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Biomedical subjects

M B Cole

Publications and source records attributed to M B Cole.

At least 19 recordsLinked to original sources
PubMed1992

TPK gene products mediate cAMP-independent thermotolerance in Saccharomyces cerevisiae.

Incubation of Saccharomyces cerevisiae with the plant cytokinin N6-(delta 2-isopentenyl)adenine (2iP) resulted in an induction of thermotolerance similar to that induced by sublethal temperatures. Intracellular cAMP levels did not change significantly either during incubation at a sublethal temperature or in the presence of 2iP or ethanol. This suggested that stress-induced thermotolerance is triggered by a mechanism independent of cAMP activation. However, measurement of stress-induced thermotolerance in two mutant strains (tpk1, tpk2, TPK3; tpk1, TPK2, tpk3) each deficient in two of the catalytic subunits of the cAMP-dependent protein kinase (cAPK), revealed that sublethal heat induces thermotolerance by a mechanism part-mediated by the catalytic subunits of cAPK. In contrast, 2iP and ethanol induced thermotolerance by a mechanism fully dependent on the catalytic subunits of cAPK for expression. Therefore, this implies there must be an alternative novel mechanism, other than cAMP, for activating cAPK during stress. Sublethal heating resulted in large increases in intracellular trehalose levels which correlated with the induction of thermotolerance. However, incubation in 2iP or ethanol had no significant effect. This suggests trehalose synthesis is either coincidental with heat stress or that different stress factors induce thermotolerance by alternative mechanisms. Incubation with protein synthesis inhibitors reduced the levels of trehalose synthesized during sublethal heating, suggesting that synthesis of trehalose-6-phosphate synthase during heat stress could be accounting for the increased trehalose levels.

Adaptation, Physiological↗
PubMed1991

Level and form of psychopathology and the structure of group therapy.

Drawing upon concepts derived from ego psychological and object relations psychoanalytic theories of individual development and from a depth group psychology, the present empirical study, a naturalistic field investigation, explored hypothesized relationships between aspects of patients' psychological boundaries and structural features of inpatient therapy groups. More specifically, patients were assessed in terms of their level (i.e., psychotic vs. borderline organization) and form (i.e., anaclitic vs. introjective) of psychopathology. Their perceptions of themselves and of their therapy groups were measured following participation in two kinds of small group treatment designed to differ in terms of degree of internal structuring. Findings, generally supporting the hypotheses, showed the anaclitic borderline patients, in particular, to be most sensitive to structural variations and most adversely affected by an impersonal and highly structured treatment climate. Theoretical and practical implications of these findings were discussed.

Adult↗
PubMed1991

Thermal inactivation of Listeria monocytogenes studied by differential scanning calorimetry.

The effect of NaCl on the thermal inactivation of Listeria monocytogenes has been investigated by conventional microbiological techniques and by using differential scanning calorimetry (DSC). Addition of 1.5 M-NaCl to cells grown at lower NaCl concentrations significantly increases the tolerance of cells to mild heat stress (56-62 degrees C). DSC thermograms show five main peaks which are shifted to higher temperatures in the presence of 1.5 M-NaCl. Measurement of loss of viability in the calorimeter gave good correlation between cell death and the first major thermogram peak at two NaCl concentrations. The time course of the loss of this first peak when cells were heated and held at 60 degrees C in the calorimeter matched the loss of viability, whereas the peak attributable to DNA showed little change during this process. The use of DSC to investigate the mechanisms involved in thermal inactivation is discussed.

Calorimetry, Differential Scanning↗
PubMed1991

Induction of increased thermotolerance in Saccharomyces cerevisiae may be triggered by a mechanism involving intracellular pH.

