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Biomedical subjects

S Kelly

Publications and source records attributed to S Kelly.

At least 199 records · Page 11Linked to original sources
PubMed1985

Purification of the HhaII restriction endonuclease from an overproducer Escherichia coli clone.

An Escherichia coli K12 strain carrying the HhaII methylase and restriction genes on two separate compatible plasmids, pSK5 and pSK7, is used to overproduce the restriction endonuclease. Plasmid pSK5 expresses the methylase gene constitutively from its chloramphenicol resistance gene promoter, and plasmid pSK7 expresses the restriction endonuclease under control of the lacUV5 promoter. Induction of the two-plasmid clone with 1 mM isopropyl-1-thio-beta-D-galactopyranoside results in a 15-fold increase in HhaII endonuclease activity. The enzyme has been purified to apparent homogeneity. It migrates as a 23-kilodalton polypeptide on denaturing sodium dodecyl sulfate-polyacrylamide electrophoretic gels and as a 52-kilo-dalton native protein dimer on a high pressure liquid chromatography sizing column.

Chloramphenicol↗
PubMed1985

Alteration of airway reactivity by mucus.

In 11 beagles with permanent tracheostomies we investigated whether mucus hypersecretion alters airway reactivity to inhaled aerosols. Mucus was collected from the dogs while awake by resting a cytology brush on the lower tracheal mucosa; the mucus collection rate was used as an index of mucus flux. Mucus linear velocity was determined under light sedation by bronchoscopically observing the rate of particle clearance in the trachea. Mucus depth was then computed from the flux and velocity. On a separate occasion, under pentobarbital anesthesia, methacholine aerosols (1 min duration) were given at 10 min intervals in doubling doses up to at least 2 mg/ml. Pulmonary resistance RL was determined prior to and 2 min after each dose. After a 1 h pause, methacholine was infused at a constant rate of 40 micrograms X kg-1 X min-1 for 10 min. This dose produced a plateau in RL after approximately 3 min; the mean rise in RL was similar to that achieved with the 2 mg/ml aerosol. The infusion response Rinf was defined as the change in RL 4-5 min post infusion; the aerosol response Raer was defined as the change in RL 2 min post 2 mg/ml aerosol. There was no significant correlation between Rinf and Raer, nor between either Rinf or Raer and mucus flux. There was, however, a strong positive association between Rinf/Raer and mucus flux and a similar positive association between Rinf/Raer and mucus depth. These associations indicate that dogs with elevated secretion levels are relatively unresponsive to aerosolized as opposed to infused methacholine. Thus, to the extent that infusion reactivity reflects innate airway reactivity, the reactivity to inhaled aerosol may underestimate the true value when mucus hypersecretion occurs.

Aerosols↗
PubMed1985

Mechanics of intercostal space and actions of external and internal intercostal muscles.

It is conventionally considered that because of their fiber orientations, the external intercostal muscles elevate the ribs, whereas the internal interosseous intercostals lower the ribs. The mechanical action of the intercostal muscles, however, has never been studied directly, and the electromyographic observations supporting this conventional thinking must be interpreted with caution. In the present studies, the external and internal interosseous intercostal muscles have been separately stimulated in different interspaces at, above, and below end-expiratory rib cage volume in anesthetized dogs. The axial (cephalo-caudal) displacements of the ribs were measured using linear displacement transducers. The results indicate that when contracting in a single interspace and other muscles are relaxed, both the external and internal intercostals have a net rib elevating action at end-expiratory rib cage volume. This action increases as rib cage volume decreases, but it progressively decreases as rib cage volume increases such that at high rib cage volumes, both the external and internal intercostals lower the ribs. Stimulating the intercostal muscles in three adjacent intercostal spaces simultaneously produced similar directional rib motion results. We conclude that (a) in contrast with the conventional thinking, the external and internal interosseous intercostals acting alone have by and large a similar effect on the ribs into which they insert; (b) this effect is very much dependent on rib cage (lung) volume; and (c) intercostal muscle action is primarily determined by the resistance of the upper ribs to caudad displacement relative to the resistance of the lower ribs to cephalad displacement. The lateral intercostals, however, might be more involved in postural movements than in respiration. Their primary involvement in rotations of the trunk might account for the presence of two differently oriented muscle layers between the ribs.

Animals↗
PubMed1985

The cellular basis of haemoglobin switching: further studies of fetal-to-adult haemopoietic cell transplantation.

The switch from fetal to adult hemoglobin synthesis appears to be due to a change in gene expression within the same hemopoietic lineage. The timing of this change looks to be largely determined by the gestational age of the hemopoietic cells, consistent with their containing an intrinsic developmental clock. Precocious switching of fetal cells in an adult environment could reflect an interaction of this clock with external factors or may result from an acceleration of the clock under the extreme experimental conditions, possibly associated with an increased rate of stem cell division.

Animals↗
PubMed1985

Enteroscopy: a method for detection of small bowel tumors.

