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PubMed1989

Oral absorption of sodium pentobarbital and effects on gastrointestinal function.

An anaesthetic dose (40 mg/kg) of sodium pentobarbital (SP) was administered intragastrically to adult, fasted male rats at total dosing volumes of 1, 2, or 3 ml. Area under the plasma concentration-time curve did not differ for the various dosing volumes. During the initial (rapid) phase of gastric emptying all solutions containing drug appeared to empty at a faster rate than distilled water (2 ml). However, solutions containing drug emptied much more slowly than water during the terminal (slow) phase of gastric emptying. Drug solutions moved along the small intestine at approximately the same rate as distilled water. SP significantly lowered rectal temperature and slowed the propagation velocity of the migrating myoelectric complex (MMC) recorded from four serosal electrodes chronically implanted along the proximal small intestine. In addition, the drug significantly decreased the rate of MMC recurrence, extended the duration of MMC phases, and decreased slow wave frequency at all sites monitored. The results suggest that: 1) the relative oral bioavailability of sodium pentobarbital is not influenced by dosing volume within the range tested, 2) the various dosing volumes of SP tested moved through the gastrointestinal tract at an equal rate, and 3) orally administered SP significantly decreases the propagation velocity and periodicity of the MMC in the small intestine.

Administration, Oral↗
PubMed2006

A prospective, randomized trial comparing conventional transurethral prostate resection with PlasmaKinetic vaporization of the prostate: physiological changes, early complications and long-term followup.

PURPOSE: We compared standard transurethral prostate resection with bipolar PlasmaKinetic prostate vaporization for bladder outflow obstruction using a Gyrus PlasmaKinetic Plasma V bar. MATERIALS AND METHODS: A total of 160 men were enrolled in a prospective, randomized trial. Those at higher risk for cancer were excluded by prostate specific antigen and digital rectal examination with or without transrectal ultrasound biopsy. A total of 81 men underwent prostate vaporization and 79 underwent transurethral prostate resection. Preoperative International Prostate Symptom Score and quality of life score, uroflowmetry, post-void residual urine and transrectal ultrasound prostate volume were recorded. Preoperative and postoperative serum hemoglobin, hematocrit and sodium were measured. Perioperative fluid absorption was calculated using weighing on table and blood loss using the Hemocue system. Longer followup of International Prostate Symptom Score and quality of life score, uroflowmetry and post-void residual urine was available in 149 men, including 76 who underwent prostate vaporization and 73 who underwent transurethral prostate resection. Data were analyzed using the 1 or 2-sample t and chi-square tests. RESULTS: The 2 groups were comparable in all preoperative parameters. Perioperative fluid absorption, intraoperative blood loss, preoperative and postoperative serum hematocrit, and sodium changes were not statistically different. Mean resection time was 4 minutes shorter for transurethral prostate resection (28.5 vs 32.6 minutes, p = 0.08). Patients with transurethral prostate resection showed a greater hemoglobin decrease (1.39 vs 0.8 gm/dl, p = 0.002) and required more irrigation postoperatively (28.3 vs 20.4 l, p = 0.001). Four patients with transurethral prostate resection required transfusion compared with none who underwent prostate vaporization. After transurethral prostate resection hospital stay was longer (3.36 vs 3.02 days, p = 0.03). Cancer was detected in 8 patients with transurethral prostate resection (10%), of whom 7 are under prostate specific antigen surveillance and 1 received radical radiotherapy. Mean long-term followup was 258 days (range 82 to 884). Prostate vaporization and transurethral prostate resection were equally effective at followup, as evidenced by changes in maximum urine flow, International Prostate Symptom Score, quality of life score and post-void residual urine. CONCLUSIONS: The 2 operations are highly effective in experienced hands. PlasmaKinetic prostate vaporization resulted in less postoperative bleeding and a slightly shorter hospital stay. The lack of a histological specimen with this version of PlasmaKinetic prostate vaporization may mean that clinically significant cancers are missed.

Adult↗
PubMed1982

An unusual type of cytokeratin filament in cells of a human cloacogenic carcinoma derived from the anorectal transition zone.

