Biomedical subjects
M Jones
Publications and source records attributed to M Jones.
Towards an understanding of position effect variegation.
Most variegating position effects are a consequence of placing a euchromatic gene adjacent to alpha-heterochromatin. In such rearrangements, the affected locus is inactivated in some cells, but not others, thereby giving rise to a mosaic tissue of mutant and wild-type cells. A detailed examination of the molecular structure of three variegating white mottled mutations of Drosophila melanogaster, all of which are inversions of the X chromosome, reveals that their euchromatic breakpoints are clustered and located approximately 25 kb downstream of the white promoter and that the heterochromatic sequences to which the white locus is adjoined are transposons. An analysis of three revertants of the wm4 mutation, created by relocating white to another euchromatic site, demonstrates that they also carry some heterochromatically derived sequences with them upon restoration of the wild-type phenotype. This suggests that variegation is not controlled from a heterochromatic sequence immediately adjacent to the variegating gene but rather from some site more internal to the heterochromatic domain itself. As a consequence of this observation we have proposed a boundary model for understanding how heterochromatic domains may be formed. It has been recognized for many years that the phenotype of variegating position effects may be altered by the presence of trans-acting dominant mutations that act to either enhance or suppress variegation. Using P-element mutagenesis, we have induced and examined 12 dominant enhancers of variegation that represent four loci on the second and third chromosomes. Most of these mutations are cytologically visible duplications or deficiencies. They exert their dominant effects through changes in the copy number of wild-type genes and can be divided into two reciprocally acting classes. Class I modifiers are genes that act as enhancers of variegation when duplicated and as suppressors when mutated or deficient. Conversely, class II modifiers are genes that enhance when mutated or deleted and suppress when duplicated. The available data indicate that, in Drosophila, there are 20-30 loci capable of dominantly modifying variegation. Of these, most appear to be of the class I type whereas only two class II modifiers have been identified so far.(ABSTRACT TRUNCATED AT 400 WORDS)
Expression of the CD4 molecule on acute nonlymphocytic leukemia (ANLL) cell lines.
Mature and immature monocytes express the CD4 molecule similar to that expressed on lymphocytes. Since monocytes and cells of myeloid lineage are derived from a common progenitor, we studied a panel of nine myeloid leukemia cell lines for the expression of the CD4 molecule. We found that six of nine myeloid leukemia cell lines (U937, KG1-B, HL-60, THP-1, HEL 92.1.7, KMOE) expressed CD4, the exceptions being the erythroleukemia line K562, myeloblast line KG1-REV, and megakaryocytic line, CHRF-288. SDS-PAGE analysis of HL-60 cells immunoprecipitated with OKT4 showed the presence of a 55 kd molecule similar in weight to that seen on lymphocytes. These data suggest that some myeloid progenitor cells express the CD4 molecule and that the CD4 may have a broader distribution within hematopoietic cells.
Contractile abnormalities of single right ventricular myocytes isolated from rats with right ventricular hypertrophy.
The contractile properties of single rat cardiac myocytes isolated from normal and hypertrophied right ventricles have been investigated and then correlated with the isoenzyme pattern of ventricular myosin. The isoprenaline-stimulated contraction and the beta-adrenoceptor sensitivity were also investigated. Right ventricle hypertrophy was obtained by injecting monocrotaline, an alkaloid which induces severe pulmonary hypertension. The contractile parameters, namely contraction amplitude and speed of shortening, were obtained by means of an inverted microscope TV-system and edge-detection-device. Hypertrophied cells showed a significantly decreased speed of shortening and contraction amplitude when contraction was induced by maximum calcium and maximum isoprenaline. A statistically significant correlation existed between myosin alpha-chain percentage and both contraction parameters. Isoprenaline sensitivity expressed in terms of ED50, p kappa a and Hill coefficient were similar in the control and monocrotaline treated animals. Moreover no correlation between the degree of ventricular hypertrophy and ED50 existed. These results suggest that, in this animal model, the depressed contractile function which characterizes the hypertrophic myocardium depends on changes in isomyosin pattern while beta-adrenoceptor desensitization does not occur.
The c-myc oncogene is regulated independently of differentiation in myeloid cell lines.
