The artificial pancreas: evaluating risk of hypoglycaemia following errors that can be expected with prolonged at-home use.

AIMS: Artificial pancreas systems show benefit in closely monitored at-home studies, but may not have sufficient power to assess safety during infrequent, but expected, system or user errors. The aim of this study was to assess the safety of an artificial pancreas system emulating the ß-cell when the glucose value used for control is improperly calibrated and participants forget to administer pre-meal insulin boluses. METHODS: Artificial pancreas control was performed in a clinic research centre on three separate occasions each lasting from 10 p.m. to 2 p.m. Sensor glucose values normally used for artificial pancreas control were replaced with scaled blood glucose values calculated to be 20% lower than, equal to or 33% higher than the true blood glucose. Safe control was defined as blood glucose between 3.9 and 8.3 mmol/l. RESULTS: Artificial pancreas control resulted in fasting scaled blood glucose values not different from target (6.67 mmol/l) at any scaling factor. Meal control with scaled blood glucose 33% higher than blood glucose resulted in supplemental carbohydrate to prevent hypoglycaemia in four of six participants during breakfast, and one participant during the night. In all instances, scaled blood glucose reported blood glucose as safe. CONCLUSIONS: Outpatient trials evaluating artificial pancreas performance based on sensor glucose may not detect hypoglycaemia when sensor glucose reads higher than blood glucose. Because these errors are expected to occur, in-hospital artificial pancreas studies using supplemental carbohydrate in anticipation of hypoglycaemia, which allow safety to be assessed in a controlled non-significant environment should be considered as an alternative. Inpatient studies provide a definitive alternative to model-based computer simulations and can be conducted in parallel with closely monitored outpatient artificial pancreas studies used to assess benefit.

Self-efficacy, quality of life, and weight loss in overweight/obese endometrial cancer survivors (SUCCEED): a randomized controlled trial.

OBJECTIVE: More patient-centered programming is essential for endometrial cancer (EC) survivors needing to lose weight to reduce cardiovascular disease risk (CVD). The purpose of this study was to improve self-efficacy (SE) and quality of life (QOL) using a lifestyle intervention program designed for weight loss. METHODS: Overweight and obese early-stage EC survivors, n = 75, were randomized into two groups: 1) Survivors of Uterine Cancer Empowered by Exercise and Healthy Diet (SUCCEED), a six-month lifestyle intervention or 2) a usual care group (UC). Participants completed the Weight Efficacy Lifestyle Questionnaire (WEL) to assess SE and the Functional Assessment of Cancer Therapy-General (FACT-G) to measure QOL, and their body mass index (BMI) was calculated at baseline, 3, 6, and 12 months. Mixed, repeated-measures ANCOVA models with baseline covariates were employed using SPSS 20.0. RESULTS: Positive effects in every WEL domain, including the total score, were statistically significant in the SUCCEED group versus the UC group. A linear regression model demonstrated that, if BMI decreased by 1 unit, the total WEL score increased by 4.49 points. Significant negative correlations were found in the total WEL score and a change in BMI of R = -0.356 (p = 0.006). Between-group differences in the FACT-G were significant from baseline in the fatigue domain at three months (p = .008) and in the physical domain at six months (p = .048). No other significant differences were found. CONCLUSION: Overall, this study shows promise for targeted interventions to help improve SE, thus improving BMI.

On the prediction of SAV transmission among Norwegian aquaculture sites.

Pancreas Disease (PD) is a viral disease that affects Atlantic salmon (Salmo salar) in Norwegian, Scottish and Irish aquaculture. It is caused by salmonid alphavirus (SAV) and represents a significant problem in salmonid farming. Infection with SAV leads to reduced growth, mortality, product downgrading, and has a significant financial impact for the farms. The overall aim of this study is to evaluate the effect of various factors on the transmission of SAV and to create a predictive model capable of providing an early warning system for salmon farms within the Norwegian waters. Using a combination of publicly available databases, specifically BarentsWatch, and privately held PCR analyses a feature set consisting of 11 unique features was created based on the input parameters of the databases. An ensemble model was developed based on this feature set using XG-Boost, Ada-Boost, Random Forest and a Multilayer Perceptron. It was possible to successfully predict SAV transmission with 94.4% accuracy. Moreover, it was possible to predict SAV transmission 8 weeks in advance of a 'PD registration' at individual aquaculture salmon farming sites. Important predictors included well boat movement, environmental factors, proximity to sites with a 'PD registration' and seasonality.

