Biomedical subjects

A Rademaker

Publications and source records attributed to A Rademaker.

64 records · Page 4Linked to original sources

PubMed1989

Electron microscopic quantification of collagen fibril diameters in the rabbit medial collateral ligament: a baseline for comparison.

To establish a normal baseline for comparison, thirty-one thousand collagen fibril diameters were measured in calibrated transmission electron (TEM) photomicrographs of normal rabbit medial collateral ligaments (MCL's). A new automated method of quantitation was used to compare statistically fibril minimum diameter distributions in one midsubstance location in both MCL's from six animals at 3 months of age (immature) and three animals at 10 months of age (mature). Pooled results demonstrate that rabbit MCL's have statistically different (p less than 0.001) mean minimum diameters at these two ages. Interanimal differences in mean fibril minimum diameters were also significant (p less than 0.001) and varied by 20% to 25% in both mature and immature animals. Finally, there were significant differences (p less than 0.001) in mean diameters and distributions from side-to-side in all animals. These mean left-to-right differences were less than 10% in all mature animals but as much as 62% in some immature animals. Statistical analysis of these data demonstrate that animal-to-animal comparisons using these protocols require a large number of animals with appropriate numbers of fibrils being measured to detect small intergroup differences. With experiments which compare left to right ligaments, far fewer animals are required to detect similarly small differences. These results demonstrate the necessity for rigorous control of sampling, an extensive normal baseline and statistically confirmed experimental designs in any TEM comparisons of collagen fibril diameters.

Animals↗

PubMed1988

Human sperm chromosome complements after microinjection of hamster eggs.

A technique was developed for microinjection of human spermatozoa into golden hamster (Mesocricetus auratus) eggs to obtain human pronuclear chromosome complements. Before microinjection the spermatozoa were treated by brief sonication or incubation in TEST-yolk buffer to reduce motility. Very few sperm chromosome complements developed after sperm treatment with sonication and the frequency of spermatozoa with structural chromosomal abnormalities was exceedingly high (91%). The majority of sperm chromosome complements analysed had multiple breaks and rearrangements. Sperm incubation in TEST-yolk buffer before microinjection provided more analysable sperm karyotypes with a significantly lower frequency of structural chromosomal abnormalities (39%, P less than 0.001). Our results therefore suggest that sonication induces structural chromosomal abnormalities in spermatozoa. Since the frequency of chromosomal abnormalities after microinjection was higher than after sperm fertilization of hamster eggs, it appears that microinjection per se may also increase the frequency of chromosomal abnormalities in spermatozoa. These results are based on small numbers and must be confirmed on larger sample sizes, but our study suggests that microinjection of spermatozoa into eggs should not be recommended for clinical use until fully evaluated.

Animals↗

PubMed1987

Prediction of traumatic aortic rupture from plain chest film findings using stepwise logistic regression.

We reviewed initial chest radiographs of 21 patients with, and 26 without, aortic rupture, and examined the presence or absence of individual signs previously cited to be associated with aortic rupture. Using stepwise logistic regression, the three most significant signs associated with rupture were loss of aortic contour, tracheal deviation, and mediastinal-to-chest ratio. A formula calculating the probability of aortic rupture (P) using these three variables was derived. Using a low cutoff point, this equation would approach 100% sensitivity in detecting aortic rupture while reducing the number of negative aortographs. The reliability of this equation and the optimal cutoff point must be determined in a prospective study before being used to make clinical decisions.

Aorta↗

PubMed1986

An increased frequency of human sperm chromosomal abnormalities after radiotherapy.

13 cancer patients were studied before radiotherapy (RT) and at regular intervals after RT to determine the effect of RT on chromosomal abnormalities in sperm. The men were 19-47 years old and received testicular radiation doses of 0.4-5.0 Gray. Human pronuclear sperm chromosomes were analysed after penetration of zona-pellucida-free hamster eggs. Unfortunately the hamster egg penetration rates were exceedingly low, both before and after RT and this limited the number of sperm chromosome complements which could be analysed. Before RT, the frequency of abnormal sperm chromosome complements was 0% (0/9). After RT, the majority of men were azoospermic for 24 months but complements could be analysed from 4 men. In the first 12 months the frequency of abnormalities was 13% (1/8) and at 24 months it was 13% (7/55). By 36 months after RT, most men had recovered sperm production and the frequency of abnormalities in 8 men was 21% (18/86), which is significantly higher than the rate in control donors (8.5%). For individual men the range was 6-67%, and there was a significant correlation between testicular radiation dose and the frequency of sperm chromosomal abnormalities. The frequencies of both numerical and structural abnormalities were significantly increased after RT. This is the first evidence that radiation may increase the frequency of chromosomal abnormalities in human gametes.

