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Biomedical subjects

C Connelly

Publications and source records attributed to C Connelly.

27 records · Page 2Linked to original sources
PubMed1986

Optimization of culture conditions for the maintenance of Onchocerca gutturosa adult worms in vitro.

A series of experiments examined the effects of various media, serum supplements, gas phases and the incorporation of mammalian cell feeder layers on the survival of Onchocerca gutturosa adult worms in vitro. The survival of male worms was poor in all media tested that were not supplemented with inactivated foetal calf serum (IFCS), with improved but variable survival in media supplemented with 10-30% IFCS. Using a cell-free system in an atmosphere of 5% CO2 in air, good results were obtained in medium NCTC 135 + 10% IFCS (median survival time 39 days, range 25-41). Marginally better survival was obtained with the same medium in an atmosphere of 95% N2/5% CO2 (median 45 days, range 25-56) and with a 1:1 mixture of media NCTC 135 and IMDM + 10% IFCS (median 38 days, range 38-51). Survival was enhanced in culture systems which incorporated bovine kidney (MDBK) cells, bovine trachea (EBTR) cells and monkey kidney (LLCMK2) cells. Exceptionally long survival was obtained using medium MEM + 10% IFCS + LLCMK2 cells under a gas phase of 5% CO2 in air, in which male worms survived from approximately 6 to over 7 months. Under similar conditions, female worms were also maintained for periods of up to 6 months and 5 out of 18 specimens released microfilariae into the culture system. The long-term culture described in this study will be useful for basic biochemical, chemotherapeutic and immunological studies in vitro.

Animals↗
PubMed1984

Pathogenesis of meningitis: experimental studies on the molecular basis of Haemophilus influenzae infection.

The successful development and implementation of rational strategies for the prevention of bacterial meningitis should be facilitated by acquiring a more detailed knowledge of its pathophysiology. We have used a biologically relevant rat model of meningitis in conjunction with classical microbial genetics and recombinant DNA technology to investigate the molecular basis of Haemophilus influenzae pathogenicity. These studies aim to define how specific bacterial genes mediate the potential of H. influenzae to colonize the nasopharynx, disseminate within the blood stream and invade the central nervous system. By identifying the state or stages in the pathogenic sequence for which the determinant is critical, this approach should also provide insight into the relevant host defense mechanisms which determine resistance or susceptibility. An understanding of the genetic basis of H. influenzae pathogenicity may develop basic knowledge relevant to the treatment and prevention of bacterial meningitis.

Animals↗
PubMed1984

Failure of nifedipine and reperfusion to reduce infarct size relative to region at risk as measured by NADH fluorophotography.

In this report we describe a new technique for the measurement of region at risk after coronary artery ligation in the rabbit by NADH fluorophotography. We also describe the application of this technique to a study of nifedipine combined with reperfusion in experimental myocardial infarction. In 16 untreated rabbits the epicardial surface area of NADH fluorescence immediately after coronary ligation correlated with infarct size at 24 hr after coronary occlusion, as measured by nitro blue tetrazolium staining (r = .84, p less than .001). In 24 rabbits we studied the effect of nifedipine administered immediately after coronary ligation and combined with reperfusion at 1 hr after occlusion. Nifedipine had no significant effect on region at risk or infarct size.

Animals↗
PubMed1984

Cloning of chromosomal DNA from Haemophilus influenzae. Its use for studying the expression of type b capsule and virulence.

Haemophilus influenzae may make any one of six chemically distinct capsular polysaccharides, but only strains of capsular serotype b commonly cause systemic infection (e.g., meningitis) in humans. Molecular cloning of DNA was used to investigate the expression of type b capsule and its association with H. influenzae virulence. A virulent H. influenzae type b strain was used to construct a lambda library of chromosomal DNA in Charon 4. Two independently isolated recombinant phage were isolated from the library and were found to possess DNA necessary for expression of type b capsule. Using a well-characterized rat model of H. influenzae systemic infection, we showed that type b transformants elicited by the cloned DNA were pathogenic, causing bacteremia and meningitis, whereas the untransformed capsule-deficient H. influenzae organisms were not. A 4.4-kb EcoRI fragment, common to both DNA clones, was used to characterize clinical isolates representing all six encapsulated serotypes as well as several capsule-deficient H. influenzae by Southern hybridization analysis. The probe hybridized to an identical sized (4.4 kb) fragment of EcoRI-digested chromosomal DNA from eight independently isolated type b strains. Single bands of homology to the probe were also found in EcoRI fragments of chromosomal DNA obtained from 33 encapsulated, nontype b H. influenzae. However, the size of these EcoRI fragments proved to be characteristic for each of the different capsular serotypes. These studies provide a basis for pursuing the molecular analysis of the epidemiology and virulence of pathogenic H. influenzae.

