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Biomedical subjects

K A Allen

Publications and source records attributed to K A Allen.

At least 19 recordsLinked to original sources
PubMed2001

A new era for the Pap test.

Utilization of liquid-based Pap testing is a significant improvement in women's health care. Increased diagnostic sensitivity and improvement of specimen adequacy are seen with its use. When combined with HPV testing, the uncertainty associated with waiting for additional testing is eliminated and additional unnecessary procedures, such as colposcopy, can be reduced. This relatively simple collection system will allow significant advances in molecular epidemiology and, in the future, development of a molecular Pap test.

Adult↗
PubMed2000

Evaluation methods for assessing cytotechnology students' screening skills.

The development of slide screening skills to achieve diagnostic accuracy is the goal of cytotechnology education. There is limited time in the typical cytotechnology training program in which to acquire the didactic knowledge as well as screening experience. It is easier to teach the morphologic criteria necessary to refine diagnostic skills, but more difficult to teach and acquire locator skills. A survey was conducted to document and assess methods of evaluating screening skills utilized by U.S. cytotechnology educational programs. Graduation requirements and grading methods related to slide screening volume and accuracy were provided by survey participants. Current methods are varied, but appear to be effective in assessing diagnostic accuracy and graduate competence. A considerable period of time is required for students to gain enough screening experience to perform at required levels of volume and accuracy.

Cell Biology↗
PubMed1999

A radical demise. Toxins and trauma share common pathways in hair cell death.

The pathologic similarities noted after ototoxic and/or traumatic injury to the cochlea as well as the key features of the cochlea that make it susceptible to reactive oxygen species (ROS) damage are reviewed. Recent evidence linking ROS to cochlear damage associated with both ototoxins and/or trauma are presented. Mechanisms of generation of ROS in the cochlea and how these metabolites damage the cochlea and impair function are also reviewed. Finally, examples of novel therapeutic strategies to prevent and reverse hearing loss due to noise and/or ototoxins are presented to illustrate the clinical relevance of these new findings.

Aminoglycosides↗
PubMed1998

Lower extremity preference during gross and fine motor skills performed in sitting and standing postures.

The evaluation of lower limb preference in physical therapy practice is critical in order for the clinician to assist patients with functional retraining tasks. No studies in the physical therapy literature present a systematic approach to determine the criteria needed to identify the preferred limb. This research was designed to present a series of tests for effectiveness in determining limb preference. The purpose of this study was to determine whether lower limb preference existed in a group of recreationally athletic women when performing either stability or dynamic skills with the lower extremities while sitting or standing. The relationship of such a preference to handedness was also determined. Forty female recreational athletes, 20 right-handed subjects and 20 left-handed subjects, who ranged in age from 21 to 35 years, participated in this study. Subjects performed three repetitions of the following tests in both sitting and standing: kick a ball, swing a leg over a box, pick up a marble with the toes, and trace a triangle with the toes. The subjects were also asked to stand on one leg. The order of performing the tests was randomized. The results indicated that right-handed subjects performed activities more consistently with one lower extremity when compared with left-handed subjects, regardless of posture (sitting or standing). The difference in limb choice between right- and left-handed subjects was significant for all activities (p < .05). The considerable sensitivity of foot and leg performance following neurological insult renders the assessment of foot and leg preference very important for purposes of clinical rehabilitation.

Adult↗
PubMed1995

Ocular surface flora in drowning victims.

Contaminated allograft donor tissue represents a potential source of infection unique to keratoplasty. We prospectively studied perilimbal cultures of drowning victims over 30 months to determine if the ocular surface flora of drowning victims was unique. Twenty-eight donor eyes were cultured from 14 drowning victims. Ninety-three percent of limbal cultures were positive for one or more organisms, compared to results of a previous study of surface contamination of donor globes in which 65% were found to be culture positive. Fifty-seven percent (16 of 28) of donor eyes grew at least one streptococcal species, while 46% (13 of 28) grew two or more streptococcal species. A previous study identified streptococcal species in 7.9% of perilimbal cultures from nondrowning donor eyes, which demonstrates the unique effect of drowning on the ocular flora. The incidence of gram-negative isolates was also markedly higher in drowning victims, compared to previous studies of donor globes. This prospective study has shown that the ocular surface flora of drowning victims harbors markedly increased numbers of streptococcal species as well as gram-negative organisms. These findings demand careful globe decontamination, and emphasize the need for appropriate antibiotic coverage in corneal storage media.

Adolescent↗
PubMed1995

Laboratory use of the diagnosis "reactive/reparative" in gynecologic smears: impact of CLIA '88.

