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Biomedical subjects

K Roberts

Publications and source records attributed to K Roberts.

At least 163 records · Page 9Linked to original sources
PubMed1987

Detection of fetal movement using Doppler ultrasound.

Using conventional cardiotocographic equipment with the ultrasound transducer placed to detect the fetal heart, we obtained unprocessed Doppler signals in the frequency range 13-70 Hz and used them to detect movements of the fetal trunk. In an assessment of maternal perception of fetal activity, we found that Doppler signals were associated with 739 of 780 appreciated movements (95%); however, 36% of all the Doppler signals were unaccounted for. A separate comparison of the Doppler signals against real-time ultrasound observations of fetal activity showed that 913 of 970 visualized trunk movements (94%) were associated with Doppler signals. Other Doppler signals were found to be due principally to fetal breathing and fetal hiccups. Appropriate processing of the Doppler signals obtained during antenatal cardiotocography may allow an objective assessment of fetal activity to be added to the fetal heart rate recording.

Female↗
PubMed1987

Automated three-part leukocyte differential counts in the preoperative evaluation of ambulatory surgery patients.

The clinical value of the Coulter S-Plus V three-part leukocyte differential cell count in the preoperative evaluation of 295 patients scheduled for ambulatory surgery was examined. Ninety-five percent of the specimens could be processed by the instrument without further review. Only 11 specimens had abnormal manual differential cell counts. Of these, all but three were detected using a combination of S-Plus V-generated flags and preset laboratory criteria. There were 16 cases with red blood cell morphologic abnormalities, eight of which were not associated with specimens referred for complete manual differential cell count. In none of these 11 unreferred cases was the undetected abnormality of clinical significance relative to the patient's upcoming surgery. The use of the S-Plus V three-part differential in this patient population can result in a significant cost savings without adversely affecting patient care.

Ambulatory Surgical Procedures↗
PubMed1986

Purification and characterization of a sulfated glycoprotein secreted by Sertoli cells.

Sulfated glycoprotein 2 (SGP-2), the major secretion product of Sertoli cells, was purified from cell culture medium by reverse-phase high-performance liquid chromatography. The native protein consists of disulfide-linked monomers of 41,000 and 29,000 daltons which have a strong tendency to associate into multimers. The purified SGP-2 was subjected to amino acid analysis and contained high levels of Asx (11.1%), Glx (15.1%), and leucine (11.5%). The oligosaccharides on the purified SGP-2 were analyzed to determine the monosaccharide compositions and the molecular weights of the intact carbohydrate moieties. SGP-2 was shown to be 23.7% carbohydrate and consisted of 1% fucose, 3.5% mannose, 4.1% galactose, 7.1% N-acetylglucosamine, and 8.0% N-acetylneuraminic acid. No N-acetylgalactosamine was detected. When the SGP-2 was digested with proteases, the intact oligosaccharides were chromatographed over a Bio-Gel P-6 column and found to elute in a single symmetrical peak of approximately 3,300 g/mol. On the basis of these results, the oligosaccharides on SGP-2 were proposed to consist of triantennary chains similar to those found on fetuin. When the 35SO4(2-)-labeled SGP-2 was digested with Pronase, the free amino acids could be separated by chromatography from the oligosaccharide. The 35SO4(2-) was shown to be associated with the oligosaccharide portion of SGP-2.

Amino Acids↗
PubMed1986

Morphological measurement of the SEP using a dynamic time warping algorithm.

A dynamic time warping technique was created to align the components of digitally high-pass (300 Hz-2500 Hz) filtered somatosensory evoked potentials evoked by median nerve stimulation recorded with a bipolar cephalic montage. A cost function was assigned related to the amount of warping necessary to match a standard wave derived from 24 normal subjects. Its value ranged from 0.525 to 2.456 (mean 1.305 +/- 0.501). This contrasted with a mean of 5.089 +/- 4.277 (range 0.701-13.972) derived from 25 patients with definite (n = 24) or possible (n = 1) multiple sclerosis chosen on the basis of having few or no clinical abnormalities at the time of testing. Fourteen (56%) of the patients had cost functions that were 3 or more S.D.s above the normal mean as compared to 3 (12%) having prolonged latency of the N19 peak. When used in combination, the cost function and latency yielded 60% abnormalities; 5 times higher than latency measurement alone.

