Biomedical subjects

P M Ward

Publications and source records attributed to P M Ward.

At least 19 recordsLinked to original sources

PubMed1999

Endogenous CD8+ T cell expansion during regression of monoclonal EBV-associated posttransplant lymphoproliferative disorder.

There are experimental data which suggest that the primary immune effector cell responsible for maintaining immune surveillance against the outgrowth of EBV-transformed B cells in humans is the CTL, but in vivo proof of this is lacking. In this study we perform a series of cellular and molecular assays to characterize an autologous, endogenous immune response against a transplantation-associated, monoclonal, EBV+ posttransplant lymphoproliferative disorder (PTLD). Following allogeneic bone marrow transplantation, a patient developed a monoclonal PTLD of donor B cell origin. With a decrease in immune suppression, we document the emergence of endogenous, donor-derived CD3+CD8+ CTLs, followed by regression of the PTLD. The TCR Vbeta repertoire went from a polyclonal pattern prior to the development of PTLD to a restricted TCR Vbeta pattern during the outgrowth and regression of PTLD. Donor-derived CD3+CD8+ T lymphocytes displayed MHC class I-restricted cytolytic activity against the autologous EBV+ B cells ex vivo without additional in vitro sensitization. The striking temporal relationship between the endogenous expansion of a TCR Vbeta-restricted, CD3+CD8+ population of MHC class I-restricted CTL, and the regression of an autologous monoclonal PTLD, provides direct evidence in humans that endogenous CD3+CD8+ CTLs can be responsible for effective immune surveillance against malignant transformation of EBV+ B cells.

Adult↗

PubMed1996

Clonal evolution in B-lineage acute lymphoblastic leukemia by contemporaneous VH-VH gene replacements and VH-DJH gene rearrangements.

B-cell acute lymphoblastic leukemia (B-ALL), more frequently than any other B-lineage neoplasm, exhibits oligoclonal Ig heavy chain (IgH) gene rearrangement in 15% to 43% of all cases studied. To study the molecular processes that promote multiple IgH rearrangements, a comprehensive sequence analysis of a B-ALL case was performed in which seven clonal IgH gene rearrangements were identified. The genetic profiles suggested that a single leukemic progenitor clone evolved into several subclones through dual processes of variable (VH) to preexisting diversity-joining (DJH) gene segment rearrangement and VH to VH gene replacement. Predominant IgH-V usage and the uniquely rearranged clonotype-specific VHDJH region gene sequences were identified using a novel DNA-based gene amplification strategy. Polymerase chain reaction (PCR) was directed by an IgH-J generic primer and a complement of family-specific IgH-V primers that defined the major B-cell IgH-V gene usage. Clonality of rearranged VHDJH bands was substantiated by high resolution denaturant gel electrophoretic analysis. Sequence patterns of the amplified VHDJH fragments segregated into two groups defined by common DJH sequences. Partial N region homology at the VHD junction as well as shared DJH sequences firmly established VH to VHDJH gene replacement as a mechanism generating clonal evolution in one group. In the second subset, oligoclonality was propagated by independent VH gene rearrangements to a common DJH precursor. The contributions of all clonal Ig-VHDJH repertoires for each group was approximately 50% and reflected a symmetric distribution of leukemic subclones generated by either process. Thus, oligoclonal rearrangements evolved by two independent, yet seemingly contemporaneous molecular genetic mechanisms. All seven clones displayed nonfunctional Ig-VHDJH recombinations. These observations may have relevance to the recombinatorial opportunities available during normal B-cell maturation.

Base Sequence↗

PubMed1996

Sevoflurane degradation by soda lime in a circle breathing system.

Sevoflurane is degraded by soda lime to a vinyl ether commonly referred to as compound A. We measured the concentration of compound A in the circle breathing system of 31 patients receiving sevoflurane anaesthesia. Inspiratory and expiratory gas samples were analysed using gas chromatography and flame ionisation detection. The end-tidal sevoflurane concentration and soda lime temperature were recorded. The peak compound A concentration ranged between 10 to 32 ppm in the inspiratory limb and 7 to 26 ppm in the expiratory limb. There was a positive correlation between the peak compound A concentration and the end-tidal sevoflurane concentration (r2 = 0.545, p < 0.0001) and the soda lime temperature (r2 = 0.301, p = 0.0014). We conclude that the end-tidal concentration of sevoflurane and the temperature of the soda lime are important variables in determining concentration of compound A in a circle system.