Animals↗
PubMed1982

Movement of necrotic wavefront after coronary artery occlusion in rabbit.

Movement of the necrotic wavefront after coronary artery occlusion (CAO) was defined in rabbits by comparing transient CAO (15, 30, or 60 min) and reperfusion to permanent CAO (n = 5-9/group). At 24 h after CAO the area of necrosis was determined by nitro-blue tetrazolium staining, and the transmural and circumferential extent of necrosis was evaluated at four levels from ligation to apex. Infarct size after permanent CAO for 24 h was 27 +/- 2 (SE) % of the left ventricle. Reperfusion at 60, 30, or 15 min after CAO reduced the infarct size to 24 +/- 3 (P = NS vs. 24 h), 14 +/- 2, and 8 +/- 1% (P less than 0.05 vs. 60 min), respectively. Reperfusion at 15 and 30 min after CAO decreased transmural extent by 49 and 38% (P less than 0.001 vs. 24 h), whereas the circumferential extent was reduced by only 10 and 12%, respectively (P = NS). After 60 min of CAO, reperfusion did not significantly reduce either transmural or circumferential necrosis. Thus early reperfusion reduced infarct size by converting potentially transmural infarcts into subendocardial infarcts but did not significantly reduce the lateral or circumferential extent of necrosis.

Animals↗
PubMed1980

Auditory brainstem responses in perinatal asphyxia.

Averaged auditory brainstem responses (ABR) elicited by unfiltered clicks were recorded from 14 asphyxiated neonates with clinical evidence of CNS suppression at 3-17 days of age, and from a group of healthy neonates matched in gestation period and weight. Statistically significant differences were found between the two groups in several ABR parameters and characteristics. In general, longer ABR component latencies and interwave intervals were the rule in the asphyxiated group. Short-term follow-up of the asphyxiated infants suggested that the ABR is sensitive to recovery trends from hypoxic encephalopathy. The results of a 6-month follow-up are also summarized. The results are discussed with regard to the histopathological and experimental information available from current literature.

Asphyxia Neonatorum↗
PubMedDate not supplied

Onchocerca gutturosa and O. volvulus: studies on the viability and drug responses of cryopreserved adult worms in vitro.

The viability and drug responses of cryopreserved adult Onchocerca have been examined in vitro. Male worms were cryopreserved in liquid nitrogen (-196 degrees C) using ethanediol as a cryoprotectant in a 2-step incubation procedure. After thawing, 85-90% of O. gutturosa males were normally motile. These motile worms were evaluated for viability using 4 measurements (long-term motility/survival in culture; [U-14C]adenine uptake and leakage; glucose utilization; MTT-formazan colorimetry) and were no different from unfrozen controls. Subsequent experiments demonstrated that the motility responses of cryopreserved worms exposed to the antifilarial drugs ivermectin, CGP 6140 and levamisole were virtually identical to unfrozen controls. Some success was also obtained with this technique in cryopreserving O. volvulus males, with 2 thawed specimens surviving in culture for 93 and 106 d respectively. Following collagenase isolation, female worms were cryopreserved in medium +10% serum without protectant at -79 degrees C. A batch of 8 female O. gutturosa were all motile when thawed 14 d later, with a mean survival time (based on 5 specimens) of 71 d (range 60-90). However, a batch of worms transferred from -79 degrees C to -196 degrees C were badly damaged when thawed. Female O. volvulus were cryopreserved at -79 degrees C in Guatemala and sent by air freight on solid CO2 to the UK. Most specimens were active when thawed. Survival of motile specimens ranged from 7 to 272 d in culture. It is concluded that these techniques are of practical value for the storage and transportation of adult Onchocerca.

Adenine↗