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Biomedical subjects

J M Barrett

Publications and source records attributed to J M Barrett.

At least 19 recordsLinked to original sources
PubMed1998

Identification of the in vivo promoters of bacteriophages S13 and phi X174 and measurement of their relative activities.

Regions of bacteriophages phi X174 and S13 that contain putative promoter sequences were amplified by the polymerase chain reaction (PCR) and cloned into the reporter vector pKO-1. Assays of galactokinase activity revealed in vivo promoter activity in those constructs containing the promoter sequences with transcription initiation (+1) sites at nucleotide positions 45, 982, 1823, and 5211. These were identical in location to sequences with in vitro promoter activity and to the three known promoters PA, PB, and PD. P5211 is the location of a new, fourth, promoter. A site with a +1 position at nucleotide 4876, previously shown to initiate RNA synthesis in an in vitro run-off transcription assay, had no in vivo promoter activity. To investigate whether flanking sequences had effects on promoter activity, restriction fragments of phi X174 and S13 that encompass the in vivo promoters were cloned into the reporter vector pKO-1. The PA and P5211 promoter constructs showed dramatic effects with increases in activity of up to 7 times that shown with the PCR-generated promoter constructs. The phi X174 PB promoter construct had a 50% decrease in activity compared with the PCR-generated PB clone. While the data showed that in most instances promoter activity is affected by the flanking sequences in which the promoter is embedded, no general pattern correlating flanking sequences and promoter activity could be discerned. Additional evidence that the promoter sequence regions were active in vivo promoters was obtained by S1 nuclease mapping experiments. Initiation of RNA synthesis was shown at positions 45, 982, and 5211.

Bacteriophage phi X 174↗
PubMed1995

Computer graphics of SEM images facilitate recognition of chromosome position in isolated human metaphase plates.

There is general agreement that at the time of mitosis chromosomes occupy precise positions and that these positions likely affect subsequent nuclear function in interphase. However, before such ideas can be investigated in human cells, it is necessary to determine first the precise position of each chromosome with regard to its neighbors. It has occurred to us that stereo images, produced by scanning electron microscopy, of isolated metaphase plates could form the basis whereby these positions could be ascertained. In this paper we describe a computer graphic technique that permits us to keep track of individual chromosomes in a metaphase plate and to compare chromosome positions in different metaphase plates. Moreover, the computer graphics provide permanent, easily manipulated, rapid recall of stored chromosome profiles. These advantages are demonstrated by a comparison of the relative position of group A-specific and groups D- and G-specific chromosomes to the full complement of chromosomes in metaphase plates isolated from a nearly triploid human-derived cell (HeLa S3) to a hypo-diploid human fetal lung cell.

Cells, Cultured↗
PubMed1992

The efficacy and safety of the cytobrush during pregnancy.

The safety and efficacy of abrasive cytology, using the cytobrush, were evaluated in 300 pregnant patients. When compared to conventional cytology obtained with a cotton-tipped applicator there was no difference in adverse pregnancy events. Smear adequacy (containing endocervical cells) was statistically (P less than 0.01) and clinically increased from 21 to 86%. The use of abrasive cervical cytology was associated with a twofold increase in the incidence of abnormal smears.

Adult↗
PubMed1992

Split course interstitial brachytherapy with a source shift: the results of a new technique for salvage irradiation in recurrent inoperable cervical lymphadenopathy greater than or equal to 4 cm diameter in 23 patients.