Adult↗

PubMed1995

Profile of immunoglobulin heavy chain variable gene repertoires and highly selective detection of malignant clonotypes in acute lymphoblastic leukemia.

The predominant B cell immunoglobulin heavy chain variable gene (IgH-V) usage and the uniquely rearranged, clonotype-specific variable-diversity-joining region gene (VDJ) sequences were identified in patients with B cell acute lymphoblastic leukemia (B-ALL) using a novel DNA-based gene amplification strategy. The approach allows a thorough and sensitive determination of the number of clonal leukemic IgH rearrangements and their precise V gene usage. This strategy may be applied in the detection of minimal residual disease, in surveillance after induction of disease-free states, and in analyzing the effectiveness of purging autologous bone marrow of malignant clones. An initial primary polymerase chain reaction (PCR), directed by an IgH-J generic primer and a complement of family-specific IgH-V primers, defined the major B cell IgH-V gene usage. Use of an IgH-J generic primer supplanted the use of a constant region primer anchor and thus eliminated the need to target mRNA by the traditional RNA reverse transcription-PCR amplification method. Monoclonality of rearranged VDJ bands was further substantiated by high-resolution denaturant gel electrophoretic analysis. The predominant amplified bands were subcloned and sequenced. By sequencing through VDJ juxtaposed regions, that is, the third complementarity-determining region, clonotype-specific primers were developed and used in a secondary clonotype primer-directed PCR (CPD-PCR) to detect, with extreme sensitivity and specificity, a unique B cell clone. Analysis of the products of the CPD-PCR permitted the detection of a single malignant cell among 1 million polyclonal cells and superseded the constraints of prior studies that have provided a limited evaluation of family variable gene repertoire usage. Leukemic clonal rearrangements were detected in 100% of the eight cases of pediatric and two cases of adult B-ALL studied. Two or more clonal IgH-VDJ amplified sequences were observed in 50% of the B-ALL bone marrows analyzed. In two cases, clonotype-specific oligodeoxynucleotide primers, derived from B-ALL VDJ sequences, directed the secondary CPD-PCR, and disease activity was monitored after chemotherapy and allogeneic bone marrow transplantation.

Adult↗

PubMed1995

Is there a need for a new inhalational anaesthetic agent?

New anaesthetic agents are continually being developed in an effort to prepare the ideal agent. Isoflurane is the first choice of many anaesthetists, although it clearly falls short of the ideal on a number of counts. The need and place for any new agent depends on comparing the properties of a theoretically ideal agent with those of isoflurane and the new agent. Desflurane is a step towards a more ideal inhaled agent; however, there is still the need to synthesise and evaluate new chemical entities in order that the ideal can more nearly be approached.

Anesthesia, Inhalation↗

PubMed1993

The management of tracheal rupture using bilateral bronchial intubation.

The management of a patient who required positive pressure ventilation following pharyngolaryngo-oesophagectomy during which tracheal injury was sustained is described. Ventilation with a tracheal tube resulted in a massive pneumoperitoneum. Bilateral bronchial intubation was employed with success.

Bronchi↗

PubMed1993

The Latin American inner city: differences of degree or of kind?

Inner-city areas of Latin America are examined and compared with similar urban areas in the United Kingdom and the United States. Significant differences are noted in that "the demography [of Latin American inner cities] is different, with relatively low levels of visible population decline; and the economy of the inner city remains vibrant, focusing upon services and small-scale artisan activities, with no corresponding decline in heavy industry. Although large-scale redevelopment projects in and around the downtown were common during the 1940s to the 1960s, the demise of authoritarian and dirigiste-type leaders, 1980s austerity, and a growing democratic base, have imposed severe limitations on the extent of large-scale urban redevelopment and reinvestment."

Demography↗

PubMed1993

Chemotherapy induced nausea and emesis in pediatric cancer patients: external validity of child and parent emesis ratings.