Incubation of Saccharomyces cerevisiae at sub-lethal temperatures results in an increase in thermotolerance. This process is dependent not only on the sub-lethal temperature but also on the duration of sub-lethal heating. This indicates that the mechanism inducing thermotolerance is a time/temperature dose response. Other factors that induce thermotolerance include exposure to ethanol, sorbic acid and low external pH values. These factors induce thermotolerance after incubation in the presence of protein synthesis inhibitors, and they are all known to affect the intracellular pH (pHi). The acquisition of increased thermotolerance is minimal with sub-lethal heating under neutral external pH conditions. However, when the external pH is reduced to 4.0 the level of induced thermotolerance increases to a maximum value. Using a specific ATPase inhibitor, diethylstilboestrol (DES), ATPase activity was shown to be essential for the cell to survive heat stress. In addition, measurement of acid efflux, or ATPase activity, revealed that proton pumping from the cell increased by approximately 50% at sublethal temperatures that induce thermotolerance. This work has clearly implicated pHi perturbation as the triggering mechanism conferring thermotolerance on S. cerevisiae.

Adaptation, Physiological↗
PubMed1991

Thermal inactivation of Listeria monocytogenes during a process simulating temperatures achieved during microwave heating.

Conventional heating was used to expose cells of Listeria monocytogenes, either in broth or in situ on chicken skin, to the mean times and temperatures that are achieved during a 28 min period of microwave cooking of a whole chicken. Heating L. monocytogenes by this method in culture broth resulted in a reduction in viable cell numbers by a factor of greater than 10(6) upon reaching 70 degrees C. Simulated microwave cooking of L. monocytogenes in situ, on chicken skin, resulted in more variability in the numbers of survivors. Heating for the full cook time of 28 min, however, resulted in a mean measured temperature of 85 degrees C and no surviving listerias were detected. This indicated a reduction in viable numbers of greater than 10(6). To reduce temperature variation, cells were heated on skin in a submerged system in which exposure to 70 degrees C for 2 min resulted in a reduction in viable cell numbers of all strains of listerias tested of between 10(6) and 10(8). These results show that when a temperature of 70 degrees C is reached and maintained for at least 2 min throughout a food there is a substantial reduction in the numbers of L. monocytogenes. The survival of this organism during microwave heating when temperatures of over 70 degrees C are reported is probably due to uneven heating by microwave ovens resulting in the presence of cold spots in the product. The heat resistance of L. monocytogenes is comparable with that of many other non-sporing mesophilic bacteria.

Animals↗
PubMed1990

The effect of pH, salt concentration and temperature on the survival and growth of Listeria monocytogenes.

Factorially designed experiments have been used to study the growth and survival of Listeria monocytogenes in different combinations of pH and salt concentrations at ambient and chill temperatures. Survival at low pH and high salt concentration was strongly temperature dependent. The minimum pH values that allowed survival after 4 weeks from an initial 10(4) cells were 4.66 at 30 degrees C, 4.36 at 10 degrees C and 4.19 at 5 degrees C. These limits were salt dependent, low (4-6%) salt concentrations improved and higher concentrations reduced survival at limiting pH values. The lowest pH that allowed a 100-fold increase in cell numbers within 60 d was 4.66 at 30 degrees C but this was increased to 4.83 at 10 degrees C. At 5 degrees C growth occurred at pH 7.0 but not at pH 5.13. Simple predictive models describing the effect of hydrogen-ion and salt concentration on the time for at least a 100-fold increase in numbers at 10 degrees C and 30 degrees C were constructed after analysis of the results for a least squares fit to a quadratic model. The interactions between salt and hydrogen-ion concentration on growth were found to be purely additive.

Colony Count, Microbial↗
PubMed1990

Balloon embolectomy catheter-induced arterial injury: a comparison of four catheters.

