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Biomedical subjects

D A Major

Publications and source records attributed to D A Major.

14 recordsLinked to original sources
PubMed2003

Modification of standard freezing media to limit capacitation and maximise motility of frozen-thawed equine spermatozoa.

OBJECTIVE: To investigate cryopreservation-induced capacitation-like changes in equine spermatozoa frozen in three different media using chlortetracycline (CTC) fluorescence staining analysis. PROCEDURE: Semen collected from three stallions was diluted in one of three centrifugation media and, after centrifugation and removal of supernatant, extended in corresponding freezing media containing additional egg yolk, glycerol, lactose and Equex paste. The semen was frozen in 5 mL straws and the spermatozoa assessed for motility and membrane quality after thawing. RESULTS: Following centrifugation, spermatozoa diluted with modified Kenney's Centrifugation Medium (MKCM) displayed a higher percentage of (normal) F pattern (94.3%) compared with spermatozoa in Kenney's Centrifugation Medium (KCM) (84.9%) and Glucose-EDTA Centrifugation Medium (GECM) (85.2%). Conversely, the percentage of spermatozoa displaying the (capacitated) B pattern was higher in the KCM (14.1%) and GECM (13.8%) than in the MKCM (5.0%). Following freezing-thawing, there were lower percentages of spermatozoa displaying the AR (acrosome reacted) pattern in modified Kenney's Freezing Medium (MKFM) (45.6%) compared with Kenney's Freezing Medium (KFM) (61.4%) and lactose-EDTA Freezing Medium (LEFM) (61.1%). There was a correspondingly higher percentage of spermatozoa displaying the B pattern in MKFM (52.3%) compared with KFM (37.9%) and LEFM (38.6%). There was no significant difference between the freezing media in the percentage of spermatozoa displaying the F pattern. The percentage of progressively motile spermatozoa was also influenced by the type of freezing medium (P < 0.001). Post-thaw percentages of progressively motile spermatozoa, frozen in MKFM, KFM, and LEFM, were 31.4, 25.8 and 23.3%, respectively. CONCLUSION: MKFM was the preferred medium for cryopreservation of equine spermatozoa due to its superior protection against changes in motility and membrane quality compared with the other freezing media studied.

Animals↗
PubMed2002

Capacitation-like changes in equine spermatozoa throughout the cryopreservation process.

Chlortetracycline (CTC) fluorescence staining analysis was used to investigate cryopreservation-induced capacitation-like changes in equine spermatozoa. Freshly ejaculated spermatozoa were found to display a high proportion of F pattern cells (uncapacitated; 93.6%) and a lower proportion of B pattern (capacitated; 5.4%) and AR pattern (acrosome-reacted; 1%) cells. Following cryopreservation in modified Kenney's medium, capacitation-like changes were observed. There was a significant increase in the proportion of spermatozoa displaying the B pattern (64.8%; P<0.001) and AR pattern (32.8%; P<0.001), with a corresponding decrease in the proportion of spermatozoa displaying the F staining pattern (2.5%; P<0.001). Further analysis of CTC fluorescence staining patterns showed that there was a major decrease in the proportion of F pattern spermatozoa corresponding to an increase in B pattern spermatozoa following removal of seminal plasma after centrifugation and resuspension in freezing medium. There was a further decline in the proportion of F pattern spermatozoa, corresponding to increases in B and AR pattern spermatozoa, after the freezing and thawing steps. Resuspension of centrifuged spermatozoa in homologous seminal plasma did not induce capacitation-like changes. These data indicate that the process of freezing and thawing stallion semen induces capacitation-like changes in spermatozoa and that most of the change is brought about by removal of seminal plasma, with further changes induced by the actual freezing and thawing step.

Acrosome Reaction↗
PubMed2001

Alcohol use and workplace aggression: an examination of perpetration and victimization.

