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Biomedical subjects

D Amos

Publications and source records attributed to D Amos.

At least 19 recordsLinked to original sources
PubMed2000

Physiological and cognitive performance of soldiers conducting routine patrol and reconnaissance operations in the tropics.

The physiological and cognitive performance of acclimatized soldiers undertaking routine patrol and reconnaissance activities in the tropics was investigated. Data were obtained during a patrol and a reconnaissance exercise followed by a short assault. Ambient conditions were characterized by temperatures of 30 to 33 degrees C, low humidity (52-59%), and moderate to high solar radiation. Maximum metabolic rates during patrol were high, although the equipment carried was modest and the terrain was not severe. Rectal temperatures peaked at 38.2 and 38.4 degrees C for patrol and assault activities, respectively; peak heart rates were 160 beats min-1 for each activity. Sweat rates of approximately 9 and 14 g kg-1 body weight h-1 were recorded for patrol and assault activities, respectively. The soldiers maintained adequate hydration levels and displayed no evidence of deterioration in cognitive performance. The data show that routine operational activities in tropical conditions induced physiological strain in acclimatized soldiers. However, this strain was not maintained at hazardous levels for lengthy periods.

Acclimatization↗
PubMed1997

"Growing pains": clinical and behavioral correlates in a community sample.

Parents of 183 children identified them as having "pain in arms, legs, or joints during the previous 12 months." This group was compared with a group of children without pains selected randomly from the rest of a 1605-member community-based cohort in a study of chronic illness. The pains were most likely to be deep seated, to involve predominantly the lower limbs, and to be described in vague, nonspecific terms. These children were significantly more likely to have recurrent abdominal pain, a negative mood, and behavior problems, and to be aggressive, anxious, and hyperactive. There were no differences between the groups on any teacher ratings of behavior, temperament, social skills, or academic achievement. We conclude that children with "growing pains" are rated by their parents, but not their teachers, as having different temperamental and behavioral profiles than controls. These data suggest a psychosocial contribution to growing pains akin to that seen with other pain syndromes.

Adolescent↗
PubMed1997

The physiological strain induced by a new low burden chemical protective ensemble.

The physiological responses of a group of nine subjects exercising at a metabolic rate of 510 W in a new low burden chemical protective ensemble, the Chemical/Biological Combat Suit (CBCS), have been determined under a warm, humid climatic condition, 30 degrees C and 60% relative humidity. The CBCS was significantly superior to a current NBC overgarment (MK4) in terms of induced physiological strain. Furthermore, there was no statistically significant difference between the normal combat uniform (DPCU) and the CBCS worn as a combat uniform (CS), without hood, mask and gloves, in terms of increase in rectal temperature and increase in heart rate. The major limitation on performance in the fully encapsulated CBCS was imposed by the combination of mask, permeable hood and impermeable gloves. It was concluded that there would be a significant improvement in soldier performance in the CBCS rather than in the current MK4 overgarment and that there would be no detriment to soldier performance when wearing the CS uniform in times of chemical threat.

Adult↗
PubMed1996

Infrared tympanic temperature as a predictor of rectal temperature in warm and hot conditions.

BACKGROUND: Infrared (IR) thermometry has been proposed as a rapid, non-invasive means of monitoring core temperature. However, it has not been validated for use in warm to hot environments. HYPOTHESIS: IR tympanic temperature (Tty) accurately predicts rectal temperature (Tre) during simulated marching in warm and hot conditions. METHODS: Tty, and thermistor-derived Tre, aural canal (Tac) and cheek skin (T cheek) temperatures were monitored in seven males during 100 min of treadmill walking, in combat uniforms, at 5 km.h-1, slope 6%, in warm (30 degrees C, 60% RH) and hot (40 degrees C, 30% RH) conditions. RESULTS: Tty was significantly different to Tre in hot, but not warm, conditions. Final Tty was 0.2 degrees C < Tre in warm, but 0.4 degrees C > Tre in hot, conditions. From 60-100 min of the warm trial, Tty predicted Tre with a standard error of estimate (SEE) of 0.15 degrees C (r = 0.9, p < 0.0001). In a multiple regression model, the combination of Tty, Tac, and Tcheek reduced this SEE to 0.1 degrees C. In the H trial, from 60-100 min Tty predicted Tre with a SEE of 0.21 degrees C (r = 0.7, p < 0.0001). Tty and Tac correlated significantly in both trials. CONCLUSIONS: (1) the IR method should provide useful estimates of Tre in the field provided the influence of ambient conditions is taken into account; (2) the IR method is not as reliable as rectal monitoring in distinguishing accurately between degrees of heat strain; and (3) Tre prediction with the IR device may be improved in warm conditions if skin temperatures are combined with Tty.