This study compared four brands of balloon embolectomy catheters with respect to their mechanical characteristics and the histologic responses they elicit. Seventy-two 4F Becton-Dickinson, Edwards, Electro-Catheter, and Shiley catheters were studied. In vitro studies of penetration forces demonstrated that the forces required for arterial puncture were greatest for Shiley (295 +/- 22 gm) and least for Edwards catheter tips (217 +/- 11 gm) (p less than 0.05). This indicates that the Shiley catheter is least likely to puncture vessels in patients. Studies of balloon eccentricity showed that none of the balloons distended with excessive eccentricity. Studies of balloon emptying time demonstrated that the silicon Becton-Dickinson balloon required more than two times as long (5.7 +/- 1.2 seconds) as all other balloons to empty. Balloon emptying time reflects the ability of the surgeon to rapidly adapt the balloon to changing vessel diameter in patients. Shear forces were studied in cylindrical segments of arteries in vitro. Initial shear forces were significantly different among all catheters, Becton-Dickinson greater than Edwards greater than Shiley greater than Electro-Catheter (p less than 0.05). In contrast, during catheter withdrawal dynamic shear forces were similar among the four brands of catheters. Balloon embolectomies were performed in vivo in the common carotid and common femoral arteries in 18 anesthetized dogs. Histologic examinations of the vessels exposed to 50, 100, and 200 gm shear forces showed that myointimal hyperplasia increased with rising shear forces for all catheters (p less than 0.05), but that there were no differences in the degree of myointimal hyperplasia elicited by the different brands of catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Early myointimal hyperplasia after balloon catheter embolectomy: effect of shear forces and multiple withdrawals.

Arterial stenosis occurring after balloon catheter embolectomy may be caused by myointimal hyperplasia (MIH). This study investigated the effects of shear force and repeated catheter withdrawals on the development of MIH after embolectomy. The procedures were performed in the common carotid and common femoral arteries of 18 anesthetized dogs. During catheter withdrawal, the balloons were filled gradually to produce shear forces rising smoothly from 50 to 200 gm. Four weeks after embolectomy, the vessels were perfusion-fixed in situ with 2% glutaraldehyde and were excised. The thickness and circumferential extent of MIH were measured in cross sections from segments of the vessels exposed to shear forces of 50, 100, and 200 gm. Sixty-nine of 72 arteries remained patent. Low shear force (50 gm) consistently elicited less MIH than did higher shear forces (p less than 0.05). At each level of shear force, repeated withdrawals resulted in greater circumferential extent of MIH than did single withdrawals (p less than 0.005). Although clinically it usually is necessary to perform multiple passes during balloon embolectomy, these data suggest that, in humans, attempts should be made to perform a minimal number of catheter withdrawals at low shear force to minimize the subsequent development of MIH.

Animals↗
PubMed1986

Synergistic effects of weak-acid preservatives and pH on the growth of Zygosaccharomyces bailii.

In completely randomised factorial experiments, individual and synergistic effects of pH, benzoic acid and sorbic acid on the growth rate of the yeast Zygosaccharomyces bailii were determined, and expressed in polynomial equations. Synergism between benzoic and sorbic acid was pH dependent. A distinct effect of the anionic form of benzoic acid on doubling time was demonstrated by experiments in which concentrations of benzoic acid and benzoate were varied. The resultant polynomial equation showed that both species act synergistically.

Benzoates↗
PubMed1985

Starting a level I fieldwork program.

In response to the occupational therapy students' need for meaningful early experiences in the clinical setting, an educational strategy was devised for marketing and implementing an occupational therapy clinical program for hospitalized psychiatric patients, which involves students in all aspects of its implementation. The pilot program was started at the Veterans Administration Medical Center in West Haven, CT, on a long-term psychiatric unit. This unit's previously limited occupational therapy services were expanded by the student program. The program has also extended into an acute psychiatric unit and a psychiatric day treatment program (which previously had not provided occupational therapy services). Sixteen to thirty Quinnipiac College junior occupational therapy students (per semester) were involved in assessment, treatment planning, program planning, administration, and documentation and evaluation under the close supervision of the occupational therapy educator. Students, patients, and administrators were surveyed, and the results were reported. For the first class of participants, the two significant learning outcomes were an improvement in attitude toward patients and an increased level of comfort in working with them.