PURPOSE: The purpose of the present investigation was to examine the relationship between victimization from and perpetration of workplace aggression between coworkers and frequency of alcohol use during the last year. METHODS: Civilian employees (N = 300) selected from the US population were interviewed over the telephone with psychometrically sound measures of workplace aggression and alcohol use frequency during the last year. Hierarchical regression analyses were used to examine the relationship between alcohol use and workplace aggression, after controlling for sociodemographic variables. RESULTS: Both percentage of days of any drinking and percentage of days of heavy drinking during the last year were positively related to (a) victimization from verbal and physical aggression at work and (b) perpetration of verbal and physical aggression at work. IMPLICATIONS: Consistent with research studies spanning the sociobehavioral literature, the present investigation found alcohol use was associated with perpetration of and victimization from verbal and physical workplace aggression. Although the study established an association exists between alcohol use and workplace aggression, future investigations should attempt to understand employee alcohol use in the context of a multifaceted model that includes other likely factors that contribute to the incidence of aggressive behavior on the job.

Adolescent↗
PubMed1999

Odorants presented to the rat nasal cavity increase cortical blood flow.

Complaints about unpleasant environmental odorants, both outdoor and indoor, are increasingly being reported. The main complaints of health symptoms from environmental odorants are eye, nose and throat irritation, headache and drowsiness. Complaints may arise from the stimulation of olfactory receptors or trigeminal chemoreceptors. Stimulation of cerebrovascular nociceptors originating from a branch of the trigeminal nerve may be associated with an increase in cortical blood flow which is thought to be related to headache. Since odorants are reported to elicit headaches, the possibility that odorants may increase cortical blood flow was examined. Cortical blood flow was monitored in rats using a laser-Doppler flowmeter. The flowmeter probe was placed over the left frontal cortex while propionic acid, cyclohexanone, amyl acetate or butanol was delivered to the nasal cavity via an olfactometer. Cortical blood flow increased as the concentration increased for three of the odorants tested. The greatest increase in blood flow occurred to the presentation of propionic acid, followed by cyclohexanone and amyl acetate. There was no response to butanol. These data demonstrate that odorants can alter cerebrovascular blood flow, which may account, in part, for one of the health symptoms reported for odorants.

Animals↗
PubMed1997

A new stable pluronic F68 gel carrier for antibiotics in contaminated wound treatment.

Pluronic F68 was selected as the gel carrier for antimicrobial agents because of its extensive use as a wound cleanser in humans without discernable side effects. When the concentration of this surfactant is increased to 46%, it forms a water soluble gel that can serve as a carrier for antimicrobial agents. The stability of this gel can be enhanced by immediately cooling (-15 degrees C) the gel for 24 hours before storage and subsequent application. Immediate cooling of the gel causes hydration of the surfactant that is associated with gel strengthening and prolonged shelf life stability. In experimental animals, this stable gel carrier containing 0.2% nitrofurazone significantly reduces the bacterial concentration of Staphylococcus aureus in wounds to a greater degree than silver sulfadiazine. This antimicrobial gel has the same antimicrobial activity as polyethylene glycol carriers containing 0.2% nitrofurazone, but does not carry the potential risk of polyethylene glycol intoxication.

Animals↗
PubMed1976

Brunner's gland adenomas associated with high-output congestive heart failure.

Brunner's gland adenoma in the third portion of the duodenum is rare and only two such cases have been reported previously. A 35-year old man presented with high-output congestive heart failure. Profound iron deficiency anemia was corrected by transfusion, allowing detection of a duodenal tumor, which proved pathologically to be a Brunner's gland adenoma.

Adult↗
PubMedDate not supplied

Influence of Biobrane construction on adherence.

Biobrane (standard adherence) and Biobrane L (light adherence) were compared for their degree of adherence to donor site wounds on rabbits at 1, 4, 7, and 9 days. Biobrane, which has more nylon fabric exposed to the wound surface, had significantly greater adherence levels to the wound at all time periods when compared with Biobrane L, which has less nylon fabric exposed to the wound.

Animals↗