Human myeloid leukaemia (U-937 and HL-60) cells when incubated at low cell densities with human recombinant gamma-interferon underwent functional maturation without any loss of proliferative potential relative to uninduced cells. In addition, the proportion of cells in S,G2/M and levels of c-myc oncogene (mRNA and protein) were maintained at the same level as those of untreated control cells. However, cells grown under similar conditions but with retinoic acid matured to the same extent but became growth inhibited with concomitant reductions in the proportion of cells in S,G2/M and levels of c-myc mRNA and protein. These studies indicate firstly that c-myc levels are regulated independently from differentiation in myeloid (non lymphoid) cells, secondly that gamma-interferon can induce differentiation without growth arrest under conditions of low cell density and thirdly emphasise the close association of c-myc expression with proliferative capacity.
Sources of variability for Doppler color flow mapping of regurgitant jets in an animal model of mitral regurgitation.
To determine whether Doppler color flow mapping could be used to quantify changing levels of regurgitant flow and define the technical variables that influence the size of color flow images of regurgitant jets, nine stable hemodynamic states of mitral insufficiency were studied in four open chest sheep with regurgitant orifices of known size. The magnitude of mitral regurgitation was altered by phenylephrine infusion. Several technical variables, including the type of color flow instrument (Irex Aloka 880 versus Toshiba SSH65A), transducer frequency, pulse repetition frequency and gain level, were studied. Significant increases in the color flow area, but not in color jet width measurements, were seen after phenylephrine infusion for each regurgitant orifice. For matched levels of mitral regurgitation, an increase in gain resulted in a 125% increase in color flow area. An increase in the pulse repetition and transducer frequencies resulted in a 36% reduction and a 28% increase in color flow area, respectively. Jet area for matched regurgitant volumes was larger on the Toshiba compared with the Aloka instrument (5.2 +/- 3.1 versus 3.2 +/- 1.2 cm2, p less than 0.05). Color flow imaging of mitral regurgitant jets is dependent on various technical factors and the magnitude of regurgitation. Once these are standardized for a given patient, the measurement of color flow jet area may provide a means of making serial estimates of the severity of mitral insufficiency.
Doppler color flow evaluation of prosthetic mitral valves: experimental epicardial studies.
More than 300 epicardial Doppler color flow mapping studies on 23 different types of clinical and preclinical valves were performed after implantation in the mitral position in sheep. The transducers were placed directly on the heart to obtain the greatest possible resolution. Studies were performed in each animal under different hemodynamic conditions by varying heart rate and cardiac output. Eighty-six valves were studied late (20 to 52 weeks), whereas the remainder were studied early (0 to 10 days) after operation. The valves included 3 types of ball and cage valves, 3 types of disc and cage valves, 7 types of tilting disc valves, 1 type of bileaflet hemidisc mechanical valve, 13 types of porcine aortic valves and 5 types of bovine pericardial valves. The results of these studies were compared with those obtained in 40 studies of 20 native mitral valves. Doppler color velocity/flow profiles were imaged in real time with simultaneous electrocardiographic gating; the aortic flow was also displayed for the timing of velocity/flow events. Native normal mitral valves had no in-orifice flow disturbances and laminar low velocity/flow directed toward the left ventricular apex. Ball and cage and disc and cage valves had high velocity peripheral jets and vortices of velocity/flow reversals distal to the occluders. Tilting disc valves had differing velocity/flow patterns determined by their orientation in the mitral anulus. Bileaflet hemidisc valves had three jets, which decayed 1.5 cm downstream. Porcine aortic and bovine pericardial bioprosthetic valves had high velocity, turbulent, nonaxisymmetric jets (more severe for the latter).(ABSTRACT TRUNCATED AT 250 WORDS)
DNA content in high and intermediate grade non-Hodgkin's lymphoma-prognostic significance and clinicopathological correlations.