Small bowel neoplasms are difficult to identify. Conventional roentgenographic methods may report false-negative results in 23-44% of cases. We describe a symptomatic patient with a jejunal leiomyoma detected by enteroscopy after radiographic evaluation was equivocal. Enteroscopy can be an effective diagnostic modality in selected patients with small bowel tumors.

Aged↗
PubMed1984

Prospective study of tympanosclerosis developing after grommet insertion.

Grommets have been used as a treatment for middle-ear effusions since their introduction by Armstrong in 1954. However, it is now accepted that the presence of a grommet in a tympanic membrane is associated with the development of tympanosclerosis in that membrane. Furthermore, it has been shown that this is a progressive phenomenon and that the incidence increases with time to as much as 65 per cent at 3 to 4 years after grommet insertion (Mawson and Fagan, 1972; Tos and Poulsen, 1976). Initially it was suggested that the development of tympanosclerosis might be due to the middle ear disease rather than to the grommet (McKinnon, 1971). However, most recent studies have found that, in bilateral cases of effusion, tympanosclerosis develops more frequently in ears with a grommet than in those without (Brown, Richards and Ambegaokar, 1978; Lildholt, 1979). This prospective study was designed to show the development of tympanosclerosis in the tympanic membrane of children treated for bilateral middle-ear effusions and to elicit any factors from the clinical history and operative technique which might be associated with the pathogenesis of the complication.

Child↗
PubMed1984

Action of neck accessory muscles on rib cage in dogs.

To investigate the action of the neck accessory muscles on the rib cage, we stimulated the sternocleidomastoid and the scalenus muscles separately in supine anesthetized dogs. Hooks screwed into the sternum and ribs were used to measure their axial displacements and the changes in anteroposterior (AP) and transverse (T) diameters of the rib cage. We found that the sternocleidomastoid and scalenus muscles, when they contract alone, cause a large axial displacement of the sternum and the ribs in a cephalad direction and expand the rib cage along both its AP and T diameters. Opening the abdomen increased the cephalad displacement of the ribs and the expansion of the lower rib cage, particularly along its T diameter, but reduced the increase in lung volume. These experiments indicate 1) that the action of the sternocleidomastoid and scalenus muscles on the rib cage is essentially the consequence of a rotation of the ribs' neck axes, resulting from the cephalad displacement of the ribs, and 2) that the fall in abdominal pressure, almost certainly by acting through the zone of apposition of the diaphragm to the rib cage, has a deflationary action on the lower rib cage, more markedly so on its lateral than its anterior wall. The experiments also suggest that the fall in abdominal pressure prevents the diaphragm from moving cephalad and aids the neck accessory muscles in inflating the lungs.

Abdomen↗
PubMed1984

Salutary effect of fall in abdominal pressure during diaphragm paralysis.

To examine the mechanical effects of the fall in abdominal pressure (Pab) that occurs during inspiration in diaphragmatic paralysis, we studied lung inflation and rib cage expansion before and after the abdomen was opened in nine spontaneously breathing dogs with bilateral phrenicotomy . We measured Pab, tidal volume, and parasternal electromyographic (EMG) activity during quiet breathing and CO2-induced hyperpnea. In six dogs, we also measured changes in anteroposterior and transverse rib cage diameters, the resting length of the parasternal intercostal muscles, and the amount of shortening of these muscles during inspiration. Opening the abdomen caused a marked reduction in the fall in Pab during inspiration and invariably resulted in a decrease in tidal volume (mean decrease, 13%), which contrasted with marked increases in inspiratory rib cage expansion and in the amount of parasternal intercostal shortening. The procedure, however, did not affect the resting length or inspiratory EMG activity of the parasternals . These findings indicate that although the fall in Pab, which occurs during inspiration in diaphragmatic paralysis, causes paradoxical inward displacement of the ventral abdominal wall, it has a salutary effect on tidal volume. This phenomenon is probably due to the fact that the diaphragm is part of the abdominal wall.

Abdominal Muscles↗
PubMed1984

Mechanical arrangement of costal and crural diaphragms in dogs.

To assess the mechanical arrangement of the costal and crural parts of the diaphragm, we studied changes in diaphragmatic length with piezoelectric crystals in 17 supine anesthetized dogs. During control resting inspiration, the crural part usually shortened more and earlier than the costal part. After phrenicotomy, the crural part always lengthened during inspiration, whereas the costal part shortened or lengthened. These interanimal differences disappeared after opening of the abdomen; the costal part then always lengthened during inspiration. During stimulation of one part, the relaxed nonstimulated part always lengthened. However, when compared with the relationship between length and transdiaphragmatic pressure (Pdi) obtained during passive deflation, the lengthening of the relaxed part during stimulation of either part was small. This difference between predicted and measured Pdi-length relationship decreased in magnitude as lung volume increased above functional residual capacity (FRC) and increased as residual volume was approached. These results indicate that 1) even during quiet breathing the diaphragm in the dog is not a single functional entity; 2) at FRC the costal and crural portions of the diaphragm behave as if they were mechanically arranged partly in parallel and partly in series; and 3) they gradually move into a pure mechanical series arrangement as lung volume increases.