Children's and parent's subjective ratings of the frequency and severity of nausea and emesis were assessed among 33 children with acute lymphoblastic leukemia receiving identical chemotherapy. Parents were trained to record the frequency of the child's actual emesis episodes during chemotherapy. Although parent and child ratings of nausea were significantly correlated, children generally rated their nausea and emesis as more frequent and more severe than did their parents. Parent ratings showed inadequate external validity when compared with behavioral observations. Children with greater anxiety and higher subjective ratings subsequently exhibited more frequent episodes of emesis by observation, suggesting that their perceptions of symptoms based on previous chemotherapy experiences may predict emesis during different chemotherapy. In a stepwise multiple regression analysis, antiemetic regimen and the child's anxiety as rated by the parent combined to account for approximately 47% of the variance in number of episodes of emesis. These findings are discussed in the context of factors limiting validity of parent and child reports of children's symptomatology with implications for future epidemiologic and intervention research.

Adolescent↗

PubMed1991

Midazolam premedication for pediatric bone marrow aspiration and lumbar puncture.

The ability of midazolam, a benzodiazepine, to reduce the distress associated with lumbar puncture and bone marrow aspiration was examined in 23 children with acute lymphocytic leukemia. Patients were randomized to receive 0.2 mg/kg midazolam HCl or placebo intravenously 3-5 min before the procedures, under double-blind conditions. Based on prior experiences, children in both groups anticipated severe pain from these procedures. Postprocedure pain ratings by patients were markedly reduced in the midazolam but not the placebo group. Both physicians and parents judged the midazolam group as significantly less distressed than controls during and after the procedures. Trained observers recorded significantly fewer pain- and anxiety-related behaviors in the midazolam group immediately before and after, but not during the procedures. The amnestic effects of midazolam, confirmed in a visual recall/recognition test, appear to account for the decreased pain ratings since the behavioral manifestations were similar in the two groups. There were no adverse drug reactions or significant changes in vital signs. Midazolam warrants further investigation as a premedication for painful diagnostic and treatment procedures in children with cancer.

Adolescent↗

PubMed1990

Contributions of vascularized lymph-node metastases to hematogenous metastasis in a rat mammary carcinoma.

Rats received hind-foot-web (FWI) injections of MT-100-TC mammary carcinoma cells; the resultant tumor metastasized first to the popliteal lymph nodes. Over the course of 4 weeks, in association with increases in tumor weight, the blood-flow to the popliteal nodes increased 18-fold, and their vascular densities increased 2-fold. In spite of this vascularization, cancer cells were detected in only 3 of 648 blood vessels associated with involved, ipsilateral lymph nodes compared with intravascular cells in 82 of 314 vessels associated with "primary" foot-pad lesions. The presence of tumorigenic cancer cells in the right ventricular blood of animals bearing these tumors is, therefore, considered to result from their direct entry into blood vessels from the "primary" lesions, and/or from extra-nodal invasion of vessels in tissues to which nodal tumors were adherent, as distinct from passage via lymphatico-venous communications between tumors and nodal blood-vessels. The reconstructed events occurring in the rat model, with effective restriction of regional node metastases to the nodes themselves for a time, could possibly account for the long-term survival of some patients with breast cancer and regional-node metastases, following surgery.

Animals↗

PubMed1989

Effects of disseminative route on the liver- and lung-colonizing efficiencies of B16 melanoma and colon-26 carcinoma in mice.

Tumor-colony formation in the liver and lungs of mice was assessed, after delivery of equal numbers of B16 melanoma or colon-26 carcinoma cells via the portal vein or the hepatic artery, and via the pulmonary artery or the bronchial artery. Significantly greater lung involvement occurred after delivery of both cell types via the bronchial artery than via the pulmonary artery. In the case of colon-26 cells, liver colonization via the hepatic artery was more efficient than via the portal vein. In the case of B16 cells, no route-dependent differences in liver colonization were detected. Our results indicate that during hematogenous metastasis, the vascular route taken by some cancer cells to the same target organ may considerably modify the efficiency with which they form metastases.