Flow cytometric (FCM) estimation of DNA content has been performed on tumour tissue from 197 patients with high and intermediate grade non-Hodgkin's lymphoma (NHL) to investigate the clinicopathological correlations and prognostic significance of DNA ploidy and proliferative activity. Fifty-one per cent of tumours were diploid; the remaining non-diploid tumours were near diploid (14%), aneuploid (28%) and tetraploid (7%). In 81 tumours multiple analyses were performed from different regions of the tumour, ploidy discrepancy was seen within the same tumour in 13/81 tumours (16%), and intra-tumour variation in proliferative index (PI) in 72 tumours was estimated at +/- 5%. Ploidy status did not correlate with histological subtype (Kiel or Rappaport), Ann Arbor stage or the site of disease at presentation. There was no significant difference in response rate, relapse-free survival (RFS) or overall survival rate between the different ploidy categories. Tumour proliferative index (PI) varied markedly between patients (range 2-51%, median 14%). A significant association was observed between PI and histological subtype in the Kiel classification (P = 0.001). The median PI for the lymphoblastic lymphomas was 20% compared with 10% for the centrocytic tumours. An elevated PI was significantly associated with a reduced rate (P = 0.023), with 71% of patients with a low PI (less than 20%) achieving complete remission (CR) compared with 49% patients with a high PI (greater than 20%). Despite this correlation with CR, PI was not significantly associated with overall survival. When the DNA data was combined with over 20 other potential prognostic factors in multivariate analysis, ploidy and proliferative activity did not prove to be of independent prognostic significance for response, RFS or overall survival. In 20 patients additional biopsy material was available from the site of subsequent relapse. In these cases, although the histology at relapse remained unchanged, ploidy status altered in 13/20 patients, and there was a significant rise in tumour PI at relapse compared with the initial pre treatment biopsy (P = 0.017). We conclude that in high and intermediate grade NHL, DNA ploidy as assessed using conventional FCM analysis is not significantly associated with clinical outcome. However, proliferative activity does correlate with histological subtype and response to therapy, and this parameter warrants further evaluation in future studies.
Prognostic factors in high and intermediate grade non-Hodgkin's lymphoma.
An analysis of prognostic factors has been performed on 260 patients with high and intermediate grade non-Hodgkin's lymphoma (NHL) treated over an 11-year period between 1975 and 1986. The overall 5-year survival rate was 50% with a median follow-up of 72 months. Over 20 clinical, radiological and laboratory parameters have been studied, including variables reported to be important indicators of prognosis in previous series, and these variables have been subjected to univariate and multivariate analysis. Attainment of complete remission (CR) was the most important predictor of overall survival, low serum lactate dehydrogenase (LDH), limited stage disease and a high serum albumin were also independently associated with prolonged survival in multivariate analysis. After removing remission status from the model, Ann Arbor clinical stage became the most significant pre-treatment prognostic indicator. Sixty-five per cent of patients achieved CR, and a discriminant analysis showed that failure to attain CR was associated with advanced stage disease, constitutional symptoms, increasing patient age, a low serum albumin and the presence of bulk disease. Advanced clinical stage and an elevated serum LDH predicted independently for a poor relapse-free survival, and reduced overall survival following CR. There was no significant correlation between histological subtype in the Kiel classification and prognosis. This study confirms the prognostic significance of remission status and Ann Arbor clinical stage, and illustrates additional factors including serum levels of albumin and LDH, which serve to enhance the pre-treatment prognostic evaluation of patients with unfavourable histology NHL.
alar4, a constitutive mutant of the A system for amino acid transport, has increased abundance of the Na+,K+-ATPase and mRNA for alpha 1 subunit of this enzyme.
A constitutive mutant, alar4, for the A system of amino acid transport, has increased activity and amount of the A system. This is accompanied by increased sensitivity to ouabain, as measured by efficiency of plating, and increased activity and abundance of the Na+,K+-ATPase that is present in the parental cell line, CHO-K1 (wild type). The latter was shown by increases in (i) ouabain-inhibitable 86Rb uptake in intact cells, (ii) ouabain-inhibitable ATPase activity in mixed membrane vesicles, and (iii) number of ouabain-binding sites and by similar Kd values for ouabain binding and K1/2 for ouabain inhibition of Na+,K+-ATPase as compared to the wild type. The increase in abundance of the Na+ pump is associated with a 4-fold increase in abundance of the mRNA for the alpha 1 subunit of the Na+,K+-ATPase. We could not detect mRNA for alpha 2 or alpha 3 or for the beta subunits. The increase in abundance of the A system and Na+,K+-ATPase is associated with a negligible increase in intracellular Na+ concentration. We propose that the increase in the abundance of the A system and the Na+,K+-ATPase is the result of a mutation in regulatory gene R1 that controls the A system and the Na+,K+-ATPase and is not due to a primary effect of a possible initial increase in Na+ concentration.
