Biomedical subjects

J Newman

Publications and source records attributed to J Newman.

At least 181 records · Page 10Linked to original sources

PubMed1989

Dynamic light scattering measurements of the diffusion of probes in filamentous actin solutions.

The diffusion coefficients of monodisperse polystyrene latex spheres in solutions of polymerized actin were measured using dynamic light scattering. Four different probes with radii R, ranging from 50 to 500 nm, were separately used in actin solutions with concentrations c, ranging from 1.5 to 21 microM, which had been polymerized with either 1 mM MgCl2, 1 mM CaCl2, or 100 mM KCl. Under all conditions, and at four different scattering angles in the range of 30 degrees-90 degrees, the measured average diffusion coefficients D of the probes were systematically smaller for samples of increased actin concentration or of increased probe radius. Control experiments indicated that the probes did not bind to the actin. These data for Mg2+- and Ca2+-polymerized actin agree and were found to be quite well summarized by the scaling relation D/D0 = exp[-alpha R delta c nu], where D0 is the measured diffusion coefficient of the probes in water (and, as also measured, in the starting actin solutions prior to polymerization with added salt), with values of delta = 0.73 +/- 0.05, nu = 1.08 +/- 0.09, and alpha = (1.1 +/- 0.6) x 10(-3) (with c in microM and R in nm). Data for KCl-polymerized actin show much more restricted diffusivities of the probes at comparable actin concentrations. Inhomogeneities in the solution are reflected in the "effective polydispersity" of the probe diffusion coefficients, which depend on local microviscosity differences.

Actins↗

PubMed1989

Probe diffusion in cross-linked actin gels.

The diffusion of monodisperse polystyrene latex spheres (PLS) in column-purified 0.65 mg/mL actin solutions, polymerized with 100 mM KCl in the absence and presence of a cross-linker, actin binding protein (ABP), has been studied using dynamic light scattering. Measurements over a wide range of scattering angles from 90 degrees to 8 degrees, corresponding to inverse scattering vector probing distances of about 40-400 nm, respectively, give a measure of both the fraction of PLS mobile over the probing distance (from the normalized time autocorrelation function amplitude) and the average diffusion coefficient of the mobile PLS. Both 100- and 500-nm diameter PLS are fully mobile in polymerized actin solutions over distances of less than 100 nm, as reported previously (Newman, J., Schick, K. S. & Gukelberger, G. Biophys. J. 53, 573a, and Newman, J., Mroczka, N. & Schick, K. L. Biopolymers, 28, 655-666). At increasing probing distances, or when ABP is added at molar ratios of 1:750 or 1:150, greater fractions of the PLS are immobilized, up to almost 99% at the conditions of a 400-nm probing distance with 500-nm probes and at a ratio of 1:150 added ABP to actin. The degree of immobilization correlated well with the amount of added ABP, the size of the PLS, and the probing distance. At increasing probe distances, as the degree of immobilization increases, the remaining mobile fraction of PLS has an increasing average diffusion coefficient. These results suggest a range of pore sizes in the actin gels with a mean size of a few hundred nanometers.

Actins↗

PubMed1989

Chronic toxicity/carcinogenicity study of trans-anethole in rats.

A chronic feeding study was carried out in rats with trans-anethole. The test substance was administered in the diet to groups (n = 26-78) of 312 male and 312 female Sprague-Dawley rats at concentrations of 0, 0.25, 0.5 and 1% for 117-121 wk. The average intakes of trans-anethole varied from 105-550 mg/kg body weight/day. No apparent treatment-related reactions were noted. The only effect was a transient retardation of body-weight gain. No excess mortality was caused by the treatment. No abnormalities related to treatment were seen on necropsy except for reduced adiposity in the highest dose groups. Haematological assessments did not reveal any changes related to treatment. Histological examination revealed certain non-neoplastic and neoplastic lesions common in older rats. The incidence of some hepatic lesions was significantly higher in some treated groups than in controls: altered cell foci (females of the 1% group), nodular hyperplasia (males of the 0.5% group and males and females of the 1% groups), benign tumours (females of the 1% group) and malignant tumours (females of the 1% group). The results are compared with those of previous investigations. The authors of this study stress that the low incidence of hepatocarcinomas is restricted to a single species and sex and to the highest dose tested. This pattern of species, sex and dose dependency strongly suggests that metabolic and pharmacokinetic studies will be helpful in interpreting the significance of the rat tumours with regard to the safe consumption of trans-anethole by man. The changes observed in this chronic feeding study are not thought to be of genetic origin and consequently trans-anethole does not constitute a significant carcinogenic risk to man. Further studies are in progress to substantiate this conclusion.

Allylbenzene Derivatives↗

PubMed1989

The problem of diabetic renal failure in the United States: an overview.

Native Americans, blacks, and other minorities are at high risk for diabetic renal failure, most of which is caused by non-insulin-dependent diabetes. Many of these patients receive care in publicly supported health programs. Recent evidence of the efficacy of hypertension control in slowing the decline in renal function and our ability to detect those at highest risk for renal deterioration with inexpensive microalbuminuria tests suggest major opportunities for concerted efforts to reduce the incidence of end-stage renal disease. Guidelines for management of high-risk patients are needed to translate effective management strategies into routine clinical practice.