Animals↗

PubMed1989

Metachronous seeding of lymph node metastases in rats bearing the MT-100-TC mammary carcinoma: the effect of elective lymph node dissection.

Following the introduction of cancer cells into the lymphatic system, metastases in 'down-stream' lymph nodes often appear in a sequential manner. This could be due to synchronous seeding of the in-line nodes with progressively diminishing numbers of tumorigenic cancer cells, or alternatively, by discrete, stepwise (metachronous) seeding of 'down-stream' nodes by 'up-stream' nodal metastases acting as 'generalizing' sites. Metachronous seeding to local lymph nodes is potentially curable by elective lymph node dissection; synchronous seeding is not. Synchronous versus metachronous seeding of lymph node metastases was investigated using the MT-100-TC mammary carcinoma injected into the hind foot-webs of rats. When the primary tumor was removed by amputation one week after injection, 1/15 animals survived; in contrast, removal of the draining popliteal lymph node in addition to the primary lesion, resulted in 8/19 long-term survivors. At this time, occult metastases detectable by bioassay but not by conventional histology, were present in all draining popliteal nodes and in 60 percent of lungs. The fact that some amputees were cured when the popliteal node was removed, indicated the metachronous nature of nodal metastases in this system. Further, recurrence of nodal and lung metastases in those amputees in which the popliteal node was left intact, identified the popliteal node as a 'generalizing' site. By the time popliteal node involvement was evident by conventional histology, micrometastases were present in 'down-stream' nodes, and accordingly, removal of the popliteal node and the primary lesion at this time was not curative.

Amputation, Surgical↗

PubMed1989

Violent death in the pediatric age group: rural and urban differences.

Violent death (homicide and suicide) in the pediatric age group is a major public health problem. A descriptive study was undertaken to review retrospectively the 1077 pediatric coroner's cases in 11 California counties for differences between urban and rural violent death rates. Pediatric violent death was more prevalent in the urban region than in the rural region (P less than 0.0007). High urban homicide rates accounted for most of this difference. Suicide rates were not significantly different (P = 0.18). Seventy-four percent of the violent deaths were in the 15- to 18-year age group, and most of these deaths were caused by firearms (81%). Blacks had the highest homicide and suicide rates. Child abuse was an important cause of death for young children in the urban area only. Socioeconomic factors, cultural differences, high population density, and the availability of firearms were proposed as factors affecting violent death in the pediatric age group.

Adolescent↗

PubMed1989

Pediatric deaths and emergency medical services (EMS) in urban and rural areas.

A total of 1078 pediatric coroners' cases in 11 rural and urban California counties were reviewed as they relate to emergency medical services (EMS). Pediatric coroners' death rates per 100,000 population varied from an average of 2.17 in the rural region to 30.4 in the urban region. Vehicular accidents caused the majority (66%) of the accidental deaths, and firearms caused 61% of the violent deaths. Violent deaths (homicide and suicide) were significantly more common in the urban region (P less than 0.001), and vehicular deaths (excluding auto versus pedestrian) were more common in the rural region (P less than 0.001). EMS provider usage was greater in the urban areas (84 vs 66%, P less than 0.001), as was the number of cases receiving advanced life support (97 vs 66%, P less than 0.001). Urban and rural differences in place of death were significant for two places of death; street and highway, and inhospital deaths. A significantly greater number of children died on the street/highway in rural areas (P less than 0.05). Hospital deaths were more likely to occur on the ward in the rural region, versus the intensive care unit in the urban region (P less than 0.001). Proposed factors which may explain these findings include differences in medical resources and in local transfer policies. The study demonstrates that EMS providers are involved in the care of children who have had a fatal emergency. Further evaluation of rural and urban differences in prehospital care of the pediatric patient is indicated.

Adolescent↗

PubMed1988

Effects of metastatic cascades on metastatic patterns: studies on colon-26 carcinomas in mice.

