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Y Cruz

Publications and source records attributed to Y Cruz.

11 recordsLinked to original sources
PubMed2005

Histopathological and behavioral characterization of a novel cervical spinal cord displacement contusion injury in the rat.

Cervical contusive trauma accounts for the majority, of human spinal cord injury (SCI), yet experimental use of cervical contusion injury models has been limited. Considering that (1) the different ways of injuring the spinal cord (compression, contusion, and transection) induce very different processes of tissue damage and (2) the architecture of the spinal cord is not uniform, it is important to use a model that is more clinically applicable to human SCI. Therefore, in the current study we have developed a rat model of contusive, cervical SCI using the Electromagnetic Spinal Cord Injury Device (ESCID) developed at Ohio State University (OSU) to induce injury by spinal cord displacement. We used the device to perform mild, moderate and severe injuries (0.80, 0.95, and 1.1 mm displacements, respectively) with a single, brief displacement of <20 msec upon the exposed dorsal surface of the C5 cervical spinal cord of female (180-200 g) Fischer rats. Characterization of the model involved the analysis of the temporal histopathological progression of the injury over 9 weeks using histochemical stains to analyze white and gray mater integrity and immunohistochemistry to examine cellular changes and physiological responses within the injured spinal cord. Accompanying the histological analysis was a comprehensive determination of the behavioral functionality of the animals using a battery of motor tests. Characterization of this novel model is presented to enable and encourage its future use in the design and experimental testing of therapeutic strategies that may be used for human SCI.

Animals↗
PubMed2001

Purification and conformational properties of a human interferon alpha2b produced in Escherichia coli.

Recombinant human interferon alpha2b was expressed intracellularly in Escherichia coli as insoluble aggregates using a new expression vector, and was purified to homogeneity using essentially two-step chromatographic procedures, i.e. immobilized metal-ion-affinity chromatography and reversed-phase HPLC. The established purification process is highly reproducible and leads to a total recovery of approx. 12% with a specific biological activity of higher than 1x10(8) i.u./mg of protein, which is comparable with the international requirement for interferon alpha2b. For purified protein we report conformational stability as a function of pH and temperature using differential scanning calorimetry and CD. Thermal unfolding as a function of pH showed only one endotherm at a temperature higher than 45 degrees C, and was reversible at pH 2-3.75 and irreversible at pH 4-10. At pH 7.0, the most stable condition, the conformational stability depends on protein concentration and ionic strength. The highly helical secondary structure is very conserved over the whole pH range studied, including at high temperatures.

Calorimetry, Differential Scanning↗
PubMed1999

Temporal and behavioral patterning of parturition in rabbits and rats.

Although the rabbit (Oryctolagus cuniculus) continues to play an important role in the study of parturitional processes, a detailed behavioral description of birth in this species, necessary for accurately assessing the effects of experimental manipulation, is lacking. It is the aim of this report to provide such a description and to compare it with corresponding behavior in the better-studied rat. Ten pregnant chinchilla-breed rabbits and 10 pregnant Wistar rats were placed in glass-bottomed observation cages 2 days before term, and their behavior recorded on closed-circuit video, viewing the animals from below. All aspects of parturition were accomplished much faster in rabbits than rats; latency to birth of first pup, rate of delivery, duration of vaginal retention, time spent by mothers eating placentas, and in licking and nursing pups. In contrast to rat pups, rabbits were usually born separated from the placenta and already free from membranes. They were much more active, and well able to cast off any remaining membranes, suckle, and survive, whether directly attended to by the mother or not. We conclude that the tight temporal organization of events in the rabbit provides an unusually sensitive assay for investigating mechanisms underlying mammalian parturition.

Animals↗
PubMed1998

The sensory but not muscular pelvic nerve branch is necessary for parturition in the rat.

In the rat the pelvic nerve consists of a viscerocutaneous (sensory) branch which receives information from pelvic viscera and the midline perineal region, and a somatomotor (muscular) branch which innervates the ilio- and pubococcygeous muscles. To investigate the contribution of these branches to the parturition process, the length of gestation and course of delivery were closely monitored in 43 pregnant, Wistar-strain rats randomly assigned to five groups: untreated control animals, animals in which the somatomotor branch of the pelvic nerve was bilaterally sectioned on Day 14 of gestation, animals in which the viscerocutaneous branch of the pelvic nerve was bilaterally sectioned on Day 14 of gestation, animals treated similarly to the previous group but with young delivered by C-section at term, and sham-operated controls. Sectioning the viscerocutaneous branch seriously disrupted parturition and resulted in major dystocia and a high percentage of stillbirths in all females. In contrast, sectioning the somatomotor branch had no apparent effect on parturition and no significant differences were found between females of this group and sham or control dams on any of the measures recorded. It is concluded that the viscerocutaneous branch of the pelvic nerve is vital for the normal course of parturition in the rat but that the somatomotor branch plays little role, if any.