Between June 1981 and December 1986, 23 patients with prior irradiation of the neck for epithelial ENT tumors underwent salvage irradiation for isolated recurrent inoperable cervical lymphadenopathy greater than or equal to 4 cm. The initial irradiation had delivered 45-80 Gy to the cervical lymph nodes. Split course interstitial brachytherapy was used with a source shift in an attempt to decrease treatment complications. The first and second course of the split course implants delivered 35 Gy and 30 Gy at a 1 month interval. The active lines of the second implant were placed parallel to and in between the position of the lines of the first implant. Three patients did not receive the second implant (one death, one disease evolution, one necrosis). For the patient who died between the first and second implants the local control rate could not be determined. The immediate overall local control rate was 73% (16/22) with a later recurrence rate of 62% (10/16), but only in three cases was recurrence within the treated volume (19%-3/16). The local control rate was better (3/9) if the initial lymphadenopathy was greater than or equal to 4 cm less than or equal to 6 cm but worse (3/13) in those with initial lymphadenopathy greater than 6 cm. Survival of these patients overall was poor with 26% survival at 1 year and 13% at 2 years. Tolerance overall was acceptable with tissue necrosis occurring in 36.5% of cases including those with initial skin involvement. If these cases were excluded the necrosis rate was only 15.5%. In this patient population with inoperable recurrent cervical lymphadenopathy in whom a further dose of external irradiation is not possible interstitial brachytherapy should be considered. Our technique of implantation, split over two sessions with a source shift, is practicable with an acceptable toxicity. It may be used even after high dose external beam irradiation and in large volumes of disease, and it gives better results than classical brachytherapy.

Aged↗
PubMed1991

Funic reduction for the management of umbilical cord prolapse.

The current management of umbilical cord prolapse centers on attempts to alleviate the pressure of the presenting part on the cord while preparation for cesarean section is being made. A 10-year experience in which there were vigorous attempts to accomplish safe vaginal delivery after the diagnosis of umbilical cord prolapse is presented. Eight cases of umbilical cord prolapse occurred, a frequency of 1 in 277 deliveries (0.37%), all of which had a normal immediate neonatal outcome. Vaginal delivery was accomplished in seven patients (87.5%); diagnosis was made in two of them when delivery was imminent. Five patients were more remote from delivery and had successful funic reduction (manual replacement of the prolapsed cord). Funic reduction is proposed as a potentially beneficial initial step in the management of umbilical cord prolapse.

Adolescent↗
PubMed1991

Evaluation of obstetric ultrasonography at the first prenatal visit.

A prospective study was performed on 1000 consecutive patients to assess the value of ultrasonography at first prenatal visit. Significant ultrasonographic findings were noted in more than one third of the patients. A discrepancy between ultrasonography and menstrual dating was the most frequently noted abnormality, occurring in 27%; 59% of those would not have been discovered on initial physical examination. Other frequently noted abnormalities included missed abortion (5.7%) and twins (1.6%). The frequency of abnormalities on the initial laboratory studies recommended by the American College of Obstetricians and Gynecologists was evaluated and found to be significantly less than the frequency of clinically important ultrasonographic findings, ranging from 4.0% for positive urine cultures to 0.2% for positive serologic tests. Unexpected findings on physical examination, excluding assessment of pregnancy dating on the basis of uterine size, were even less frequent, occurring in 2.1% of the patients. It is concluded that obstetric ultrasonography at the time of the first prenatal visit is better than physical examination in evaluating the status of the pregnancy and should be considered for all patients.

Abortion, Spontaneous↗
PubMed1991

Differential expression of c-myc and H-ras oncogenes in Barrett's epithelium. A study using colorimetric in situ hybridization.

To determine the role of c-myc and H-ras in progressive, dysplastic Barrett's mucosa (BM), and the usefulness of these oncogenes as markers for dysplastic lesions at high risk for malignant transformation, sequential formaldehyde solution-fixed, paraffin-embedded biopsy specimens that were obtained from 12 patients with BM were evaluated by in situ hybridization with the use of biotinylated complimentary DNA probes. Nine of the patients were taken from a previous prospective study. Four of these nine patients had dysplasia, and adenocarcinoma had developed in two of them; five had nondysplastic BM only. Two additional patients had adenocarcinoma, but their initial biopsy specimens had revealed dysplasia. One additional patient had intermediate-grade dysplasia. The intensity of oncogene expression was quantified by computerized color-image analysis. Enhanced c-myc expression of approximately equal intensity was consistently observed in all grades of dysplasia and carcinoma. H-ras was also consistently expressed in higher grades of dysplasia and carcinoma but not in low-grade dysplasia. Neither c-myc nor H-ras expression was detected in nondysplastic BM. The expression of H-ras in dysplastic BM appears to be a helpful marker for identifying which dysplastic lesions will progress to carcinoma.