The present studies are based on autopsy data showing that in upper esophageal and lower rectal carcinomas, hematogenous metastasis occurs mainly first to the lungs, and cancer cells from pulmonary metastases generate arterial metastases. In lower esophageal and upper rectal carcinomas, hematogenous metastases occur first in the liver, then in the lungs, and are further disseminated by the arterial route. The arterial metastatic patterns are different in the 2 groups. One possible explanation for these differences in pattern is that liver "residence" is associated with different metastatic behavior; this has been tested in a model system. Experiments with the transplantable colon-26 carcinoma in mice reveal that, when cancer cells from common s.c. transplant sites are grown in the liver, lungs or liver-and-lungs, and then injected into the bloodstream of fresh recipients via the left ventricle, the portal vein or the tail vein, different patterns and degrees of colonization of 11 different target sites are observed. These results are consistent with the hypothesis that growth of cancers in different anatomic sites may modify the subsequent arterial metastatic patterns, due to site-induced changes occurring in cancer cell populations, which influence metastasis from metastases or so-called "cascade" processes.

Animals↗

PubMed1987

Lymphogenous and hematogenous metastasis of Lewis lung carcinoma in the mouse.

Quantitative and temporal comparisons were made between lymphogenous and hematogenous metastasis in the non-immunogenic model system of mice bearing transplanted 3LL tumors in their hind feet. The experimental evidence indicates that cancer cells disseminate from clinically detectable primary cancers by non-exclusive routes in the blood-stream and in the lymphatics. Following a delay of approximately 2 weeks after injection of 3LL cancer cells into the foot, local lymph-node micrometastases occur, together with the first appearance of overt hematogenous metastases in the lungs. The anatomic extent of lymph-node involvement, determined by bioassays of orthotopic grafts, of ipsilateral popliteal, inguinal and lumbar nodes, provides an accurate indicator of hematogenous metastasis, even though lymphogenous and hematogenous metastasis are operationally independent in this tumor/host system.

Animals↗

PubMed1986

The stability of kidney-induced selection of Lewis lung tumor cell populations, and their metastasis-related behavior.

The surface charge densities of Lewis lung carcinoma (3LL) cells were measured in tumors transplanted into subcutaneous (s.c.) sites, and into the kidneys (K), as well as in kidney tumors transplanted to, and maintained in, the s.c. site (K.s.c.). K cells showed a significant increase in net negativity in comparison with s.c. cells, which was stable over II passages. On back-transplantation of K cells to the s.c. site, the net negativity of K.s.c. cells was higher than that of the s.c. cells, but the increase was stable for only 7 passages; on subsequent passages the net negativity fell, approaching that of the s.c. cells. Detailed analyses suggest the presence in these tumors of 2 subpopulations of 3LL cells, whose proportions change in the different sites studied to produce changes in the mean electrophoretic mobilities of the whole cancer cell populations. The altered proportions of the 2 cell types in the 3 sites were not associated with major changes either in their general behavior with respect to metastasis, or in differential growth in various organs following s.c., tail vein, and left ventricular injections. Selection induced by growth in the kidney, as evidenced by physiochemical changes at the cancer cell surface, was not associated with kidney preference in metastasis or metastasis-related behavior.

Animals↗

PubMed1985

The effects of single versus triple intravenous injections of B16 melanoma cells on the development of pulmonary tumors in mice.

During natural metastasis, cancer cells are released continuously into the bloodstream and arrested in target organs; the process is repetitive rather than a single event. In this communication, the effect of preceding on successive "pulses" of cancer cells is discussed in relation to the arrest, retention and tumor formation of B16 melanoma cells in the lungs of mice receiving 3 separate tail-vein injections at 2-hr intervals. When animals received the same total number of cells in either 1 or 3 injections, no significant differences were detected in the initial arrest and subsequent retention in the lungs. However, 15 days after injection, mice which had received 3 pulses of cancer cells were found to have fewer pulmonary tumors than those which had received a single pulse of cells. The results show that interactions between 2 successive waves of B16 melanoma cells and their host did not affect the initial arrest and "short-term" retention of a third wave of radiolabelled cells. However, the "longer-term" experiments on tumor formation show that preceding pulses of cancer cells resulted in the lungs becoming more hostile to a succeeding pulse than was the case in appropriate controls. The results indicate that the relative metastatic capacities of cancer cells arrested in microvascular beds during hematogenous metastasis could well be diminished by antecedent interactions of this type.

Animals↗