Adult↗
PubMed1986

Carney's triad: gastric leiomyosarcoma, pulmonary chondroma and extra-adrenal paraganglioma in young females.

The case of a 13-year-old girl with a gastric leiomyosarcoma and a pulmonary osteochondroma is presented. The association of these two tumours and extra-adrenal paraganglioma has been described as a triad by Carney. The patient is free of recurrence of the gastric tumour with no evidence of paraganglioma 10 months after the operation. To our knowledge this is the first case of the triad reported in the UK.

Adolescent↗
PubMed1985

A clonal analysis of human peripheral blood lymphocytes displaying natural killer-like activity.

Human Fc gamma receptor-bearing lymphocytes and T cells, prepared by sorting peripheral blood lymphocytes using the B73.1 monoclonal antibody, have been cloned by limiting dilution. Although quiescent lymphocytes of either cell type were unresponsive to interleukin 2 (IL 2), following induction with phytohemagglutinin and/or the BSM B lymphoblastoid cell line they could be expanded in IL 2 utilizing a mixed irradiated feeder system. Clones originating from B73.1+ lymphocytes displayed a characteristic large granular lymphocyte (LGL) morphology but were otherwise functionally and phenotypically heterogeneous. Of 36 clones analyzed 19 displayed significant natural killer (NK)-like activity, each clone having a target cell repertoire identical to uncloned NK effectors. Furthermore, only a minority of clones (i.e. 5) displayed significant antibody-dependent cellular cytotoxicity, while levels of lectin-induced cellular cytotoxicity were normally commensurate with a clones level of NK-like activity. No correlation was evident between the phenotype of a clone and its cytotoxic activity since of 12 cytotoxic clones phenotyped, 8 expressed the OKT3 antigen but lacked the B73.1 antigen; 2 lacked the OKT3 antigen but expressed the B73.1 antigen and one lacked both OKT3 and B73.1 antigens. In addition the expression of OKT8 and OKT4 antigens was not in any way predictive of the cytotoxic capacity of a given clone. Several clones expressing T cell associated antigens bore a phenotype that distinguished them from T cell clones insofar as T cell subset antigens were expressed in the absence of the OKT3 antigen and vice versa.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1985

Gastrin release from dispersed gastrinoma cells: effects of calcium and calcium ionophore (A23187).

Dispersed single-cell suspensions of human gastrinoma tissue were incubated for 15, 60, and 120 min in a calcium-containing medium, (0.1, 2, 10 mM) in calcium-free medium and in calcium-free medium containing the calcium ionophore A23187 (0.01, 1, and 100 micrograms/ml). Supernatant and pellet (intracellular) gastrin levels were determined by radioimmunoassay. Supernatant gastrin levels remained stable over 120 min in calcium chloride or calcium gluconate containing medium, while intracellular pellet gastrin approximately tripled during the same incubation period. Total gastrin (supernatant plus pellet) approximately doubled during the 2-hr incubation in calcium. However, calcium (0.1, 2, or 10 mM) failed to produce a dose-dependent rise in supernatant, pellet, or total gastrin when compared to calcium-free incubates. Contrary to the expected gastrin response to calcium, supernatant and pellet gastrin levels were higher in incubates in calcium-free medium than in calcium-containing incubates. A23187 (0.01 or 1 mcg/ml) in a calcium-free medium decrease supernatant gastrin while high dose ionophore (100 mcg/ml) increased supernatant gastrin. All doses of ionophore stimulated pellet and total gastrin levels. Thus, it appears that the clinical augmentation of gastrin levels, seen with calcium challenge in vivo may not be solely due to changes in serum calcium.

Adult↗
PubMed1985

Cell wall glycoproteins: structure and function.

Hydroxyproline-rich glycoproteins form an important, but little understood, structural component of most cell walls. Their occurrence, chemistry, synthesis, secretion, cross-linking and functions in higher plant cell walls will be briefly reviewed. Similar molecules also occur in other groups of plants; in particular, in the algae. In many of these they form highly ordered cell surface arrays, and we have studied these by high-resolution electron microscopy and computer image reconstruction. Some resulting three-dimensional models of these are presented. One particular glycoprotein, the major structural component of the cell wall of Chlamydomonas reinhardii, has been investigated in some detail. The chemistry and structure of this glycoprotein, which we have called volvin, has been studied and a family of monoclonal antibodies has been raised against it. Some of these antibodies appear to be specific to oligosaccharide side-chains and allow the localization of these substituents and their sites of synthesis. Immunofluorescence studies have shown that the expression of some of these antigenic determinants is developmentally regulated or cell-cycle-dependent. Immunogold labelling of thin sections has enabled the sites of synthesis and the method of secretion to be determined. These results will be discussed in the context of other cell wall glycoproteins, their relation to other glycoproteins, such as the mating agglutinin, and to their possible functions.