The Clinical Laboratory Improvement Amendments of 1988 (CLIA '88) contain regulation 493.1257(c)(1), which states: "[A]ll gynecologic smears interpreted to be showing reactive or reparative changes are confirmed by a technical supervisor in cytology." We surveyed 500 cytology laboratories to assess the utilization of the diagnosis "reactive/reparative" (R/R) for gynecologic cytology examinations. One hundred and seventy participants (34%) returned an acceptable questionnaire that described their use of this terminology, the technical supervisor's (pathologist's) role in the evaluation of these cases, and the volume of cases with this diagnosis. Prior to CLIA '88, 86 (51%) laboratories did not forward to a pathologist gynecologic smears reported as showing R/R changes, and this decreased to 20 (12%) after implementation of CLIA '88. Thirty-six (21%) laboratories changed their criteria for reporting R/R changes after CLIA '88. No correlation was noted between the demographics of the laboratory (e.g., size, type of practice affiliation, accreditation) and familiarity with this regulation. Based on the case volumes provided in the survey results, the estimated cost to the nation of complying with this single regulation is between $4.5 million and $40 million. The interpretation of and financial impact of compliance with this one selected regulation of CLIA '88 is reported.

Cytological Techniques↗
PubMed1995

Bronchoalveolar lavage in the diagnosis of low-grade, MALT type, B-cell lymphoma in the lung.

Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type represents one of the most frequent primary lymphomas in the lung. This study demonstrates the value of bronchoalveolar lavage (BAL) in the diagnosis of this entity. Three patients with biopsy proven MALT lymphoma in the lung were submitted to bronchoscopy. BAL fluid analysis showed an increased cellularity and a striking lymphocytosis. Cytological features consistent with a low-grade malignant lymphoma were present in two cases (medium sized lymphoid cells with an evident lymphoplasmocytoid differentiation, and irregular nuclear borders). In all cases, flow cytometry analysis showed a high percentage of cells expressing a B phenotype (52, 40 and 28%, respectively). In two cases, there was a striking monotypic expression of surface light-chain immunoglobulin (Kappa/Lambda ratio = 38 and 0.04, respectively). Bronchoalveolar lavage appears to be a valuable procedure in the diagnosis of low-grade B-cell lymphoma of MALT type in the lung.

B-Lymphocytes↗
PubMed1994

Review of negative Papanicolaou tests. Is the retrospective 5-year review necessary?

New federal regulations require review of all available negative gynecologic smears within the previous 5 years for each patient with a current high grade squamous intraepithelial lesion (HGSIL) or above. Two university hospitals retrospectively reviewed all patients who had HGSIL or above and who had prior negative smears. During 18 months, 35,807 Papanicolaou tests were reported, from which we identified 44 patients with 80 negative smears before presenting with HGSIL or above. These 80 negative smears were rescreened and, on review, there was agreement with the original diagnosis in 66 cases (82.5%). Fourteen (17.5%) smears were reclassified: 2 unsatisfactory, 6 atypical squamous/glandular cells of undetermined significance, 3 low grade SIL, and 3 HGSIL or above. Of the 12 cases satisfactory for reclassification, 9 (75%) occurred within 2 years before the HGSIL or above. Two cases of atypical squamous/glandular cells occurred within 4 years. One case of HGSIL occurred more than 4 years before, but a negative Pap smear had been reclassified within the year before the diagnosis of HGSIL. The authors conclude that a 2-year retrospective review, which identified 75% of our false-negative cases, is an effective and efficient quality control and assurance practice.

False Negative Reactions↗
PubMed1994

The role of sex and genotype on antiorthostatic suspension effects on the mouse peripheral skeleton.

Previous antiorthostatic suspension studies have used a single sex and strain of rat or mouse. Nonetheless, broadly similar effects of suspension on the two species indicates a generalized effect of suspension not attributed to specific genetic, behavioral, or sex-linked etiology. In order to directly test genetic and sex-linked factors, the effects of suspension on the appendicular bone of male and female BALB-CJ, C57BL-6J, and DBA-2J mice were compared. These genotypes were selected based on their widely different developmental and behavioral characteristics as well as on past research involving a heterogeneous strain derived from these strains. The effects of suspension on the geometric, mechanical, and material properties of the femora, humeri, and tibiae were determined. Among the bone types, the femora were most significantly affected by suspension. The effects of suspension were similar in nature in male and female mice aged 1.7 months. Strain-dependent suspension effects may be indicative of bone developmental differences in the strains at the age chosen.

Animals↗
PubMed1993

Calcium dependence of differentiation of GABA immunoreactivity in spinal neurons.