Adult↗
PubMed1992

Mixed leukocyte culture reactivity and graft-versus-host disease in HLA-identical marrow transplantation for leukemia.

The results of pretransplant mixed leukocyte culture (MLC) assays were compared to subsequent risk of graft-versus-host disease (GVHD) in 783 patients receiving marrow transplants from HLA genotypically identical sibling donors. The mean MLC response observed between 1303 normal HLA identical sibling pairs was 0.0 +/- 4.2% RR. The donor anti-recipient MLC reaction, an in vitro response that presumably might be relevant to GVHD, was significantly increased (greater than mean + 2 sd) in 83 (10.6%) of the cases, most often in patients in relapse at the time of testing. No association was found, however, between this increased donor anti-recipient MLC reactivity pretransplant and the incidence or severity of subsequent acute or chronic GVHD. These data suggest that the increased MLC responses sometimes observed between leukemia patients and their HLA identical sibling donors prior to marrow transplantation do not represent genetic differences capable of causing GVHD.

Bone Marrow Transplantation↗
PubMed1991

Transfusions shortly before HLA-matched marrow transplantation for leukemia are associated with a decrease in chronic graft-versus-host disease.

The effect of random red cell transfusions given shortly before allogeneic bone marrow transplantation (BMT) was evaluated in 969 leukemic patients transplanted from an HLA-identical sibling donor. Patients were divided into two groups: 501 who received a transfusion shortly before BMT, and 468 who did not. Both groups had a similar incidence of acute graft-versus-host disease (GVHD), but the recently-transfused group had a significantly lower incidence of chronic GVHD (35.9% vs 48.9%). These differences remained significant in a multivariate analysis of time to chronic GVHD (p = 0.022), taking into account other differences between the two groups and known risk factors for chronic GVHD.

Adult↗
PubMed1990

Comparison of interleukin 2 and gamma-interferon production by peripheral blood mononuclear cells in response to cytomegalovirus after marrow transplantation.

Forty-five patients were prospectively studied during the first 100 days after allogeneic marrow transplant to determine the relationship between cytomegalovirus-specific gamma-interferon and interleukin 2 production by peripheral blood mononuclear cells and CMV infection. IL-2 production was significantly lower than normal throughout the study period (P = 0.0001). In contrast, mitogen-induced gamma-interferon production was in the normal range by days 41-60 while CMV antigen induced gamma-interferon production by PBMC was normal by 81-100 days after transplant. Antibody- and complement-depletion studies showed that T4 helper cells were capable of gamma-interferon production in response to CMV antigen despite deficient IL-2 production. Neither gamma-interferon nor IL-2 production distinguished CMV-infected from uninfected patients. However, CMV-infected patients had significantly more T8 cytotoxic/suppressor cells than did uninfected patients by 81-100 days after transplant (P = 0.001). In vitro addition of IL-2 significantly increased gamma-interferon production by PBMC from patients with reduced production, suggesting that decreased gamma-interferon production may be related to deficient IL-2 production. Deficiencies in both CMV-specific IL-2 and gamma-interferon production may contribute to the high frequency and severity of CMV infection after marrow transplantation.

Adolescent↗
PubMed1990

Psychiatric illness and irritable bowel syndrome: a comparison with inflammatory bowel disease.