Cell Wall↗
PubMed1984

Polyneuropathy in Waldenström's macroglobulinaemia: reduction of endoneurial IgM-deposits after treatment with chlorambucil and plasmapheresis.

A case of progressive polyneuropathy associated with Waldenström's macroglobulinaemia is reported. A monoclonal IgM-lambda gradient was detected in the serum and cerebro-spinal fluid. By electro-immunoblot analysis antibodies against myelin-associated glycoprotein were found in the serum and cerebro-spinal fluid. The motor and sensory conduction velocities of several peripheral nerves were markedly decreased, and examination of visual evoked potentials (VEPs) revealed pathological latencies. Sural nerve biopsies before and after treatment with chlorambucil and plasmapheresis showed nerve fibre loss and demyelination. In the pre-treatment biopsy, heavy accumulations of filamentous material were found which stained positively for IgM by immuno-cytochemistry. Such accumulations had disappeared in a biopsy performed after treatment. The morphological findings were correlated with an improvement of clinical and electro-physiological findings.

Chlorambucil↗
PubMed1984

Monoclonal antibody screening: two methods using antigens immobilized on nitrocellulose.

The dot-immunobinding assay of Hawkes et al. [R. Hawkes, E. Niday, and J. Gordon (1982) Anal. Biochem. 119, 142-147] has been modified such that many antibody solutions are screened simultaneously on dots of antigen applied to a single sheet of nitrocellulose using very small amounts of both antigen and antibody solutions. This method is also used in the assay of antibody binding on dots of components of the antigen after enzymatic digestion and chromatographic fractionation and to dots of compounds which may be chemically related to the antigen. An aluminum template for screening Western blots with a number of different antibody solutions on a single sheet of nitrocellulose is also described. Possible applications of the dot-immunobinding assay in screening for virus are discussed.

Animals↗
PubMed1984

Questions regarding the sequential neural generator theory of the somatosensory evoked potential raised by digital filtering.

Digital bandpass filtering (300-2500 Hz) designed for zero phase shift was applied to somato-sensory evoked potentials recorded with cephalic bipolar montages. Four consistent negative and corresponding positive peaks with latencies of about 16, 18, 19, and 20 msec were elicited with median nerve stimulation. Peroneal nerve stimulation also elicited 4 reproducible negative-positive peaks having latencies of about 24, 26, 28, and 30 msec. Interpeak latencies measured 1.3 +/- 0.2 msec and 1.8 +/- 0.25 msec for median and peroneal elicited SEPs respectively. Because cephalic bipolar recordings cancel most far-field potentials, multiple generators cannot account for all the additional components seen. It is hypothesized that some of the high frequency components recorded are due to activity in recurrent intrathalamic neuronal networks.

Adult↗
PubMed1984

Influence of lectin-free interleukin-2 on natural and antibody-dependent cellular cytotoxicity.

Supernatants derived from MLA-144, a gibbon T cell line that constitutively releases interleukin-2 (IL-2) and which lack detectable interferon (IFN) had the capacity to enhance the natural killer (NK) cells function of human peripheral blood lymphocytes. Percoll fractionation revealed that like IFN-inducible cytotoxic cells lymphocytes responding to MLA-144 supernatants cofractionate with native NK cells. Exposure to MLA-144 conditioned medium also potentiated the cytotoxic capacity of extravascular effector cells which are either unresponsive or weakly responsive to interferon-alpha (IFN-alpha). Moreover lymphocyte (K cell)-mediated antibody-dependent cellular cytotoxicity (ADCC) which is unresponsive to IFN-alpha was in most cases subject to a modest potentiation following treatment with MLA-144 supernatants. These data confirm previous reports that IL-2 can regulate peripheral blood NK cell function and also demonstrate that this lymphokine can also influence those natural cytotoxic mechanisms which are unresponsive to IFN-alpha.

Animals↗