellulose and RPC-5 allowed isolation of purified iso-accepting species whose cytokinin nucleoside contents were then determined. Distribution of the isoprenoid nucleosides among the U-group tRNA species was not uniform. cis-Ribosylzeatin was found almost exclusively in one tRNASer while ms2io6A was found predominantly in tRNAPhe, tRNASer, and tRNATyr. Not all cytokinin-active species were found in every member of the U-group tRNAs. The only species present in tRNATrp was i6A; it contained no zeatin derivatives. The hydroxylation and methylthiolation processes appear to be highly specific and dependent upon tRNA structure or sequence.

Amino Acyl-tRNA Synthetases↗
PubMed1981

Regional lymph node management and outcome in 100 patients with head and neck melanoma.

One hundred patients with invasive melanoma of the head and neck were treated by one surgeon from 1970 to 1978. Lymph node dissections were performed in 77 patients for palpable adenopathy, local recurrence, or tumor thickness greater than 0.75 mm when measured by micrometry. No patient whose lesion was less than 1.0 mm thick had a local recurrence or died as a result of melanoma. Patients who underwent elective lymph node dissection with findings of up to two positive nodes had a 53 to 56 percent 5 year survival rate, while those with three or more nodes had a poor prognosis (15 percent 5 year survival rate). The patterns of recurrence showed that relapse after nodal dissection usually presented with systemic metastases. The data support a therapeutic scheme based on 2 to 5 cm wide excision alone for lesions less than 0.75 mm in thickness and elective nodal dissection for specific indications.

Head and Neck Neoplasms↗
PubMed1981

Analysis of recurrence patterns following curative resection for carcinoma of the colon and rectum.

The records of 525 patients with adenocarcinoma of the colon and rectum were reviewed. Two hundred and eighty-five patients were evaluable following complete curative resections. These patients were evaluated for patterns of recurrence. The over-all recurrence rate was 78 of 285, 27 per cent. The over-all recurrence rate by site was 24.0, 10.0, 11.5 and 35.0 per cent for the right, transverse and left colon, the sigmoid and the rectum, respectively. The over-all failure rate by stage was 13 per cent for Stage A, 11 per cent for Stage B1, 32 per cent for Stage C1, 37 per cent for Stage B2-3 and 56 per cent for Stage C2-3. The over-all failure rate as related to Stages A, B1, C1, B2-3 and C2-3 and to site of primary disease was: right--zero, 9, 33, 28 and 43 per cent, sigmoid--11, 15, 40, 52 and 62 per cent; rectal group--29, 14, 40, 46 and 60 per cent as related to respective stages. There was one failure among the five patients with Stage B2-3 disease in the transverse group and two failures among the nine patients with Stage B2-3 and one failure in the one patient with Stage C2-3 within the left colon group. Individual types of failure were compiled. Lesions involving the rectum and sigmoid colon had a significant local-regional component to relapse. Tumors of the right, transverse and the left colon had a significant distant recurrence rate. Factors of primary site, age at diagnosis, extent of disease and histology were reviewed as to the over-all recurrence and specific failure sites. From this analysis, a schema involving patterns of failure as related to primary site and stage within the colon, rectum and sigmoid were developed.

Adenocarcinoma↗
PubMed1980

Patterns of recurrence following curative resection of adenocarcinoma of the colon and rectum.

This study explores the patterns of recurrence after "curative" operation for colorectal cancer. For an 11-year period, 1960-1971, 281 evaluable patients were resected at the Peter Bent Brigham Hospital. Crude five-year survival in these patients was 49%, but only 10% of those with recurrence lived five years. A total of 69 patients relapsed during their lifetime and 34 additional patients were found to have metastases at death. The initial site of metastases were regional in 23 patients (33%) and distant in 32 (46%). Simultaneous regional and distant metastases were found in 13 (19%) for a total of 65% of patients having initial distant metastases. Approximate recurrence rates by site were: 30% for sigmoid and rectum, 20% for right colon, and 10% for transverse and left colon. Tumor size was a significant determinant of recurrence but did not select for regional or distant sites. Recurrence by Astler-Coller modification of the Dukes-Kirklin classification revealed 10% for A + B1, 33% for B2, 35% for C1, and 50% for C2. More than half of the patients with distant metastases (18/32) had solely hepatic metastases yet the total incidence of liver metastases as the initial site was only 8% of the total. In general, the site of the primary cancer was the most important determinant of the type of recurrence; the stage and site of the primary tumor were most predictive for eventual relapse.

Adenocarcinoma↗
PubMed1980

Aplasia cutis congenita.

Aplasia cutis congenita is an uncommon condition; fewer than 300 cases have been reported in the literature. Usually, the condition occurs as a focal scalp ulcer, but it may involve the full thickness of the skull or other areas of the body. Most lesions require coverage with a scalp flap, though only observation or split-thickness skin grafts may be adequate for smaller lesions. Four cases have been presented, representing a spectrum of therapeutic requirements from simple observation to emergency intervention to control life-threatening hemorrhage. The case of aplasia cutis congenita of the upper arm may represent a persistence of prenatal focal ischemia that has proved to be resistant to numerous attempts of split-thickness skin grafting.