Validity of urinary urea nitrogen as a measure of total urinary nitrogen in adult patients requiring parenteral nutrition.
The validity of the urinary urea nitrogen (UUN) estimate of total urinary nitrogen (TUN) was tested in patients who required iv nutrition. UUN and TUN were determined in 120 urine collections from ten preoperative, 13 postoperative, and 11 stressed patients. The relationship between TUN and UUN was examined by linear regression, and analysis of covariance was used on log-transformed data to assess differences between the patient groups. Although there was a close relationship between UUN and TUN for the preoperative patients (r2 = .94, total range of differences = 3.85 g N), this was not as accurate in postoperative and stressed patients (r2 = .69 and .76, respectively, total range of differences = 16.8 and 10.7 g N, respectively). There was no significant difference between the slopes of the regression lines for the relationship between UUN and TUN for three groups (f = 1.1, df = 2114, p less than .3), but the intercepts of the regression lines differed between the preoperative and stressed patient groups (t = 3.47, v = 114, p less than .001). The relationship between TUN and UUN for the whole group was improved by the inclusion of the independent variables of both the patient's clinical state and the urinary creatinine excretion. Arm muscle circumference, which is an estimate of muscle mass, may replace creatinine excretion with little loss in prediction accuracy.
Lack of association between gastric emptying of solids and symptoms in nonulcer dyspepsia.
Gastric motor dysfunction and concomitant gastric stasis have been implicated in the pathogenesis of nonulcer dyspepsia, but a cause-and-effect relationship is not established. Essential dyspepsia refers to a subgroup of nonulcer dyspepsia patients who have no evidence of irritable bowel syndrome, gastroesophageal reflux, or pancreaticobiliary disease. In 32 patients with essential dyspepsia, and 32 randomly selected dyspepsia-free community controls of similar age and sex, we measured gastric emptying of solids using Tc99m-Sulphur Colloid in a fried egg sandwich. Subjects with neuromuscular or other diseases that may alter gastric emptying were excluded. Symptoms were assessed by a standard questionnaire. Data processing was carried out "blinded" to the subjects' clinical status. Female patients took significantly longer to empty half the initial stomach activity (mean 90 min) than female controls (mean, 73 min; p = 0.02). The rate of emptying at 25 min was also significantly less in female patients than in controls. Female and male controls, and male patients, had similar emptying times. Delayed emptying was not associated with the occurrence of postprandial pain, belching, or nausea; there was a trend for the half-time rate of emptying to be greater in patients with abdominal distention. While gastric emptying of solids is slightly delayed in females with essential dyspepsia as a group, this may not explain their symptoms.
Langerhans cells in human lung tumours: an immunohistological study.
In an immunocytochemical study of 41 human lung tumours we have shown that Langerhans cells can be reliably identified using the anti-CD1 monoclonal antibody NA1/34. Langerhans cells are present in all the main varieties of human lung tumour although they are infrequent in both small cell carcinoma and carcinoid tumour. There is considerable variation in numbers of Langerhans cells in both adenocarcinomas and squamous cell carcinomas. In this study tumours were divided into those with high numbers of Langerhans cells (greater than 2 per high power field) and those with low numbers (less than 2 per high power field). Analysing these results against patient survival showed a markedly worse survival in those tumours with a high number of Langerhans cells for all the tumours as a single group and for squamous cell carcinoma as a single entity.
Anticalcification treatments of bioprosthetic heart valves: in vivo studies in sheep.
Studies performed by other investigators have shown that a number of preimplantation processes inhibit the calcification of pieces of porcine aortic valves and of bovine parietal pericardium subcutaneously implanted in rats. To evaluate biological reactivity with these biomaterials functioning in an intracardiac position, mitral and tricuspid valve replacements were performed in young sheep to assess the effects of the following preimplantation processes: (1) surfactants, including sodium dodecyl sulfate, polysorbate-80, Triton X-100 and N-lauryl sarcosine; (2) covalently bound aminohydroxypropane diphosphonic acid; (3) toluidine blue; and (4) incorporation of polyacrylamide into valvular tissues. Quantitative calcium analyses showed that only the surfactants substantially reduced calcification, and only in porcine aortic valvular bioprostheses. However, morphological studies showed that some of these agents also induced alterations that decreased the durability of the valves. Toluidine blue decreased calcification to a degree that was statistically significant, but not biologically important. Polyacrylamide incorporation and diphosphonate binding increased calcification. Thus, data regarding anticalcification treatments obtained from subcutaneous implantation studies in small animal models should be cautiously interpreted and validated by studies with intracardiac valvular implantation in large animals.