Animals↗
PubMed1984

Regional differences in abdominal pressure swings in dogs.

The pressure swings under the costal (Pcos) and crural diaphragms (Pcru) and between the intestinal loops (Pint) were compared with the swings in gastric pressure (Pga) in 13 supine anesthetized dogs. Pcos, Pcru, and Pint were measured with air-filled latex balloons in eight dogs and saline-filled catheters in five. Pga was measured with an air-filled balloon in all dogs. During quiet breathing differences were often present, the directions of which were variable from animal to animal. During mechanical ventilation, all pressures increased, but both Pcos and Pcru increased more than Pga, whereas only a small change was observed in Pint. During bilateral stimulation of the costal diaphragm, Pcos invariably increased more than Pga and Pint, whereas almost no change was observed in Pcru. During bilateral stimulation of the crural diaphragm, Pcru invariably increased more than Pga, Pint, and Pcos. During abdominal muscle stimulation as during external abdominal compression, Pint always increased more than Pcos and Pcru. During lower rib cage compression, Pga, Pcos, and Pcru increased more than Pint. During sternocleidomastoid stimulation, all pressure swings were negative, but the change in Pint was always smaller than in Pcos, Pcru, or Pga. Inhomogeneities observed with balloons and saline-filled catheters were similar. After the abdomen was filled with 2 liters of saline all pressure swings became much more homogeneous.

Abdomen↗
PubMed1984

Prospective evaluation of metabolic bone disease after jejunoileal bypass.

Twenty-eight patients undergoing jejunoileal bypass for morbid obesity were studied prospectively for alterations in mineral metabolism and the development of metabolic bone disease. Eleven additional patients were examined for long-term complications. Serum 25-hydroxyvitamin D and fractional calcium absorption were depressed during the first 2 yr after bypass but normalized after this period. Serum parathormone remained normal. Mild osteomalacia was identified in 12% of subjects by histomorphometric analysis of undecalcified biopsy specimens. Osteomalacia was asymptomatic and could not be reliably diagnosed by noninvasive tests. Repeat biopsies demonstrated histologic improvement in 2 individuals followed serially. Improvement was not clearly related to vitamin D therapy. Abnormalities in mineral appositional rates and mineral maturation were identified in several additional patients. Studies in the long-term group did not indicate inexorable progression of metabolic bone disease. Although intestinal bypass produced several abnormalities in mineral metabolism during the first 2 yr after surgery, a trend toward normalization was evident after the period, possibly related to adaptive responses in the intestine.

Absorption↗
PubMed1983

Mechanical action of the intercostal muscles on the ribs.

The external and internal interosseous intercostal muscles were separately stimulated at end-expiratory lung volume in anesthetized dogs. These muscles were all found to elevate the ribs into which they insert. By attaching weights to the ribs, it was determined that the nonlinear compliance of the ribs was responsible for this phenomenon.

Animals↗
PubMed1983

The nucleotide sequence of the HhaII restriction and modification genes from Haemophilus haemolyticus.

We have determined the nucleotide sequence of a cloned 1710-bp segment of Haemophilus haemolyticus DNA which contains the HhaII restriction (r) and modification (m) genes. The m gene is 513 bp in length and the rgene is 681 bp in length. Both are in the same reading frame, being separated by a 21-bp region. A ribosome-binding site is identified in front of each gene, but no Haemophilus promoter is apparent on the cloned fragment. Transcription originates from a plasmid promotor and proceeds in the direction m to r.

Bacterial Proteins↗
PubMed1983

Golgi membranes contain an electrogenic H+ pump in parallel to a chloride conductance.

Rat liver Golgi vesicles were isolated by differential and density gradient centrifugation. A fraction enriched in galactosyl transferase and depleted in plasma membrane, mitochondrial, endoplasmic reticulum, and lysosomal markers was found to contain an ATP-dependent H+ pump. This proton pump was not inhibited by oligomycin but was sensitive to N-ethyl maleimide, which distinguishes it from the F0-F1 ATPase of mitochondria. GTP did not induce transport, unlike the lysosomal H+ pump. The pump was not dependent on the presence of potassium nor was it inhibited by vanadate, two of the characteristics of the gastric H+ ATPase. Addition of ATP generated a membrane potential that drove chloride uptake into the vesicles, suggesting that Golgi membranes contain a chloride conductance in parallel to an electrogenic proton pump. These results demonstrate that Golgi vesicles can form a pH difference and a membrane potential through the action of an electrogenic proton translocating ATPase.

Adenosine Triphosphatases↗
PubMed1983

Eye injuries in organised sport in a rural area.

Eye injuries in sport are a continuing preventable problem. An investigation into sport injuries in rural Ireland shows hurling to be the most dangerous pastime, and this is compared and contrasted with other local games. Forty-five consecutive injuries sustained in organised sport requiring admission to hospital over a 4-year period were studied. 40% were due to hurling. Over three-quarters of the 45 patients recovered 6/6 vision or better. The costs to the community of such eye injuries are discussed.

Adolescent↗