Chronic Disease↗
PubMed1990

Continuous or interrupted fascial closure: a prospective evaluation of No. 1 Maxon suture in 402 gynecologic procedures.

During a 14-month period of using a long-term absorbable suture (No. 1 Maxon), 402 patients were entered into a prospective, randomized trial of fascial closure. Patients were randomized between a continuous closure (201 patients) and an interrupted en bloc (201 patients) technique. Each patient was subjected to a preoperative and intraoperative protocol for wound management. There were no acute wound failures. Wound infection rates and risk of hernia were not apparently affected by closure technique.

Adult↗
PubMed1990

Single-dose antibiotic prophylaxis for patients undergoing extended pelvic surgery for gynecologic malignancy.

The comparative efficacy of single-dose antibiotic prophylaxis was retrospectively evaluated in 116 patients undergoing extended pelvic surgical procedures with curative intent. During the 24-month period, other important variables such as surgeon's experience, duration of preoperative hospitalization, preoperative preparation, method of hair removal, suture type, suture size, use of drains, use of cautery, and abdominal closure were controlled. The overall surgical site infection rate was 4.3% after radical hysterectomy with lymphadenectomy and 4.5% after total hysterectomy with lymphadenectomy. In this clinical situation the use of a single dose of antibiotic prophylaxis theoretically decreases cost and patient exposure and appears to be as efficacious as a multiple-dose regimen.

Anti-Bacterial Agents↗
PubMed1989

Immunocytochemical study of ras and myc proto-oncogene polypeptide expression in the human menstrual cycle.

The human endometrium is a unique and dynamic tissue model system characterized by cyclic processes of cellular proliferation, differentiation, and menstrual desquamation. Both the glandular epithelial and stromal mesenchymal components work in synchronous response to the mitogenetic effect of estradiol and the antimitogenetic effect of progesterone. Mechanisms whereby estradiol and progesterone exert their effects are not completely understood. This study was undertaken to evaluate the expression and localization of the polypeptide products of the ras and myc proto-oncogenes sequentially during the menstrual cycle. Sixteen endometrial biopsy specimens were evaluated. Immunocytochemical quantitation of ras and myc expression was done by use of color image analysis (CoreScan). There was no cyclic variation in the ras polypeptide product, but the expression of myc polypeptide was low in the secretory phase and high in the proliferative phase.

Cell Division↗
PubMed1989

Immunocytochemical study of transforming growth factor expression in benign and malignant gliomas.

Immunocytochemical studies using polyclonal antibodies to epidermal growth factor (EGF) and transforming growth factor (TGF) alpha and beta were performed on 20 cases of human gliomas. EGF immunoreactive material was detected in both benign and malignant glial tumors. In addition, EGF immunoreactive material was detected in normal brain. TGF-beta was detected in both benign and malignant tumors, but was not detected in normal brain. In contrast, TGF-alpha was highly conserved in its expression, occurring predominantly in malignant compared with benign or normal brain tissue (P less than 0.0001). In malignant gliomas, glioblastomas contained 76% TGF-alpha reactivity (immunoreactive product), and anaplastic types contained 85% reactivity. Benign gliomas contained only 13% TGF-alpha reactivity. These findings support the role of TGF-alpha as an oncoprotein marker in brain neoplasms.

Brain Neoplasms↗
PubMed1987

Rat urinary kallikrein localization in kidney: effects of fixation.