Humans↗
PubMed1984

Alteration of cartilage matrix morphology with histological processing.

An interlacunar network in the extracellular matrix of femoral head articular cartilage of neonatal rats was seen by light microscopy to: (1) consist of elements, 0.5 micron thick, which occurred as individual elements, as bundles of elements, and as fused elements, (2) stain intensely with toluidine blue, methylene blue, and safranin O, and (3) connect chondrocytes by inserting on the chondrocyte capsules which were composed of morphologically and cytochemically similar material. By electron microscopy, the single elements were seen to be composed of thicker, denser staining areas of the honeycomb appearing matrix and the fused elements appeared as non-membrane bound channels containing granular material. Articular cartilage was processed using combinations of fixatives, dehydrating agents, and embedding media. Regardless of fixation, demineralization, or embedding, the network was not seen after dehydration of the cartilage with methanol, ethanol, acetone or tert-butanol but was seen after dehydration with aqueous solutions of glycol methacrylate, propylene oxide, 2-propanol or 2,2-dimethoxypropane. Network visualization following a variety of methods demonstrated that no single fixative, dehydrating agent, or embedding medium caused its formation. The presence of the network in different cartilage zones, its consistent morphology by light and electron microscopy, the uniformity of the elements in their connection with the chondrocytes, and presence in fresh-frozen sections suggest the network may be real, but rigorous evidence for its existence in vivo is still required. Since cartilage morphology was altered by histological methods, especially dehydration, common methods used in studying connective tissue matrix should be evaluated to determine their effect on matrix morphology.

Animals↗
PubMed1984

Methods and results of testing "low acid" glycol methacrylate (GMA) for light microscopic cytochemistry.

Four samples of "low acid" and one sample of "technical grade" glycol methacrylate from three commercial sources were compared for their suitability in light microscopic cytochemistry. The "technical grade" was found unacceptable, but the four "low acid" products were found to be essentially the same in terms of water and ethanol miscibility, pH, polymerization time, sectioning qualities, and lack of background staining with methylene blue.

Acrylates↗
PubMed1984

Disappearance of the cartilage interlacunar network during histological dehydration.

The interlacunar network connects adjacent chondrocytes in rapidly growing cartilage and with anionic dyes stains more intensely than the surrounding matrix. The network is seen in fresh-frozen sections and sections treated with a variety of fixatives, dehydration agents and embedding media. The network is not seen after using such common dehydrating fluids as ethanol and acetone. Polyanionic glycosaminoglycans (GAG) are abundant in the cartilage matrix and it has been suggested that the network is an artifact caused by a rearrangement of the matrix GAG during histological processing. Extraction of GAG from neonatal rat cartilage with guanidine hydrochloride removes stainable extracellular matrix but not the interlacunar network. However, after extraction of GAG and immersion of the cartilage in either 50% or 100% aqueous ethanol or acetone, the network was no longer visible. The network apparently is not an artifact formed by soluble matrix GAG, but a real structure which is extracted, collapsed or otherwise destroyed during dehydration in ethanol or acetone.

Animals↗
PubMed1984

Staining glycol methacrylate embedded cartilage with triethyl-carbocyanin DBTC ("ethyl-stains all") with special reference to the interlacunar network.