Amount of airflow required for olfactory perception in laryngectomees: a prospective interventional study.

OBJECTIVES: To determine minimum airflow rate required for olfactory stimulation in successfully rehabilitated laryngectomised patients after learning the polite yawning technique (PYT) and to confirm the hypothesis that sense of smell is rehabilitated once the nasal airflow is re-established. DESIGN: Prospective open interventional trial. SETTING: Tertiary academic hospital. PARTICIPANTS: The study population comprised 100 laryngectomised patients. The control group consisted of 100 non-laryngectomised patients of similar age and sex. Rhinomanometry was used to measure air flow in the right and left nostrils, respectively, while the Smell Diskettes Olfaction test (SDOT) was used to test each individual's sense of smell. MAIN OUTCOME MEASURES: The primary endpoint was increasing the airflow, while the secondary endpoint was improvement in the Smell Diskettes Olfaction test score after learning the polite yawning technique. RESULTS: The difference in the Smell Diskettes Olfaction test results before and after introducing the polite yawning technique was statistically significant (F = 53.077; P < 0.001). The number of accurately identified odours increased with each measurement. There was a significant difference among rhinomanometric measurements of airflow through the right (F = 65.002; P < 0.001) and left nostrils (F = 75.465; P < 0.001). Nasal airflow improved with each measurement. The minimum airflow required for olfactory stimulation in successfully rehabilitated patients was approximately 60 cm(3) /s. The control group had considerably better airflow in both nostrils than the laryngectomised group. The difference between the total number of rehabilitated (normosmic) patients (48%) in the laringectomised group and normosmic participants (56%) in the control group (z = 1.132; P = 0.129) was not statistically significant. CONCLUSION: The number of odours identified by laryngectomised patients increased with the volume of nasal airflow. The number of patients with rehabilitated olfactory function approximated the percentage of normosmic individuals in the non-laryngectomised population. These findings confirm the hypothesis that sense of smell is rehabilitated once the nasal airflow is re-established.

Subchronic oral toxicity study of furan in B6C3F1 Mice.

Furan is a heterocyclic organic compound formed during heat treatment for processing and preservation of various types of food. Rodent studies have previously shown that furan is a hepatocarcinogen. Those studies were conducted over a high dose range, which induced tumors at nearly 100% incidence at all doses. This ninety-day gavage study in mice was conducted to extend the dose to a lower range (0.0, 0.03, 0.12, 0.5, 2.0, and 8.0 mg/kg body weight [bw] per day) to identify a no-observed adverse effect level for hepatotoxicity and to characterize non-neoplastic effects, including those affecting clinical biochemistry, hematology, tissue morphology, and histopathology. The liver was the primary target organ with dose-dependent toxicity. Liver weights were increased at the 8.0 mg/kg bw dose in females only. Levels of the serum enzyme alanine transaminase, representative of liver damage, were increased three-fold at the highest dose. Histological changes in the liver were observed at 2.0 and 8.0 mg/kg bw in both sexes. Although clinical parameters were also altered for the kidney, these differences were not accompanied by histological changes. Based on these clinical biochemical and histological changes, a no-observed adverse effect level of 0.12 mg/kg bw per day of furan in mice is suggested.

TRAIL gene-armed oncolytic poxvirus and oxaliplatin can work synergistically against colorectal cancer.

