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Biomedical subjects

C Comstock

Publications and source records attributed to C Comstock.

7 recordsLinked to original sources
PubMed1990

Coronary heart disease in Massachusetts: the years of change (1980-1984).

During this decade, diagnosis and treatment of coronary heart disease (CHD) have become far more aggressive and invasive than in prior decades. This study documents rates of hospitalization, use of various treatment options, a case fatality in the state of Massachusetts during 4 of the first 5 years of this decade (1980, 1982, 1983, and 1984). The data base was that of the Massachusetts Health Data Consortium (MHDC), covering all hospital discharges in the state, a total of 3.8 million discharge records for this period. Of these, about 190,000 (5%) fell into two active symptomatic categories of CHD: chronic active coronary disease (CACD) and acute myocardial infarction (AMI). Total hospitalization rate for these CHD categories increased by 17%; this was due both to an increased rate of hospital transfers (or readmissions) and to a larger cohort of patients under care. The case fatality rate for hospitalized CHD decreased approximately 16%, from 9.7% (1980) to 8.1% (1984). In CACD the frequency of coronary angiography (CA) rose; the use of percutaneous transluminal coronary angioplasty (PTCA) increased much faster than the rate of coronary artery bypass grafting (CABG), with a resultant increase in PTCA as a fraction of total interventions. Similar findings were recorded for AMI, but with much more marked changes, the total intervention rate increasing almost twenty-fold from 1980 to 1984. The statewide mortality rate for hospitalized CHD patients remained essentially unchanged at 71 to 74 hospital deaths per 100,000 population.

Angiography↗
PubMed1987

Ligand-receptor dynamics and signal amplification in the neutrophil.

Intact neutrophils appear to exhibit interconverting formyl peptide receptor states. The first may be active in transduction and has a dissociation half-time of less than 10 sec. The second appears to be inactive and has a dissociation half-time of approximately 2 min. Neutrophil signals and responses are transient following "pulse" stimulation (when the stimulus is presented and then rapidly removed). The responses decay to baseline following a latency period comparable to the lifetime of the activated receptor. These results are consistent with the notion of transient interconverting receptor states and are discussed in terms of the biochemistry and amplification of the cell activation pathways. We examined the effect of guanine nucleotides on ligand-receptor dynamics at 37 degrees C in neutrophils permeabilized with digitonin, using continuous fluorometric measurements. The permeabilized cells exhibit a single class of slowly-dissociating receptor with a half-time similar to the inactive state. When guanine nucleotide is added, the receptors dissociate with a half-time similar to the first state. The effect of guanine nucleotide is inhibited by Ca++ concentrations above 10 microM. When receptors in permeabilized cells are ADP-ribosylated in the presence of pertussis toxin, the rapidly dissociating state is detected. These results suggest that the dynamics of ligand-receptor interaction under physiological conditions are controlled by a pertussis-toxin-sensitive guanine-nucleotide-binding protein. Guanine nucleotide regulates interconverting states of the formyl peptide receptor and mimics the dynamic states of the receptor observed in the intact cell during stimulation. A model which accounts for these data is described.

Calcium↗
PubMed1985

Report on variation in rates of utilization of surgical services in the Commonwealth of Massachusetts.

This article presents an analysis of over 140,000 selected surgical procedures performed in Massachusetts in 1980, giving the per capita rates of 14 common procedures and of four less frequently performed procedures. The analysis defines 172 geographic areas for the commonly performed procedures and 45 for the less frequently performed procedures. Per capita surgical rates among the defined areas are significantly different from both a statistical and a clinical point of view. Twofold and threefold variations occur frequently across geographic areas. In certain areas, some surgical services appear to be provided at rates substantially different from the statewide rate. We discuss the importance of these data for physicians as well as the implications for the distribution and quality of clinical care and for containment of medical care costs.

Costs and Cost Analysis↗
PubMed1977

Percutaneous needle localisation of breast lesions prior to biopsy: analysis of failures.

Mammography can detect clinically occult breast cancer. But with minimal or no physical findings the lesion can be quite difficult for the surgeon to find within the recumbent breast at biopsy. Percutaneous needle localisation, the placement of a needle in or in the vicinity of such a clinically silent lesion, provides an internal landmark to assist the surgeon. Review of our experience of 90 procedures using this technique disclosed a success rate of approximately 90%. The biopsies diagnosed 14 cancers before local or distant metastasis could be found. The eleven of the fourteen who had axillary dissection were found to have negative nodes. Identifiable causes of failure were sought and discussed in the 7 documented failures. Faulty needle placement was judged noncontributory in all but one case. Needle movement between time of placement and time of biopsy could never be excluded and is in fact suspected in two failures. Immediate re-sampling, or larger initial specimens would have salvaged the procedure in most instances of failure. We feel poor communication and poor mutual understanding of the localization procedure to be the major contributing cause of failure. Even so, we have been able to use the technique with 90% success. The development of mammography brought with it the opportunity to detect small non-palpable carcinomas and the surgical problem of removing them at biopsy. While the suspect lesions identified by mammography are frequently benign, the cancers found are usually small and some only microscopic in size. The literature contains many descriptions of various techniques for localising such lesions prior to biopsy. We are reporting our experience with percutaneous needle localisation. To our knowledge, we have the distinction of being the first to report difficulty with a localisation technique and will analyse possible reasons. Some of the problems are common to all the localisation techniques.

Adult↗
PubMed1977

A simple device for dependent compression mammography.

The authors describe an inexpensive device which displaces the dependent breast from the chest wall for optimum and uniform compression of breast tissue during mammography. Exposure is reduced, detail is enhanced, and superimposed structures are spread out. The filming time is about five minutes, and repeat or additional views are rarely necessary. The authors feel that by using this device, they have not missed any posterior lesions in more than 10 years of use. Even dense breasts are adequately visualized with this technique.

Female↗
PubMed1975

Roentgenology of sporotrichosis.

Localized cutaneous as well as unifocal and multifocal systemic sporotrichosis may all produce roentgenographic findings. Localized cutaneous nodules may occasionally extend to the bone below producing a locally erosive lesion similar to those more commonly found in blastomycosis. More frequently, sporotrichosis involves the joints, either alone or with accompanying skin nodules. The joint changes are those of a pyogenic arthritis of the knees, elbows, hands, or feet which is difficult to distinguish from pyarthrosis produced by other organisms. The pulmonary findings depend upon whether or not the lung is the only site of infection. If there are no other areas of involvement, the pulmonary findings may be indistinguishable from those of secondary tuberculosis. However, if the skin on joints are also involved, small nodules appear and apparently do not proceed to cavitation.

Adult↗