The dye, triethyl-carbocyanin DBTC, was tested for differential staining of cartilage structures. Femoral head articular cartilage from neonatal rats was processed for histology to demonstrate the interlacunar network. Sections of glycol methacrylate (GMA) embedded cartilage were stained at pH 2.8, 5.4, 6.1 and 8.0 to determine the optimal staining conditions. Only at pH 6.1 were all cartilage structures stained and the best contrast achieved. Streptomyces hyaluronidase, chondroitinase ABC, pepsin, trypsin, and pronase digestions were carried out prior to staining at pH 6.1 to evaluate the selectivity of the stain. Undigested chondrocyte nuclear chromatin stained dark purple; staining intensity was reduced slightly by pepsin or trypsin digestion. Undigested chondrocyte cytoplasm stained light blue but stained purple after hyaluronidase digestion. Undigested extracellular matrix stained light violet; staining was almost entirely eliminated by chondroitinase ABC digestion, was unaffected by hyaluronidase, and was either unaffected or increased after proteinase digestion. Staining of a narrow zone of matrix adjacent to the network was prevented by proteinase digestion while the network element appeared as a thin dark line. The network appears to be a trilaminar structure; a core element of hyaluronic acid and protein surrounded by a protein sheath. Triethyl-carbocyanin DBTC staining of cartilage offers slightly more selectivity and contrast than methylene blue, toluidine blue or safranin O. At pH 6.1, DNA, perhaps RNA, and hyaluronic acid stained deep purple; chondroitin sulfate, light violet; protein (collagen), stained very light violet if at all.

Animals↗
PubMed1983

Morphological evidence of the shedding of chondrocytes from the articular surface in neonatal rats: relationship to the interlacunar network.

The superficial zone of the femoral head articular cartilage of 5- to 15-day old rats was examined by light and electron microscopy for evidence of shedding into the joint space. Chondrocytes deepest in the superficial zone were round, surrounded by a capsule, and connected to adjacent chondrocytes by the interlacunar network, whereas cells in the middle of the zone appeared similar but with less cytoplasm. At the circular surface, chondrocytes were small, with pyknotic nuclei and poorly defined organelles. These cells occasionally protruded from the articular surface but maintained at least partial connection with the network and their capsule. Depressions in the articular surface were lined with material similar to that of the network and were the only locations found where the network did not terminate at a cell surface. This static evidence suggested at least two hypotheses: 1) Degenerating chondrocytes moved up through the superficial zone to the articular surface and were shed into the joint space. This movement may be facilitated by the network as part of neonatal cartilage development. 2) During joint formation, the surface of the articular cartilage was eroded down to the chondrocytes, which were exposed to the joint fluid, causing cell degeneration, death, and shedding. Evidence of cell shedding was rarely seen after 2 weeks of age. Likewise, the interlacunar network disappeared from the superficial zone during this period. A physiological as well as structural relationship may exist between the chondrocytes and interlacunar network.

Animals↗
PubMed1982

Glycol methacrylate embedding of bone and cartilage for light microscopic staining.

A method is described for embedding bone and cartilage in glycol methacrylate (GMA) for light microscopy. Dehydration-infiltration of the hard tissue is with aqueous GMA solutions minimizing solvent and dehydration artefact, and polymerization is by UV light in the cold to minimize thermal damage. Over fifty stains, enzyme localizations and related histochemical methods for 0.5-3.0 micrometer thick sections of GMA embedded tissue are listed. The increased resolution plus the localization of cellular and extracellular chemical moieties is now easier and more accurate providing an improved method for the study of the musculo-skeletal system by light microscopy histochemistry.

Animals↗
PubMed1982

Morphology of the interlacunar network in four sites of hyaline cartilage of neonatal, juvenile, and adult rats.

The honeycomb matrix and interlacunar network are described and compared in femoral head articular cartilage, proximal femoral physis, xiphoid, and tracheal cartilages from neonatal, juvenile, and adult rats. The honeycomb matrix is morphologically constant in all four sites of all age groups. The network is plentiful in cartilage of neonatal rats, reduced in juveniles, and rare in adults. In a given cartilage site, the network has a constant pattern and concentration gradient among rats of the same age. It is hypothesized that the network functions only during rapid cartilage growth and is not related to weight-bearing. The network is composed of element sheets averaging 0.5 micrometer in thickness, which connect adjacent chondrocytes. Ultrastructurally, the network is observed as the thickened, dense areas of the honeycomb matrix and as nonmembrane-bound channels of granular material. The network and chondrocyte capsules are morphologically and cytochemically similar.

Aging↗