We have explored a unique combination therapy for metastatic colorectal cancer. This strategy combines a potent and new oncolytic poxvirus expressing a membrane-bound tumor necrosis factor-related apoptosis-inducing ligand (TRAIL or TNFSF10) and oxaliplatin (Ox) chemotherapy. We hypothesized that TRAIL expression would increase the efficacy of the oncolytic poxvirus, and that the therapeutic efficacy would be further enhanced by combination with chemotherapy. The cytotoxicity to cancer cells by Ox, oncolytic vaccinia virus (VV) and trail gene-armed VV alone or in combination was tested in vitro. The trail gene armed oncolytic VV-expressed high levels of TRAIL in infected cancer cells and had greater potency as a cytotoxic agent compared with the parent VV. Ox alone exerted concentration-dependent cytotoxicity. In vitro, the combination of the two agents applied at suboptimal concentrations for individual therapy displayed synergy in inducing cancer cells into enhanced levels of apoptosis/necrosis. Western blot analyses were consistent with the notion that TRAIL induced cancer cell death mainly through apoptosis, whereas Ox and vJS6 induced cell death more through non-apoptotic death pathways. In two aggressive colorectal carcinomatosis models derived from human HCT116 and murine MC38 cells, the combination therapy displayed synergistic or additive antitumor activity and prolonged the survival of the tumor-bearing mice compared with either Ox chemotherapy or vvTRAIL-mediated oncolytic gene therapy alone. This combination strategy may provide a new avenue to treating peritoneal carcinomatosis and other types of metastases of colorectal cancer.

Subchronic oral toxicity study of furan in Fischer-344 rats.

Rodent studies have shown that furan is a hepatocarcinogen. Previous studies conducted with high doses showed tumors at nearly 100% incidence at all doses. In this paper, a ninety-day gavage experiment conducted with lower doses (0.0, 0.03, 0.12, 0.5, 2.0, and 8.0 mg/kg bw) to identify a no-observed adverse effect level for hepatotoxicity and to characterize non-neoplastic effects including gross changes and histopathology, clinical biochemistry, hematology, and immunotoxicology is reported. As indicated by changes in serum biomarkers, increased liver weights and gross and histological lesions, the liver is the major target organ affected by furan. There were no changes in body weights, food consumption, or histology in other organs. Some of the serum electrolyte markers, including phosphorus, were altered. There was a significant increase in serum thyroxine and triidothyronine in males. This increase was not accompanied by histological thyroid changes. Immunophenotypic analysis showed that thymic lymphocyte maturation was altered in male rats. Although altered clinical biochemistry and hematological parameters were observed at a dose of > 0.5 mg/kg bw, mild histological lesions in the liver were observed at > 0.12 mg/kg bw. Based on this finding, a furan dose of 0.03 mg/kg bw was proposed as the no-observed adverse effect level for hepatic toxicity.

A 90-day subchronic gavage toxicity study in Fischer 344 rats with 3-methylfuran.

A 90-day gavage study was conducted with 0.0, 0.02, 0.075, 0.25, 1.0 and 4.0 mg/kg bw/day dose groups of 3-methylfuran to identify a no-observed adverse effect level for hepatotoxicity and to characterize non-neoplastic effects including changes in gross anatomy, histopathology, clinical biochemistry and hematology. There were significant changes in the serum clinical biochemistry markers related to liver injury where males were more affected than the females for most parameters analysed. The serum liver injury marker γ-glutamyltransferase, alanine and aspartate aminotransferases were significantly increased in males in the 4.0 mg/kg dose group. Alkaline phosphatase was increased in females and males. There were increases in both gross and histological lesions in the liver of both sexes in addition to statistical differences in female liver weights at the 4.0 mg/kg bw/day dose. Significant increases in spleen weights were found in both genders. This was accompanied by a dose-dependent atrophy of both B- and T-cell regions in which the males were more affected. There were no significant changes in male kidney weights but there was microscopically decreased protein in the proximal tubules and crowding of their nuclei in the 4.0 mg/kg bw/day dose group. There were also significant changes in the kidney serum biomarkers including various electrolytes, blood urea nitrogen, creatinine and uric acid. A small, but significant increase in female kidney weights was observed and which increase was accompanied by changes in electrolytes, kidney specific markers and a dose-dependent increase in mineralization. In both genders, amylase decreased whereas lipase increased but these were not accompanied by any histological changes in the pancreas. Histopathological changes in the liver were observed consistently in male and female rats in the 0.25 mg/kg dose group and higher. Hence, a lowest observed adverse effect level (LOAEL) of 0.25 mg/kg bw/d and a no observed adverse effect level (NOAEL) of 0.075 mg/kg bw/day are proposed for 3-methylfuran-induced hepatic lesions in this study. Benchmark dose modelling based on a BMR of 10% change in lesion incidence, generated BMDLs10 of 0.08 mg/kg bw/day in male rats and 0.05-0.17 mg/kg bw/day in female rats for increased incidence of liver lesions.