Structured psychiatric interviews and psychological self-report measures were administered to 28 patients with irritable bowel syndrome and 19 patients with inflammatory bowel disease. Significantly more of the patients with irritable bowel syndrome had lifetime diagnoses of major depression, somatization disorder, generalized anxiety disorder, panic disorder, and phobic disorder. They had significantly more medically unexplained somatic symptoms, and most had suffered from psychiatric disorders, particularly anxiety disorders, before the onset of their irritable bowel symptoms.

Adult↗
PubMed1989

Effect of HLA compatibility on engraftment of bone marrow transplants in patients with leukemia or lymphoma.

We analyzed the relevance of HLA compatibility to sustained marrow engraftment in 269 patients with hematologic neoplasms who underwent bone marrow transplantations. Each patient received marrow from a family member who shared one HLA haplotype with the patient but differed to a variable degree for the HLA-A, B, and D antigens of the haplotype not shared. These 269 patients were compared with 930 patients who received marrow from siblings with identical HLA genotypes. All patients were treated with cyclophosphamide and total-body irradiation followed by the infusion of unmodified donor marrow cells. The rate of graft failure was 12.3 percent among the recipients of marrow from a donor with only one identical haplotype, as compared with 2.0 percent among recipients of marrow from a sibling with the same HLA genotype (both haplotypes inherited from the same parents) (P less than 0.0001). The incidence of graft failure correlated with the degree of donor HLA incompatibility. Graft failure occurred in 3 of 43 transplants (7 percent) from donors who were phenotypically HLA-matched with their recipient (haplotypes similar, but not inherited from the same parents), in 11 of 121 donors (9 percent) incompatible for one HLA locus, in 18 of 86 (21 percent) incompatible for two loci, and in 1 of 19 (5 percent) incompatible for three loci (P = 0.028). In a multivariate binary logistic regression analysis, independent risk factors associated with graft failure were donor incompatibility for HLA-B and D (relative risk = 2.1; 95 percent confidence interval, 1.7 to 2.5; P = 0.0004) and a positive crossmatch for anti-donor lymphocytotoxic antibody (relative risk = 2.3; 95 percent confidence interval, 1.8 to 2.8; P = 0.0038). Residual host lymphocytes were detected in 11 of 14 patients with graft failure, suggesting that the mechanism for graft failure could be host-mediated immune rejection. We conclude that donor HLA incompatibility and prior alloimmunization are significant risk factors for graft failure, and that a more effective immunosuppressive regimen than those currently used is needed for consistent achievement of sustained engraftment of marrow transplanted from donors who are not HLA-identical siblings.

Adolescent↗
PubMed1989

Effect of delay in processing on lysis-centrifugation blood culture results from marrow transplant patients.

The effect of delay in processing on results of lysis-centrifugation (LC; Isolator) blood cultures was assessed in 4,577 paired blood specimens. Blood specimens were obtained at all hours from 384 febrile marrow transplant patients with indwelling venous catheters and were processed by the LC technique and by a conventional two-bottle method. Most patients (84%) were receiving broad-spectrum antibiotics at the time of blood culture. Specimens were delivered to the laboratory, where Isolator tubes were held at 35 degrees C and processed in batches between 0700 and 1730 h daily. This procedure resulted in a delay beyond the manufacturer-suggested processing time of less than 8 h for 1,853 (42%) of the LC cultures. There was no overall difference in the recovery of organisms present in LC cultures processed after being held for 8 to 24 h compared with the conventional two-bottle method. LC methodology had shorter time to detection than the conventional method for detection of Candida spp. and Pseudomonas spp. (P less than 0.05). However, time to detection for Streptococcus spp. and members of the family Enterobacteriaceae, responsible for 16.3% of total isolates, was prolonged significantly by delay in processing when compared with the conventional two-bottle method (P less than 0.01). Results of this study support the recommendation of the manufacturer for processing of Isolator tubes within 8 h or less. Although one can safely delay processing beyond 8 h in terms of total recovery of organisms, such delays were associated with longer time to detection for certain important potentially pathogenic organisms which accounted for a sizeable proportion of blood culture isolates from marrow transplant patients.