Black or African American↗

PubMed1989

Breastfeeding problems presenting to the emergency department: diagnosis and management.

With more mothers breastfeeding their babies and postpartum stays in hospital becoming shorter, more mothers are presenting to the emergency department with problems that formerly were managed in the newborn nursery. This article deals with an approach to the breastfeeding baby who presents in the emergency department because of jaundice, poor feeding, "colic," gastrointestinal bleeding, and failure to thrive. Although many of these problems also occur in the bottle-feeding baby, only the special considerations which apply to the breastfeeding baby will be considered.

Breast Feeding↗

PubMed1989

The value of NOR numbers in neoplastic and non-neoplastic epithelium of the stomach.

Using a silver staining technique, nucleolar organizer region-associated proteins (AgNORs) have been studied in paraffin sections of 15 benign gastric ulcers, seven early gastric cancers, 13 gastric adenocarcinomas and 10 control cases. A significant difference in the mean number of AgNORs per nucleus was found when control and benign groups were compared with the malignant group. However, there was an overlap between each category. Further studies are warranted to determine if this may be of value in differentiating regenerative epithelium from early malignancy.

Adenocarcinoma↗

PubMed1989

Significance of venous and lymphatic invasion in malignant polyps of the colon and rectum.

Three hundred and sixty seven neoplastic colorectal polyps removed at endoscopy of which 34 were complicated by invasive carcinoma, were reviewed clinically and histologically to assess the prevalence and clinical significance of venous and or lymphatic invasion. Traditional stains for histological assessment were supplemented by immunohistochemical methods. Venous and or lymphatic invasion was present in six cases (17.6%), with a statistically significant association with recurrent carcinoma or Dukes's C carcinoma in polyps otherwise regarded as completely excised. The presence or absence of venous and or lymphatic invasion in malignant polyps should be documented as if present, further treatment is indicated. A combination of haematoxylin and eosin and elastic-van Gieson stains will usually identify the presence of vascular invasion. Where a discrepancy arises, however, additional immunohistochemical stains may be of value.

Colon↗

PubMed1989

Malignant carcinoid tumour of the oesophagus.

A patient with a carcinoid tumour of the oesophagus developed widespread metastases within three years of a successful local resection. Of the seven patients with oesophageal carcinoid tumours so far reported, four have died with widespread metastases.

Aged↗

PubMed1989

Removal of viral contaminants by monoclonal antibody purification of plasma proteins.

The transmittance of pathogenic viruses by the widespread administration of protein fractions such as F VIII prepared on a large scale from pooled human plasma has been of growing concern. We have now demonstrated that significant amounts of pathogenic viruses including LAV/HTLVIII may be removed by a new large scale fractionation process for the preparation of human F VIII (Monoclate) which employs immunoaffinity chromatography. Model viruses representative of different virus families and the LAV strain of HIV were added to cryoprecipitate and then the mixture was processed as for Monoclate manufacturing. Virus titers were determined at each step of the fractionation procedures. An overall reduction of at least 6 logs was obtained for the model viruses and the HIV due to the purification process. An added heating step further increased the safety margin for the product resulting in at least an overall reduction of 7-9 logs for HIV. Clinical experience with Monoclate in virgin hemophiliacs has confirmed its viral safety. Our laboratories are exploiting a similar strategy of immunoaffinity chromatography to ensure the viral safety of FIX and protein C preparations derived from plasma.

Antibodies, Monoclonal↗

PubMed1989

Nucleolar organizer regions in transitional cell tumors of the bladder.

The traditional silver staining technique that identifies nucleolar organizer region-associated proteins has recently been adapted and applied to paraffin sections, and used to examine changes in nucleolar organizer region numbers in a variety of benign and malignant conditions. We describe herein the enumeration of nucleolar organizer regions in a variety of benign and malignant conditions of the transitional epithelium of the urinary bladder. While there is a statistical separation between normal and neoplastic groups, there is a degree of overlap between normal, inflammatory, dysplastic, and neoplastic urothelium.

Carcinoma in Situ↗

PubMed1989

The fine structure of the human fetal urinary bladder. Development and maturation. A light, transmission and scanning electron microscopic study.

The urinary bladders of 27 human fetuses, aged 7 weeks to full term, were studied by light, transmission and scanning electron microscopy to establish the sequence of events in the development and maturation of the organ during fetal life. In the early specimens, 7-12 weeks old, the urinary bladder was lined by a bilayered, cuboidal and glycogen-rich epithelium. During the 13-17th weeks the epithelium thickened, a third layer developed and by light microscopy it now resembled urothelium. By 21 weeks this had evolved into a 3-4 layer thick epithelium with typical ultrastructural urothelial characteristics. Smooth muscle cells emerged from the condensed mesenchyme of the bladder wall by the 12th week of gestation, initially in the cephalic part of the organ but spreading within a week into the caudal end. Our findings indicate that the human fetal bladder undergoes a series of vital developmental changes during 13-21 weeks of gestation finally acquiring the typical urothelial lining and a well-developed muscular coat.