Responding to mental health statutory drivers: experience of a low intensity cognitive behavioural therapy programme.

OBJECTIVES: Stress control (SC), a brief psycho-education course, was implemented to increase access to psychological therapies in line with Northern Irish mental health service statutory drivers. The first aim of this study was to gauge the efficacy of SC in a robust manner with clinical significance testing. The second aim was to assess whether demographics traditionally 'hard-to-reach' - males, younger adults and those from deprived areas - accessed SC. The third aim was to elucidate what prompted their access and the experiences of attendees at SC. METHODS: Attendees at SC were 170 adults over six iterations of the course. Pre- and post-questionnaires included the Depression Anxiety Stress Scales - 21, captured demographic details and qualitative feedback, which was subject to a mixed-methods analysis. RESULTS: SC attendees reported significant decreases on depression, anxiety and stress sub-scales post-intervention. Moreover, 38.71% (n=36) of attendees who completed SC exhibited clinically significant improvement afterwards on one or more sub-scale. Attendance figures for males, younger adults and those classified as socioeconomically deprived were modest. Patterns within the data suggested prospective success for targeting these cohorts. CONCLUSIONS: SC attracted people in need of mental healthcare input and affected quantifiable change within those people's lives, while satisfying statutory demands for service delivery in an accessible community context. Recommendations to increase engagement with those traditionally 'hard-to-reach' for psychological services are provided, which, if implemented, have the potential to achieve further compliance with Northern Irish mental health statutory drivers.

A comparison in individual murine tumors of techniques for measuring oxygen levels.

PURPOSE: To investigate the relationship between different techniques for measuring oxygen levels in a murine tumor model. METHODS AND MATERIALS: Using the murine fibrosarcoma line KHT-C, five techniques of measuring oxygen levels-the Eppendorf pO2 Histograph, EF5 binding, the comet assay, a paired survival assay, and an in vivo growth delay assay-were assessed. In these experiments, three or more techniques were applied in different combinations to measure the oxygen levels in individual tumors. RESULTS: Statistically significant correlations were observed between the hypoxic proportions calculated from the paired survival assay with those from EF5 binding. The comet assay was found to have a statistically significant correlation with the paired survival analysis and the growth delay analysis. No statistically significant correlation was found between the Eppendorf pO2 Histograph measurements and those from the other techniques, although there were weak correlations with the paired survival assay and EF5 binding. For technical reasons, a comparison was not made between EF5 binding and the growth delay assay. CONCLUSIONS: The correlations found between EF5 binding and the comet assay with the radiobiological assays suggest that these techniques have potential for predicting outcome following radiation treatment. The lack of correlation seen between the pO2 Histograph data and the radiobiological assays is in contrast to results from early clinical trials.

Heterogeneity of tumor oxygenation: relationship to tumor necrosis, tumor size, and metastasis.

PURPOSE: Measurements of oxygenation in the transplanted rodent KHT-C and SCC-VII tumors demonstrate significant heterogeneity from tumor to tumor as is observed in human tumors. This finding suggests that heterogeneity in oxygenation between tumors is likely related to factors associated with tumor growth rather than to intrinsic genetic differences. In this study we examined whether measurements of the oxygenation of individual KHT-C tumors were related to necrosis in the tumors or to tumor size and whether the more hypoxic tumors gave rise to more metastases. METHODS: Tumors were grown in the gastrocnemius muscle of C3H mice and tumor oxygenation was measured at defined sizes (approx. 0.35 g, 1.0 g, and 2.0 g) using an Eppendorf polarographic oxygen probe. Necrosis was assessed by examining histological sections cut from tumors used for the oxygen measurements. Metastasis was assessed by counting macroscopic lung nodules in mice sacrificed when their tumors reached a size of approximately 2 g. RESULTS: Tumor oxygenation in individual KHT-C tumors became poorer and necrosis became more extensive as the tumors grew larger but, at a size of 0.3-0.4 g, there was no relationship between oxygenation and extent of necrosis. In general, measurements of tumor pO2 at a size of 0.3-0.4 g were predictive of tumor PO2 in the same tumor at a size of about 1 g, but by the time the tumors reached a size of about 2 g they were all very hypoxic. There was a trend suggesting a relationship between macroscopic metastases in the lung and degree of hypoxia in the KHT-C tumors but this was not statistically significant. CONCLUSION: The results indicate that the heterogeneity of oxygenation seen in KHT-C tumors is not explained by different degrees of necrosis in the individual tumors. The lack of a correlation between increased metastasis formation and increased levels of hypoxia in the KHT-C tumors is not consistent with results reported for human tumors.