Anti-Bacterial Agents↗
PubMed1989

Analysis of prognostic factors for the outcome of marrow transplantation or further chemotherapy for patients with acute nonlymphocytic leukemia in first remission.

To test whether variables at diagnosis can identify patients with acute nonlymphoblastic leukemia (ANL) for whom bone marrow transplantation (BMT) is more likely to be of benefit and those for whom continued chemotherapy is a better approach, the association of 15 clinical and laboratory factors with outcome was investigated among 220 patients (ages 1 to 53 years) treated with cyclophosphamide and total body irradiation (TBI) followed by allogeneic BMT, and among 392 patients (ages 13 to 50) administered intensive chemotherapy. In the BMT group, female sex, younger age, the absence of hepatitis during induction, a larger percentage of circulating blasts, and a shorter duration of symptoms were associated with longer survival, whereas only female sex and younger age favorably influenced disease-free survival (DFS). In the chemotherapy group, younger age, lower WBC at diagnosis, a single successful induction course, and the absence of circulating promyelocytes were associated with longer survival, whereas only a lower WBC and a lower percentage of peripheral neutrophils were associated with longer DFS. Estimated regression coefficients for treatment-by-prognostic-factor interactions were used to characterize subgroups of patients in which one treatment or the other produced better outcomes. BMT and chemotherapy produced similar durations of survival in a subset of patients characterized by many or all of the following: older age, male sex, achievement of complete remission (CR) after one induction, and absence of circulating blast cells at presentation. These data suggest that, using pretreatment variables, subgroups of patients can be identified for whom either BMT or continued chemotherapy is most likely to be beneficial.

Adolescent↗
PubMed1989

Engraftment in 86 with patients lymphoid malignancy after autologous marrow transplantation.

The kinetics of marrow engraftment was retrospectively analysed in 55 patients with malignant lymphoma (ML) and 31 patients with acute lymphoblastic leukemia (ALL) after marrow-ablative therapy followed by autologous bone marrow transplantation. Thirty-eight percent of patients with ML, most of whom were transplanted in relapse and 13% of patients with ALL, mostly transplanted in remission, showed failed or delayed engraftment. Analysis of the total patient group showed that failure to recover platelet counts was significantly correlated with detection of disease in the marrow early after transplantation (p less than 0.001). Platelet recovery was also correlated with survival (p = 0.0001), disease-free survival (p = 0.0001), and the probability of relapse (p = 0.02). In those patients achieving engraftment, multivariate regression analysis failed to reveal any single in vitro test of marrow nucleated cell or progenitor cell numbers that significantly influenced time to achieve recovery of either granulocyte or platelet counts.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Ovarian function following marrow transplantation for aplastic anemia or leukemia.

One hundred eighty-seven women between 13 and 49 years of age had ovarian function evaluated from 1 to 15 years (median, 4) after marrow transplant for aplastic anemia or leukemia. Among 43 women transplanted for aplastic anemia following 200 mg/kg cyclophosphamide (CY), all 27 less than 26 years of age, but only five of 16 greater than 26 years of age recovered normal ovarian function. Nine of the 43 have had 12 pregnancies, resulting in eight live births, and two elective and two spontaneous abortions. All eight children are normal. Nine of 144 women transplanted for leukemia following 120 mg/kg CY and 9.20 to 15.75 Gy total body irradiation (TBI) recovered ovarian function. Two of these nine have had three pregnancies, resulting in two spontaneous and one elective abortion. The probability of having ovarian failure was 0.35 by 7 years for patients receiving CY alone and was 1.00 at 1 year for patients receiving CY plus TBI (P less than .0001). By 7 years after transplant the probabilities of having normal ovarian function were 0.92 after CY alone and 0.24 after CY plus TBI (P less than .0001). Multivariate analysis showed that TBI was the only factor significantly influencing ovarian failure and that both TBI and greater patient age at transplant were significantly associated with a decreased probability of recovering normal ovarian function. These data demonstrate that after high-dose CY, recovery of ovarian function occurs in younger women and in a minority of older women, but after CY and TBI, recovery occurs in only a few younger women and none of the older women.