Arm↗
PubMed1978

Effects of using long breathing hoses upon mask pressure.

Effects of using oxygen breathing hoses from 0.9 to 8.2 m (3 to 27 ft) long and mask fit upon mask pressure during 0.75 to 12-s decompressions from 2,438 m (8,000 ft) to either 6,096, 10,668, or 15,240 m (20,000, 35,000 or 50,000 ft) were determined. Peak mask pressures and duration of high mask pressure were related to mask fit, mask and hose stretch compliance, pressure differential, decompression rate, and other factors, with mask pressure increasing with hose length. Peak mask pressures frequently exceeded 80 mm Hg, a high pressure associated with increased incidence of pulmonary damage. Cargo-type aircraft, however, have sufficiently large volumes so that they will not decompress rapidly enough to have high mask pressure, even with an 8.2-m long hose. Long breathing hoses should not be used in smaller aircraft since small cabin volume will result in rapid decompression rates and high mask pressure. Above a flight altitude of 2,438 m, oxygen should always be breathed if hoses longer than 2.9 m (9 ft) are used. This would help prevent hypoxia, associated with the need to deplete air in the hose before oxygen is breathed, should cabin pressure be lost at a high altitude. The fastest decompression rates compatible with preventing mask pressures from exceding 80 mm Hg during decompressions to different altitudes with different length breathing hoses are given.

Aerospace Medicine↗
PubMed1978

Effects of long-hose breathing.

The need for aircrew members to use long breathing hoses between regulator and mask arises in the design of new transport aircraft and in several cargo operations requiring an open rear door. In this study, induced work of breathing through long hoses, the resulting changes in oxygen consumption, and comfort were studied in relation to altitude, hose length, and exercise level. Conclusions were that, above 18,000 ft (5.5 km), a 30-ft (9.1-m) hose is acceptable for all reasonable work levels; for altitudes between 13,000 and 18,000 ft (4.0 and 5.5 km), the hose length should preferably be 18 ft (5.5m), and at altitudes below 13,000 ft (4.0 km), hose length should be limited to 12 ft (3.6). Moreover, at ground level, the hose length should be limited to 6 ft (1.8 m) for all but sedentary activity. Should the potential for rapid decompression exist, at any altitude, volume considerations limit hose length to 18 ft (5.5 m) since larger hoses possess excessive regulator-to-mask dead space.

Adult↗
PubMed1976

Economical oxygen-delivery system.

The conservation of aircraft oxygen supplies is becoming of considerable interest to the Air Force. Onboard oxygen-generating systems are being developed which could support an aircrew if oxygen produced by these systems were used conservatively. These experiments studied the conservation potential of a rebreather bag placed in a vented container near the regulator in an oxygen-delivery system. The bag's volume was close to that of the subject's physiologic dead space. When the subject exhaled, oxygen in the mouth, trachea, and mask dead space went to the rebreather bag, to be rebreathed with the next breath. The CO2-contaminated oxygen from the alveoli was vented to the cabin. The dead-space oxygen could be separated from contaminated oxygen because dead-space air is exhaled first with each breath. When the rebreather-bag volume matched the subject's physiologic dead space so that no CO2 accumulated, a 30% oxygen savings was realized. When the bag was large enough to realize a 50% savings, CO2 accumulation was only 2%.

Aviation↗
PubMed1976

Intravascular bubbles associated with intravenous injections and altitude.

Ultrasonically detected microbubbles were more abundant in the pulmonary artery of dogs intravenously injected with 10 ml of saline than in the same noninjected controls during 10,000 ft (3,048 m), 20,000 ft (6,096 m), and 40,000 ft (12,192 m) exposures. Continuous intravenous (i.v.) drip infusions also introduced many small bubbles. Since they may serve as "nuclei" for visible intravascular bubble formation, are sometimes associated with decompression sickness, and are additionally considered undesirable, it would appear prudent to minimize i.v. injections immediately before flights. However, a 10-min delay before ascent will reduce their number and a 60-min delay will insure their almost complete absence. Also, slow ascent, a 1-h denitrogenation time, or use of a degassed solution will help reduce their total number.

Aerospace Medicine↗
PubMed1975

Blood flow during 2-Torr exposures at different decompression rates.

Central and peripheral blood flow of denitrogenated dogs, measured in the femoral artery and aorta, declined rapidly and ceased within mean times of 28, 35, 70, or 90 s after 1-, 10-, 30-, or 60-s decompressions from 258 Torr to 2 Torr, respectively. Neither arterial nor venous hypoxemia was seen after 1-s decompressions since the hypoxic blood did not reach the aorta. In contrast, arterial and venous O2 saturation levels dropped as low as 12 or 6% following 10- to 60-s decompressions since circulation continued. A severe and transient decerebratelike rigidity and subsequent temporary flaccid paralysis of the hind legs was seen during recovery from decompressions slower than 1 s, whereas only a mild temporary flaccid paralysis was frequently present after 1-s decompression. The more severe responses following 10- to 60-s decompressions are associated with the greater hypoxemia after slow decompressions, indicating tissue hypoxia is more severe when decompression rate is slow.

Animals↗