The immunological characterization of human antibodies to factor VIII isolated by immuno-affinity chromatography.

Nine human antibodies to factor VIII were isolated from haemophilic plasmas by affinity chromatography and gel filtration and six were subsequently subjected to immunological characterization. Three partially purified preparations were similarly characterized. Eight of the antibodies were characterized as being exclusively IgG and one preparation was found to contain IgM. Seven of the antibodies contained only a single light chain type, four being of type lambda and three of type kappa. Two antibody preparations contained both kappa and lambda light chains. In four of the preparations, only a single heavy chain sub-class could be demonstrated, three of IgG3 and one of IgG4. Of the remainder, three were a mixture of IgG3 and IgG4 sub-classes and one contained both IgG2 and IgG4. IgG sub-classification could not be achieved with the IgM-containing preparation. These results demonstrate a restricted heterogeneity of light and heavy chains in human antibodies to factor VIII.

Studies on human factor VIII and its antibodies using radiolabelling and affinity chromatography.

An immuno-affinity chromatography methods was used to isolated human factor VIII and its antibodies and the mechanism of the affinity system was investigated using iodine labelling. Rabbit antibodies to human factor VIII were insolubilised onto CNBr - activated Sepharose 2B which was used for the preparation of affinity columns. Both VIII:C and VIIIR:Ag were adsorbed onto such columns from factor VIII preparations. The subsequent application of immunoglobulin preparations containing human antibodies to factor VIII resulted in the adsorption of these antibodies onto the columns. Adsorbed material was eluted from the affinity columns with 0.2 M glycine - HCl, pH 2.3. When 125I-labelled factor VIII and 131I-labelled human antibodies to factor VII were used in this affinity system, the eluted material could be separated into three fractions by gel filtration on Bio-Gel A 1.5 m. Fraction 1 occurred at the void volume position, fraction 3 at a position corresponding to the elution position of IgG and fraction 2 at an intermediate position. 131I-labelled material was present in all three peaks. 125I-labelled material was present mainly in peak 1, with a little in peak 2. The results support the view that VIIIR:Ag, which binds heterologous antibodies, is non-covalently linked to a smaller subunit, VIII:C, which binds homologous antibodies.

New developments in sustained-release antihypertensive therapy: formulation and pharmacokinetic considerations.

In order to achieve a consistently absorbed form of nifedipine over 24 hours, a novel formulation approach, INDAS, was used to develop a once-daily, sustained-release (SR) form of nifedipine that could provide effective control of blood pressure at a low total daily dose. The pharmacokinetic characteristics of this new formulation of nifedipine-SR were compared with those of divided doses of conventional nifedipine. The SR formulation was shown to achieve a lower peak plasma nifedipine level but with a prolonged plasma profile characterized by an extended time to peak plasma levels (Tmax), a higher trough plasma level, a longer apparent half-life, and a markedly lower peak-to-trough fluctuation in plasma nifedipine concentrations. In a separate study, the gastrointestinal transit parameters and physical characteristics of the SR tablet were evaluated. This study established that the large intestine is the major site of residence and absorption for this dosage form. The physical erosion and disintegration characteristics of the SR formulation are such that a well-maintained absorption of nifedipine is consistently achieved over the 24 hour dosing interval.

Effect of ABT-627 (A-147627), a potent selective ET(A) receptor antagonist, on the cardiopulmonary profile of newborn lambs with surgically-induced diaphragmatic hernia.