Abdominal Muscles↗
PubMed1997

PCR detection of human papillomavirus: comparison between MY09/MY11 and GP5+/GP6+ primer systems.

Human papillomavirus (HPV) is an etiologic agent of cervical cancer and is the most common sexually transmitted disease in women. PCR amplification of HPV genomes is the most sensitive method for the detection of cervicovaginal HPV. We have compared the two most commonly used PCR primer sets, MY09/MY11 (MY-PCR) and GP5+/GP6+ (GP+-PCR), for the detection of HPV DNA in cervicovaginal lavage samples from 208 women. Oligonucleotide probes for 39 different HPV types were used. Both primer sets amplified a wide spectrum of HPV genotypes and detected similar overall prevalences of 45% (94 of 208) and 43% (89 of 208), respectively. The MY-PCR system detected 27 of 30 (90%) samples with multiple HPV types, whereas the GP+-PCR system detected 14 of 30 (47%) samples with multiple HPV types. Differences in the detection of HPV types 35, 53, and 61 were noted between the two primer systems. Serial dilution of plasmid templates indicated a 3-log decrease in the amplification of HPV type 35 by MY-PCR and HPV types 53 and 61 by GP+-PCR. These results indicate that although the MY-PCR and GP+-PCR identified nearly equivalent prevalences of HPV in a set of clinical samples, differences in the detection of specific types and infections with multiple types were found. Differences in the sensitivities and characteristics of the PCR systems for the detection of HPV within clinical samples should be considered when comparing data between studies and/or in designing new studies or clinical trials.

DNA Primers↗
PubMed1996

Changes in pain threshold during the reproductive cycle of the female rat.

Responsiveness to pain was determined in female rats across the whole reproductive cycle using the tail-flick test. When tested immediately after mating, pain thresholds were unaltered, whereas 10 min later animals typically demonstrated hyperalgesia (Experiment 1). They also demonstrated hyperalgesia during most of pregnancy, and had significantly lower pain thresholds than the unmated controls except for the 24 h before parturition, when a sudden increase in tail-flick latencies was recorded (Experiment 2). Pain thresholds were also significantly lower throughout the nursing period but increased significantly when dams were separated from their litters for 6 h, and returned to premating baseline values within 24 h of weaning (Experiment 3). These findings confirm and extend earlier reports that female reproductive state may significantly modify responsiveness to noxious stimuli, and it is suggested that differences between the results of this and previous studies may be at least partly explained by the relatively stress-free test procedure adopted here.

Animals↗
PubMed1994

Analysis of short novel human papillomavirus sequences.

Consensus primer mediated PCR protocols have the potential to amplify previously uncharacterized human papillomavirus (HPV) genotypes. In a study on 500 cervicovaginal samples, we amplified four sequences (L1AE 1 to L1AE 4) that failed to hybridize to any of the available HPV type-specific oligonucleotide probes. Nucleotide sequencing revealed that the sequences were derived from the L1 region of hitherto unsequenced genotypes. Comparison of phylogenetic trees based on the amplified L1 sequences with E6-derived phylogenetic trees resulted in the identification of L1AE 1 and L1AE 2 as putative novel HPV PCR genotypes. L1AE 1 was related to HPV 39, whereas L1AE 2 was related to HPV 51. The L1AE 3 and L1AE 4 sequences occupied L1-phylogenetic branches equivalent to the positions of HPV 66 and HPV 61, respectively, in an E6-phylogenetic tree.

Amino Acid Sequence↗
PubMed1994

Assessing pain threshold in the rat: changes with estrus and time of day.

Pain threshold was determined in female rats using the tail flick test. Latency to respond depended on the locus of the tail heated, with the most distal sites resulting in the shortest response times (Experiment 1). Tail flick latency also varied according to the time of day, with shorter response times recorded around the middle of the dark phase than near its beginning or after its end. This was the case for intact, for ovariectomized, and for ovariectomized, estradiol-treated rats (Experiment 2). However, response times also varied across the estrous cycle, with significantly shorter latencies recorded during estrus and metestrus. Ovariectomy abolished these fluctuations, and whereas administration of estradiol increased response times, progesterone had little effect (Experiment 3). These results suggest that site of tail heating, time of day, and presence of ovarian hormones can influence tail flick latency independently, thus demonstrating the complexity of the mechanisms that may contribute to pain threshold even within the same paradigm.

Animals↗