Embryonic and Fetal Development↗

PubMed1989

Pneumatosis cystoides intestinalis. Histological mucosal changes mimicking inflammatory bowel disease.

In 10 cases of pneumatosis cystoides intestinalis affecting the colon in adults, the overlying mucosa exhibited abnormal glandular architecture. The importance of this feature lies in the possible confusion histologically with inflammatory bowel disease, especially Crohn's disease.

Biopsy↗

PubMed1988

Rheology of G-actin solutions.

Recent reports that dilute solutions of G-actin form viscoelastic gels have been investigated using several experimental variations of three distinct physical techniques in independent laboratories. Direct measurement of storage and loss moduli were made using two rheometers of different design. Measurements of the diffusion of G-actin and of tracer particles added to G-actin solutions were carried out using dynamic light scattering and fluorescence photobleaching recovery techniques. Measurements were performed over a period of many hours, on actin solutions prepared under conditions for which anomalous gelation had been reported. All data from this investigation are consistent with the conclusion that dilute G-actin solutions behave as newtonian liquids.

Actins↗

PubMed1988

Ambulatory 24 hour sleep-wake monitoring in narcolepsy-cataplexy compared to matched controls.

Twenty-four hour ambulatory sleep-wake recordings were made in 10 untreated patients with narcolepsy-cataplexy and 10 matched controls. Nocturnal sleep of narcoleptics was similar to descriptions of laboratory based recordings and was characterized by frequent sleep onset REM periods, high variability of REM latency, increased amounts of wakefulness after sleep onset, and low sleep efficiencies. Daytime portions in narcoleptics showed greater drowsiness and sleep than in controls with significantly higher amounts of stages 1A, 1B, 3, 4 and REM, more sleep episodes longer than 1 and longer than 10 min in duration, and high intersubject variability. On average, only 1.2 daytime sleep episodes began with sleep onset REM periods. There was a strong tendency in both groups towards a long mid-afternoon sleep episode often containing slow wave sleep (SWS) and which was significantly longer in narcoleptics. The mean interval between the onset of nocturnal SWS and the main daytime SWS peak was 14.1 h for narcoleptics and 13.6 h for controls. Daytime waking portions in narcoleptics showed significantly less 'active wakefulness' than in controls. There was no correlation between MSLT measures of sleepiness and amount of daytime sleep in ambulant recordings.

Adult↗

PubMed1988

Ultrasound-guided fine-needle histological biopsies in the abdomen.

The results of 83 consecutive ultrasound-guided abdominal fine-needle biopsies are reviewed and the technique described. Material suitable for histological examination was obtained in 87% of cases. The overall sensitivity for the diagnosis of malignancy was 82% and the overall accuracy was 86%. The predictive value of a positive result was 100%. Of the biopsies positive for malignancy, 61% provided further descriptive histological information, usually allowing a differential diagnosis, and in 35% of the positive biopsies a specific histogenesis or diagnosis was suggested. There were no complications with this procedure. This technique was found to be of value for the diagnosis of abdominal lesions and is recommended where there is no cytology service available. The technique has certain advantages over aspiration cytology and could prove to be superior.

Abdominal Neoplasms↗

PubMed1988

Gastric adenocarcinoma associated with adenomyoma of the stomach.

We report a case of gastric adenomyoma contiguous with adenocarcinoma of the stomach. Although a similar association is well recognized in the duodenum, we believe this to be the first documented case in the stomach. We review the literature on adenomyomata and discuss the implications of this finding. It would appear that glandular and cystic intramural lesions of the stomach are a heterogeneous group, and while there is a well established association between gastric carcinoma and gastritis cystica profunda, the same does not apply to gastric adenomyoma.

Adenocarcinoma↗

PubMed1988

Ectopic production of beta-human chorionic gonadotropin by inverted papilloma of the nose.

A series of 19 inverted papillomas (transitional type or Schneiderian papillomas) of the nose were examined using an immunogold-silver (IGS) technique and an indirect immunoperoxidase technique. We demonstrated beta-HCG production in all 19 specimens with both methods. The staining demonstrated by the IGS technique was of a greater intensity and in a larger number of cells than that observed by the indirect immunoperoxidase method.

Adult↗

PubMed1988

Scanning electron microscopy of the upper urinary tract in transitional cell carcinoma of the renal pelvis.

Three nephrectomy specimens with transitional cell carcinoma (TCC) of the renal pelvis were thoroughly examined by both light and scanning electron microscopy. The tumours as well as the urothelium of the upper urinary tract were studied. In all three cases, extensive areas of the urothelium, even in places remote from the tumours, were found by scanning electron microscopy (SEM) to be covered by pleomorphic microvilli. This suggests that there is a widespread failure of differentiation of the urothelium to a much greater extent than can be appreciated by conventional light microscopy.

Adult↗