1. Postnatal mortality in isolated congenital diaphragmatic hernia (CDH) is mainly related to the associated pulmonary hypertension (PH) and to right-to-left shunting. 2. Endothelins (ETs) are potent vasoconstrictors and pro-mitogenic peptides. Strong evidences support their participation in CDH and in the etiology of PH via the activation of ET(A) receptors (ET(A)-Rs). 3. Evaluation of the effect of ABT-627, a selective non-peptidic ET(A)-R antagonist, given from -15 to 210 min post-delivery (1 mg kg(-1) bolus +0.01 mg kg(-1) h(-1) infusion, i.v.), was conducted in the lamb model of CDH. 4. Severity of CDH was assessed in comparison to untreated controls (n=5). Untreated CDH lambs (n=7) had a higher mean pulmonary arterial pressure (MPAP; P<0.0001), lower mean blood pressure (MBP; P=0.0004), higher MPAP / MBP ratio (P<0.0001), lower arterial pH (P<0.0001), higher paCO(2) (P<0.0001), lower paO(2) (P<0.0001) and lower post-ductal pulsatile SaO(2) (P<0.0001) than untreated controls. 5. Treated controls (n=7) showed a higher MPAP, lower MBP, higher MPAP/MBP ratio, lower arterial pH, higher paCO(2), lower paO(2), lower post-ductal pulsatile SaO(2) and lower plasmatic ir-ET ratios compared to untreated controls (P<0.0001). 6. Treated CDH lambs (n=8) showed a higher MBP (P<0.0001), lower MPAP / MBP ratio (P<0.0001), higher arterial pH (P<0.0001), lower paCO(2) (P<0.0001), higher paO(2) (P=0.0228), higher post-ductal pulsatile SaO(2) (P=0.0016) and lower plasmatic ir-ET ratios (P=0.0247) when compared to untreated CDH lambs. 7. These observations revealed that, although acute perinatal treatment with a selective non-peptidic ET(A)-R antagonist had some adverse effects in controls, it attenuated the progressive cardiopulmonary deterioration that occurred after birth in CDH lambs.

Oxygenation predicts radiation response and survival in patients with cervix cancer.

BACKGROUND AND PURPOSE: Hypoxia appears to be an important factor in predicting tumor relapse following radiation therapy. This study measured oxygenation prior to treatment in patients with cervix cancer using a polarographic oxygen electrode to determine if oxygenation was an important prognostic factor with regard to tumor control and survival. MATERIALS AND METHODS: Between May 1994 and June 1997, 74 eligible patients with cervix cancer were entered into an ongoing prospective study of tumor oxygenation prior to primary radiation therapy. All patients were evaluated with an Eppendorf oxygen electrode during examination under anesthesia. Oxygenation data are presented as the hypoxic proportion, defined as the percentage of pO2 readings of <5 mm Hg (abbreviated as HP5). RESULTS: The HP5 ranged from 2 to 99% with a median of 52%. With a median follow-up of 1.2 years, the disease-free survival (DFS) rate was 69% for patients with HP5 of < or =50% compared with 34% for those with HP5 of >50% (log-rank P = 0.02). Tumor size above and below the median of 5 cm was also significantly related to DFS (P = 0.0003) and patients with bulky hypoxic tumors had a significantly lower DFS (12% at 2 years) than either bulky oxygenated or non-bulky oxygenated or hypoxic tumors (65%, P = 0.0001). CONCLUSIONS: Hypoxia and tumor size are significant adverse prognostic factors in a univariate analysis of disease-free survival in patients with cervix cancer. A high risk group of patients with bulky hypoxic tumors have a significantly higher probability of relapse and death.

The use of needle biopsies for radiobiological assessment of oxygen levels in KHT-C tumors.

Hypoxia affects the sensitivity of cells to radiation. Hence there is considerable interest in the development and assessment of techniques for measuring oxygen levels. In the work described here, we explore the use of tumor needle biopsies (fine needle aspirates) in an assay that is standard in the field of radiation biology: the paired survival assay. We found that needle biopsies are a feasible option for estimating cell survival when conducting this assay, and that the variability in cell survival between tumors was greater than that between different biopsies from the same tumor. Using this technique, we then compared measurements of tumor hypoxia using the paired survival assay and the growth delay assay in the same individual tumors. We found a significant correlation between these two techniques.

Detection of hypoxic fractions in murine tumors by comet assay: comparison with other techniques.