The influence of fixation on the immunocytochemical localization of tissue kallikrein in the kidney has been evaluated using both monoclonal and polyclonal antibodies. These studies have provided several results relevant to kallikrein localization in kidney: (1) the intensity and distribution of immunostaining with both polyclonal and monoclonal anti-kallikrein antibodies is fixation-dependent; (2) the most intense and consistent localizations of kallikrein are in the connecting tubule and the cortical collecting duct of the nephron; (3) kallikrein-like immunoreactivity is seen in proximal tubules with polyclonal but not with non-cross-reactive monoclonal antibodies; and (4) fixatives which disrupt membranes reveal a kallikrein-like antigen in straight tubules of the outer medulla. However, immunostaining with monoclonal antibodies indicates that much of the observed immunostaining at this site probably represents cross-reactivity with another member of the kallikrein family of enzymes.

Animals↗
PubMed1985

Plasma 6-keto prostaglandin F1 alpha and thromboxane B2 in sick preterm neonates.

To determine if vascular abnormalities in preterm neonates might be related to vasoactive prostaglandins, stable prostacyclin (6-KPGF1 alpha) and thromboxane A2 (T X B2) metabolites in arterial blood were measured at less than or equal to 6 hours after birth and at 24, 48, and 72 hours using a radioimmunoassay. Neonates of less than 32 weeks gestation (N = 26) were diagnosed as having either the idiopathic respiratory distress syndrome (IRDS, N = 15) or pulmonary edema (PE, N = 11), and were also grouped according to the presence or absence of intracranial hemorrhage (ICH, N = 11) or patent ductus arteriosus (PDA, N = 10). Initial plasma 6-KPGF1 alpha was greater in neonates with ICH (0.23 +/- 0.04 ng/ml, mean +/- SE) than without ICH (0.11 +/- 0.04, p less than 0.05). Neonates with both ICH and IRDS (N = 8) had significantly elevated T X B2 at all sampling times compared to neonates with IRDS and no ICH (N = 7). Both T X B2 and 6-KPGF1 alpha increased with time in those with major ICH. Among neonates without ICH, 7 with IRDS had higher initial 6-KPGF1 alpha (0.19 +/- 0.07 ng/ml) and lower T X B2 (0.15 +/- 0.04 ng/ml) than 8 with PE (0.04 +/- 0.01 and 0.37 +/- 0.09 ng/ml, respectively). The initial 6-KPGF1 alpha (0.024 + 0.003 ng/ml), measured in neonates with PE and without PDA or ICH (N = 6), was significantly less than the corresponding value in the other neonates (0.201 +/- 0.036 ng/ml) (N = 20).

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Physiological and morphological responses of the rat kidney to reduced dietary protein.

Renal physiological and morphological adjustments to a reduced protein diet were studied in young Munich-Wistar rats. Two groups of animals were used for the correlative physiological-morphological studies: normal protein (NP, 24% dietary protein) rats and reduced protein (LP, 8% dietary protein) rats. Both groups were fed their respective diets for 4-5 wk and had free access to drinking water. Physiological measurements of GFR and urea clearance were made on five animals from each group. These data showed that the changes in renal function specifically and almost exclusively affected the handling of urea. There was no difference in GFR between the NP and LP rats. Urea clearance was substantially reduced in LP rats. Morphological analyses were made on perfusion-fixed kidneys of five animals from each group. Selected slices were examined and photographed by light and electron microscopy. These data showed no difference in size and number of elements within the vascular bundles but showed significantly smaller lumina of the thin limbs of the short-looped nephrons and a significant thinning of the wall of the thin descending limbs of the long-looped nephrons. These morphological changes may in part be responsible for the observed physiological adjustments to a reduced protein diet. An additional group of rats (6 NP and 5 LP, all dehydrated) were analyzed for distribution of solutes within the inner medulla. The data showed that the concentration of urea, but not that of Na+, was reduced at the papillary tip in LP rats.

Adaptation, Physiological↗