Adult↗

PubMed1985

A prospective serial study of the effects of radiotherapy on semen parameters, and hamster egg penetration rates.

Cancer patients were studied before radiotherapy (RT) and at regular intervals after treatment (1, 3, 12, 24, 36, 48 months) to determine the effect of radiotherapy on semen parameters and sperm function as assessed by the hamster egg penetration assay. The cancer patients received testicular radiation doses of 0.4 to 5.0 grays (40 to 500 rads). The pre-radiotherapy semen profile varied considerably but in general the profile was poor: 7/11 men had a sperm concentration less than 20 X 10(6)/ml and a total count of less than 50 X 10(6), while the hamster egg penetration rates were also very low with a mean of 5% (range 0% to 15%). This is the first study demonstrating that sperm function as well as sperm concentration is impaired in cancer patients pre-radiotherapy. At 3 and 12 months post-radiotherapy, 8/11 men were azoospermic. By 24 months 8/11 were producing sperm although only 2 had hamster egg penetration rates greater than 15%. All men studied at 36 months (4) and 48 months (3) post-radiotherapy had recovered spermatogenesis but hamster egg penetration rates were still poor. There was a highly significant inverse correlation between testicular radiation dose and subsequent sperm concentration and hamster egg penetration rates.

Adult↗

PubMed1983

Changes in left ventricular dimensions and performance resulting from acute and chronic volume overload in the conscious dog.

A previously described animal model with an aorta to left atrium shunt has been modified to assess changes in left ventricular dimensions and performance resulting from volume overload of the left ventricle and to determine if any of these changes can predict outcome. In eight surviving dogs, end-diastolic and end-systolic diameters and estimated stroke volume increased rapidly in a curvilinear fashion over approximately 60 days with no significant changes thereafter. Mean normalized circumferential fibre shortening velocity was slightly less than and fractional shortening was similar to the controls; the changes in both indices were parallel to those in the controls. In five dogs that died 5-18 days postoperatively in congestive heart failure, none of the measurements obtained could be used to predict the outcome; the changes in the left ventricular diameters were similar to those in the survivors and systolic function was either normal or enhanced.

Animals↗

PubMed1981

Acute and chronic changes after aortic valve damage in the intact dog.

Acute aortic regurgitation was produced under anesthesia in 11 closed-chest dogs previously instrumented with ultrasound transducers. The immediate responses included increases in end-diastolic diameter (EDD), fractional shortening (FS), heart rate, left ventricular end-diastolic pressure (LVEDP), and pulmonary capillary wedge pressure (PCWP), the latter being transient as was a decrease in left ventricular peak systolic pressure (LVSP). End-systolic diameter (ESD) did not change. The grouped data suggest that no further changes occurred following the initial responses except in PCWP and LVSP. The data from individual dogs showed that there was a tendency for EDP, LVEDP, and PCWP to return toward control values after the initial increases in those dogs in which the heart rate increased after valve damage. This suggests that there were ongoing compensatory adjustments after the initial responses in this subgroup. Twelve dogs were followed chronically in the intact conscious state with echocardiographic measurements after acute aortic valve damage. EDD and ESD increased rapidly for about 80 days after which EDD increased slowly, whereas ESD showed no further change. Wall thickness and FS did not change throughout the period of study, suggesting that increasing wall thickness may be a relatively late change and that it may be related to the level of myocardial compensation.

Acute Disease↗

PubMedDate not supplied

The relationship between sperm chromosomal abnormalities and sperm morphology in humans.