Does rheumatoid factor protect lupus patients from the development of nephritis?
It has been suggested again recently that the presence of rheumatoid factor (RF) in the serum of patients with systemic lupus erythematosus (SLE) protects them from the development of nephritis. In this study the RF is measured by standard latex test and by radioimmunoassay to detect IgM, IgA, and IgG isotypes, in patients with SLE with (26 patients) and without (25 patients) renal involvement, and in a control group of 21 patients with idiopathic renal disease. In addition, patients with SLE and nephritis were tested during active and inactive phases of their disease. No significant protective effect was observed from the presence of RF.
Blood doping--a literature review.
There is increasing evidence that the technique of reinfusing an athlete's stored blood prior to competition to improve performance has been used on many occasions. Although early experimental results were controversial and the precise mechanism by which the technique improves performance is still debated, there is now strong evidence that if the blood doping produces a sufficient rise in total red cell mass there are significant improvements in physiological variables such as maximum oxygen uptake, lactate buffering and thermoregulation. These physiological changes are matched by improvements in endurance performance. These may persist in diminishing degree for several weeks, but have to be weighed against the detraining effect produced by the repeated venesection required to obtain an adequate amount of stored blood for autologous reinfusion. Experimental evidence suggests that the transient increase in blood volume and cardiac output following reinfusion is too short lived to be of any real importance and the major effect is related to the increase in total red blood cell mass and haemoglobin enabling an increased transport of oxygen and therefore a potentially greater reserve of blood which can be diverted to non-exercising tissues to improve thermoregulation. The increased red cell mass also improves lactate buffering. Although these benefits have been shown in several studies the increases in performance and measured physiological parameters do not bear a direct relationship to the changes in haematological variables. Blood doping is of considerable importance, not only as an abuse of fair competition, but also because of the light it throws on the physiological limits to endurance performance. It has reawakened controversy as to whether oxygen transport is the limiting factor in endurance.
Aortic valve replacement with combined myocardial revascularisation.
Early and late outcome was studied in 630 patients who underwent aortic valve replacement between 1974 and 1982. Group 1 (506 patients) did not have important coronary artery disease, group 2 (69 patients) had coronary artery disease and underwent coronary artery bypass grafting, and group 3 (55 patients) had coronary artery disease but did not undergo myocardial revascularisation. Early mortality (within 30 days of operation) was significantly lower for group 1 (6%) than for group 2 (13%) and for group 3 (16%). Operative mortality in all three groups was lower in patients operated on more recently. The three year survival of patients in group 1 (83%) was significantly higher than that of patients in group 3 (62%) but not than that of patients in group 2 (76%). The findings of this study suggest that the presence of coronary artery disease increases the risk of aortic valve replacement whether or not coronary artery grafting is performed. Myocardial revascularisation, however, seems to return patients with aortic valve and coronary artery disease to a survival curve similar to that of patients with isolated aortic valve disease.
Automation of APAAP immunocytochemical technique.
A tissue processing instrument (the Histokinette) was modified by the addition of an electronic timing device which allows an immunocytochemical staining technique (the APAAP method) to be performed as a semiautomated procedure. After incubation with primary monoclonal antibodies (applied by hand) slides (up to 72 in a batch) are placed in racks and cycled through tanks of reagents, comprising anti-mouse Ig followed by APAAP complexes with intervening timed draining and washing stages. This semiautomated process gave consistent staining results and offered considerable savings in time compared with conventional methods. The same reagent baths were used over four months on an almost daily basis without deterioration in staining intensity, and consequently the calculated overall cost of the staining procedure was less than if the reagents had been applied by hand and then discarded. The machine is now into its eleventh month of operation; the reagents have been changed twice. It is suggested that this approach, because of savings in time and increased consistency, may be an attractive technique for the routine immunocytochemical staining of slides, and that the nature of the APAAP method is particularly suitable for automation as the necessary reagents can be produced at low cost.