The developmental regulation of neurotransmitter synthesis has been extensively studied and appears in many cases to depend on electrical activity. The central nervous system of the Xenopus embryo and young larva is an attractive subject for such studies, since action potentials first elicited from Xenopus spinal neurons at the time of closure of the neural tube are long in duration and calcium-dependent. Moreover, cells exhibit spontaneous elevations of intracellular calcium during this early period as a consequence of calcium influx through voltage-dependent channels, which induces calcium release from intracellular stores. Since the early differentiation of Xenopus spinal neurons in dissociated cell culture parallels development in vivo, we have examined the maturation of gamma-aminobutyric acid (GABA) immunoreactivity in cultured neurons and explored its dependence on spontaneous calcium influx at early stages of development. We find that specific GABA immunoreactivity develops in spinal neurons in dissociated cell culture with the same time course previously defined in vivo. Additionally, this process requires calcium influx that occurs spontaneously through voltage-dependent channels. The appearance of GABA immunoreactivity is blocked by transcriptional inhibitors. The early appearance of GABA raises the possibility that it may play additional roles at early stages of development.

Animals↗
PubMed1993

Aging of the human photoreceptor mosaic: evidence for selective vulnerability of rods in central retina.

PURPOSE: Because previous studies suggested degeneration and loss of photoreceptors in aged human retina, the spatial density of cones and rods subserving the central 43 degrees of vision as a function of age was determined. METHODS: Cones and rods were counted in 27 whole mounted retinas from donors aged 27 to 90 years with macroscopically normal fundi. Photoreceptor topography was analyzed with new graphic and statistical techniques. RESULTS: Changes in cone density throughout this age span showed no consistent relationship to age or retinal location, and the total number of foveal cones was remarkably stable. In contrast, rod density decreased by 30%, beginning inferior to the fovea in midlife and culminating in an annulus of deepest loss at 0.5 to 3 mm eccentricity by the ninth decade. Space vacated by dying rods was filled in by larger rod inner segments, resulting in a similar rod coverage at all ages. At the temporal equator, cone density declined by 23%, but rods were stable throughout adulthood. CONCLUSIONS: The stability of both rod coverage and rhodopsin content despite decreasing cell number suggests plasticity of the adult rod system and that age-related declines in scotopic sensitivity may be due to postreceptoral factors. There is no evidence for the massive loss of foveal cones required to explain even modest decrements in acuity, consistent with evidence that visual deficits at high photopic levels may be largely due to optical factors. Why the rods of central retina, which share a common support system and light exposure with the neighboring cones, are preferentially vulnerable to aging remains to be determined.

Adolescent↗
PubMed1992

Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension.

The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

Animals↗
PubMed1992

New testing approaches in transfusion medicine.

A revolution has occurred in the availability of molecular diagnostic technology in the last decade. We are just now beginning to bridge the gap between research and the availability of rapidly licensed clinical assays. Many of these new technologies will be useful in the general practice of transfusion medicine. Some of these techniques may be discarded as impractical. However, many of these methods should prove to be useful in clinical transfusion research and diagnosis.

Blood Transfusion↗
PubMed1991

Distribution and morphology of human cone photoreceptors stained with anti-blue opsin.

Primate cones maximally sensitive to short wavelength light (blue cones) have been previously identified by using indirect methods. We stained 7 wholemounted human retinas obtained from 6 female donors, using an affinity purified antibody to a 19 amino acid peptide sequence at the N-terminus of blue opsin (Lerea et al., '89: Neuron 3:367-376), standard PAP immunocytochemistry, and controls. Cones were counted where all outer segments could be traced to inner segments and were measured where cells were well aligned vertically. We find that: (1) 7% of cones within 4 mm of the foveal center are labeled by antiblue opsin; (2) compared to neighboring red/green cones, blue cone inner segments are 10% taller, have a larger cross-sectional diameter near the junction with the outer segment, and a smaller diameter near the external limiting membrane, resulting in a more cylindrical shape, (3) foveal blue cones are sparse, irregularly spaced, and missing in a zone about 100 microns (0.35 degrees) in diameter near the site of peak cone density, (4) the highest densities of blue cones (greater than 2,000 cells/mm2) are found in a ring at 0.1-0.3 mm eccentricity, and (5) the shortest distances between neighboring cones are between blue and red/green cones, and the blue and red/green mosaics are statistically independent. These findings are consistent with psychophysical reports of foveal tritanopia and maximum sensitivity to blue light at 1 degree eccentricity. Blue cone spacing may limit resolution of the blue channel out to 20-30 degrees eccentricity. The blue and red/green mosaics appear to be formed by separate processes.

Adolescent↗