Adolescent↗
PubMed1987

Evaluation of intensive postremission chemotherapy for adults with acute nonlymphocytic leukemia using high-dose cytosine arabinoside with L-asparaginase and amsacrine with etoposide.

In order to test the toxicity and efficacy of intensive postremission therapy with high-dose cytosine arabinoside with L-asparaginase and amsacrine with etoposide in adults with acute nonlymphocytic leukemia (ANL), 100 adults (ages 19 to 75) with previously untreated ANL were entered into a study using six sequential cycles of chemotherapy. Cycles 1 (induction), 3, and 5 included conventional doses of daunomycin, cytosine arabinoside, 6-thioguanine, vincristine (VCR), and prednisone. Cycle 2 was cytosine arabinoside 3 g/m2 intravenously (IV) every 12 hours for four doses, followed by L-asparaginase 10,000 U intramuscularly (IM) at hour 42; this combination was repeated 1 week later. Cycle 4 included amsacrine 120 mg/m2/d and etoposide 100 mg/m2/d, both IV for five days, and cycle 6 was three monthly courses of VCR on day 1, and prednisone, mercaptopurine, and methotrexate each for five days. Seventy-four patients (74%) achieved complete remission (CR) (51 with cycle 1 and 23 after cycle 2). The overall disease-free survival (DFS) for patients achieving CR is 27% at 3 years by Kaplan-Meier analysis, while for patients achieving CR with cycle 1 it is 34%. The actuarial probability of being free from relapse at 3 years for patients achieving CR is 34%. Sixteen of the 74 CR patients (22%) died in CR while continuing to receive intensive chemotherapy, including 12 (18%) who succumbed to infection (nine bacterial, three fungal). After a median follow-up of 20 months, 36 patients have relapsed and 21 remain alive in CR. Intensive consolidation with high-dose cytosine arabinoside, amsacrine, and etoposide can modestly prolong DFS compared with historical controls. However, relapse continued to be a major problem and, in addition, with more aggressive consolidation therapy, infection during marrow aplasia resulted in a significant number of deaths.

Acute Disease↗
PubMed1987

Venocclusive disease of the liver after chemoradiotherapy and autologous bone marrow transplantation.

We determined the incidence of venocclusive disease of the liver (VOD) in 96 recipients of autologous bone marrow transplants (BMT) to be 9.4%, a figure less than that reported for allogeneic transplantation. The development of VOD was compared in a cohort of 21 autologous BMT recipients and in 56 randomly chosen, comparably conditioned, concurrent allogeneic BMT recipients. One of these 21 (4.8%) autologous recipients developed VOD, versus 14 of 56 (25%) allogeneic recipients (P less than 0.05). Logistic regression analysis confirmed pretransplant hepatocellular dysfunction as a risk factor for VOD, and suggested that the use of methotrexate and/or cyclosporine contributes to the development of VOD after chemoradiation therapy. However, a graft-versus-host reaction cannot be excluded as a cause of the higher incidence of VOD in allogeneic recipients.

Adolescent↗
PubMed1987

Allogeneic and syngeneic marrow transplantation following high dose dimethylbusulfan, cyclophosphamide and total body irradiation.

Fifty-eight patients received an allogeneic or syngeneic marrow transplant following conditioning with high doses of dimethylbusulfan (DMB), cyclophosphamide (CY) and total body irradiation (TBI). Thirty-two patients had either chronic myeloid leukemia (CML) in accelerated phase or blast transformation, or acute leukemia after first relapse. The actuarial survival of these 32 patients at 3 years was 12% compared with 25% for a group of 206 patients with similar diagnoses prepared for transplantation with CY and TBI alone. This reduced survival was associated with a greater incidence of early non-leukemic deaths, in particular as a result of severe hepatic veno-occlusive disease. The incidence of leukemic relapse was not different in the two groups. Of 13 patients with CML in chronic phase who received syngeneic transplants following DMB, CY and TBI, nine are alive in hematologic and cytogenetic remission from 3.9 to 9.4 (median 6.2) years post-transplant.

Adolescent↗