The alkaline comet assay was used to detect the hypoxic fractions of murine tumors. A total of four tumor types were tested using needle aspiration biopsies taken immediately after a radiation dose of 15 Gy. Initial studies confirmed that the normalized tail moment, a parameter reflecting single-strand DNA breaks induced by the radiation, was linearly related to radiation dose. Further, it was shown that for a mixed population (1:1) of cells irradiated under air-breathing or hypoxic conditions, the histogram of normal tail moment values obtained from analyzing 400 cells in the population had a double peak which, when fitted with two Gaussian distributions, gave a good estimate of the proportion of the two subpopulations. For the four tumor types, the means of the calculated hypoxic fractions from four or five individual tumors were 0.15 +/- 0.04 for B16F1, 0.08 +/- 0.04 for KHT-LP1, 0.17 +/- 0.04 for RIF-1 and 0.14 +/- 0.01 for SCCVII. Analysis of variance showed that the hypoxic fraction in KHT-LP1 tumors is significantly lower than those of the other three tumors (P = 0.026) but that there is no significant difference in hypoxic fraction between B16F1, RIF-1 and SCCVII tumors (P = 0.574). Results from multiple samples taken from each of five RIF-1 tumors showed that the intertumor heterogeneity of hypoxic fractions was greater than that within the same tumor. The mean hypoxic fraction obtained using the comet assay for the four tumor types was compared with the hypoxic fraction determined by the clonogenic assay, or median pO2 values, or [3H]misonidazole binding in the same tumor types.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparing techniques of measuring tumor hypoxia in different murine tumors: Eppendorf pO2 Histograph, [3H]misonidazole binding and paired survival assay.

Using five transplantable murine tumors (SCC-VII, B16F1, KHT-C, KHT-LP1, RIF-1), measurements of tumor hypoxia have been made with two techniques which have the potential to be used for assessing oxygenation in human tumors (the Eppendorf pO2 Histograph and binding of [3H]misonidazole) and have been compared with an established radiobiological technique, the paired survival assay. There were significant differences in the pO2 measurements made in individual tumors both within and between the five different tumor types. Significant differences between the tumor types were also found for the [3H]misonidazole binding. A correlation was observed between the mean values of the hypoxic proportion as measured by the paired survival assay and the mean binding of [3H]misonidazole as measured by both tumor activity in dpm/100 mg tissue (r = 0.94, P = 0.02) and the tumor-to-muscle activity ratio (r = 0.87, P = 0.06). No biologically significant correlation was seen between the mean values of the hypoxic proportion from anesthetized mice as measured by the paired survival assay (range 20-58%) and the pooled Eppendorf pO2 Histograph measurements made on groups of tumors. These results with the Eppendorf pO2 Histograph are similar to those reported by others. When both Eppendorf pO2 Histograph measurements and paired survival measurements were made on the same individual KHT-C tumors, it was again found that there was no correlation between the two measurements of hypoxia.

Plasma glucose and insulin responses to oral and intravenous glucose in cold-exposed humans.

Although glucose tolerance and skeletal muscle glucose uptake are markedly improved by cold exposure in animals, little is known about such responses in humans. This study used two variations of a glucose tolerance test (GTT) to investigate changes in carbohydrate metabolism in healthy males during nude exposure to cold. In experiment 1, an oral GTT was performed in the cold and in the warm (3 h at 10 or 29 degrees C). To bypass the gastrointestinal tract, and to suppress hepatic glucose output, a second experiment was carried out as described above, using an intravenous GTT. Even though cold exposure raised metabolic rate greater than 2.5 times, plasma glucose and insulin responses to an oral GTT remained unaltered. In contrast, cold exposure reduced the entire plasma glucose profile as a function of time during the intravenous GTT (P less than 0.05), as plasma glucose was returned to basal levels within 1 h in comparison to a full 2 h in the warm, despite low insulin levels. The results of the intravenous GTT demonstrate that even with low insulin levels, carbohydrate metabolism is increased in cold-exposed males. This effect could be masked in the oral GTT by gastrointestinal factors and a high hepatic glucose output. Cold exposure may enhance insulin sensitivity and/or responsiveness for glucose uptake, mainly in shivering skeletal muscles.