It has been suggested that an assay for sperm morphology might prove useful as an initial screen in evaluating men at risk for an increased frequency of sperm chromosomal abnormalities. In this study, the technique for analysis of human sperm chromosomes after penetration of hamster eggs was employed to determine whether there is an association between the frequency of chromosomally and morphologically abnormal sperm. 30 healthy men of proven fertility were studied. The ages of the donors ranged from 22 to 55 years. The analysis was performed "blindly" so that the technician analysing the chromosome spreads had no knowledge of the age of the donors or of the individual frequencies of morphologically abnormal sperm. There was no significant relationship between the proportion of morphologically abnormal sperm and the proportion of chromosomally abnormal sperm when controlled for age. This was true for the total frequency of chromosomal abnormalities and also for numerical and structural chromosomal abnormalities. These results suggest that an assay of morphology is not a good indication of chromosomal normality in human sperm.

Adult↗

PubMedDate not supplied

Whole-abdominal radiation in endometrial carcinoma: an analysis of toxicity, patterns of recurrence, and survival.

PURPOSE: The purpose of this study was to determine the toxicity, patterns of recurrence, and survival in high-risk endometrial cancer patients treated with whole-abdominal radiation. MATERIALS AND METHODS: All patients with endometrial cancer treated at Northwestern University since 1994 and at Rush University since 1993 were retrospectively reviewed. Patients believed to be at high risk for intra-abdominal recurrence and who received whole-abdominal radiation were reviewed for this study. RESULTS: A total of 30 patients completed whole-abdominal radiation (WAR) and were available for study. The mean and median follow-up was 2.3 and 2.1 years, respectively, with a range of 0.13 to 6.1 years. Seventy-eight percent of the cohort received surgical staging with bilateral salpingo-oophorectomy/total abdominal hysterectomy/lymph node sampling. Forty-seven percent of the patients were found to have serous histology as a component of their tumor. Surgical staging results included 19% stage 1B, 4% stage IC, 8% stage IIB, 37% stage IIIA, 26% stage IIIC, and 7% stage IVB. Two patients had gross residual disease at the completion of surgery. Megestrol acetate (Megace) was used as an adjuvant treatment in 37% of patients, and no cases received initial chemotherapy. All patients received WAR with a mean total dose and dose per fraction of 2620 and 143 cGy, respectively. Twenty-two percent of patients received a para-aortic boost. The mean total pelvic dose was 4956 cGy. Seventy percent of patients received a vaginal cuff boost. Eight percent of patients had grade 3 acute gastrointestinal morbidity, and 4% had grade 4 acute gastrointestinal morbidity. No other grade 3 or greater acute or long-term morbidity was noted. At last follow-up, seven (23%) patients had experienced recurrence. The pattern of first recurrence was 0% in the vaginal cuff, 3% other vaginal, 7% pelvic, 7% upper abdominal, 3% lung, 7% bone, and 7% para-aortic lymph nodes. Ultimate recurrences were similar. At last follow-up, 77% patients had no evidence of disease, 13% were alive with disease, and 10% had died of disease. CONCLUSIONS: Utilizing a conservatrive total whole-abdominal radiation dose and limited para-aortic nodal boost resulted in very tolerable treatments. The patterns of recurrence and survival in this early report are encouraging.

Abdominal Neoplasms↗

PubMedDate not supplied

The Activities of Daily Living Questionnaire: a validation study in patients with dementia.

This study describes the development and validation of the Activities of Daily Living Questionnaire (ADLQ), an informant-based assessment of functional abilities, in patients with probable Alzheimer disease and other forms of dementia. The ADLQ measures functioning in six areas: self-care, household care, employment and recreation, shopping and money, travel, and communication. The ADLQ was administered to 140 caregivers followed longitudinally in the Northwestern Alzheimer's Disease Center. In a subset of 28 participants, the total ADLQ score and each of the subscales were found to be highly reproducible, with average concordance coefficients of 0.86. Concurrent validity was established by comparing the ADLQ with the Record of Independent Living, a previously validated measure of level of dependency in daily living activities. The ADLQ was also compared with other measures of dementia severity on the initial and annual follow-up visits and was found to be significantly and negatively correlated with the Mini-Mental State Examination and positively correlated with the Clinical Dementia Rating Scale. The ADLQ has high test-retest and concurrent validity and is consistent with other measures of temporal decline in patients with probable Alzheimer disease and other forms of dementia.

Activities of Daily Living↗