Epithelia-derived tumors (carcinomas) can be distinguished from mesenchymally derived tumors by the presence of intermediate-sized filaments of the cytokeratin type, which usually coincides with the absence of other types of intermediate-sized filaments such as vimentin filaments. In the course of diagnostic examinations of human tumors, using immunofluorescence microscopy, we have come across a case of an unusual carcinoma (Primary tumor and lymph node metastasis) positively stained not only with cytokeratin antibodies but also with immunoglobulins present in vimentin antisera. Therefore, this tumor, a cloacogenic carcinoma apparently derived from the rectal-anal transitional region, has been examined in greater detail using both immunofluorescence microscopy and immuno-electron microscopy as well as gel electrophoretic analysis of cytoskeletal polypeptides from total tumor tissue and from microdissected nodules enriched in carcinoma cells. The unusual reaction of the carcinoma cells with immunoglobulins present in seven different (rabbit or guinea pig) antisera raised against vimentin, has been found to be diminished after absorption on purified cytokeratin or total epidermal cytoskeletal material, but not after absorption on purified vimentin. Gel electrophoretic analysis of tumor cytoskeletons showed an unusual complex pattern of cytokeratin polypeptides containing relatively large (Mr 68,000 and Mr 58,000) neutral-to-slightly basic cytokeratins, as are typically found in epidermis and other stratified squamous epithelia, as well as several smaller acidic cytokeratins, including a Mr 40,000 polypeptide found in certain nonstratified epithelial such as colon and small intestine. Total tumor also showed the inclusion of some vimentin which, however, was significantly decreased in analysis of excised carcinoma nodules. Examining antibody binding to polypeptides separated by gel electrophoresis and blotted on nitrocellulose paper, we have found that antisera raised against vimentin contained not only vimentin antibodies but also immunoglobulins which specifically bound to the largest cytokeratin component. We conclude that the unusual reaction of immunoglobulins present in vimentin antisera with cytokeratin filament bundles does not represent specific binding to vimentin in these carcinoma cells, but is due to a component obviously widespread in vimentin antisera which binds specifically to a cytokeratin present in this type of tumor but not in most other carcinomas. It is proposed that use is made in diagnostic examinations of vimentin antisera or affinity-purified vimentin antibodies that have been pre-absorbed on cytokeratin protein, in order to eliminate such disturbing reactions.

Aged↗
PubMed1995

[Preliminary results using a combined xylose absorption/hydrogen exhalation test in horses].

In the present study the breath hydrogen (H2) excretion test was combined with the xylose absorption test in 4 normal horses and 9 clinical patients with chronic diarrhea (n = 3) or chronic weight loss without diarrhea (n = 6). All horses underwent a thorough clinical examination. Laboratory evaluations consisted of haematology and serum biochemistry as well as bacteriological and parasitological examination of feces. In addition, serum electrophoresis and abdominocentesis was performed in all the clinical patients. Gastroscopy was carried out in 6 patients and rectal biopsies were obtained from 4 animals. Two animals were euthanized within 4 weeks after the evaluation. The diagnosis of chronic granulomatous enteritis was confirmed in one of them at necropsy, the cause of weight loss in the other remained unexplained. In the remaining animals, specific causes such as management, parasites, chronic infections and diseases of liver, kidneys and heart were excluded, but no specific diagnosis could be obtained. For the combined xylose absorption/H2 excretion test, the animals were starved overnight and given 0.5/kg/bwt xylose as a 10% solution by stomach tube the next morning. Blood samples were collected for plasma xylose analysis at 30 min intervals for 4 hrs, and breath samples were also collected at 30 min intervals for 8 hrs. With the exception of the animal with granulomatous enteritis, the diseased horses showed only slight alterations in either peak concentrations or times to reach peak levels of plasma xylose. None of the healthy animals showed an increase in breath H2 production after xylose administration, whereas five of the diseased animals showed distinct increases of variable heights. In addition, the diseased horses showed higher fasting breath H2 levels (range 7.5-61.5 ppm) than normal horses (range 0-5 ppm). It is concluded that gastrointestinal disorders might be influenced or even induced by a change in intestinal microbial composition, as evidenced by an increased hydrogenic metabolism.

Animals↗
PubMed1978

Preliminary in vitro and in vivo investigations on methylprednisolone and its acetate.

Sodium fluoride (6--8 mg/ml) inhibits hydrolysis of methylprednisolone acetate to methylprednisolone. An HPLC method for simultaneous determination of hydrocortisone, methylprednisolone and methylprednisolone acetate in plasma is presented. Analysis of plasma samples (containing NaF) for methylprednisolone acetate shows no significant change in concentration over extended periods of storage at -20 degrees C. In vitro hydrolysis of methylprednisolone acetate at 37 degrees C in human whole blood is rapid (average t1/2 = 19 min). In one cat, the bioavailabilities of methylprednisolone acetate rectally was 13% and of methylprednisolone (alcohol) rectally was 26%, relative to intravenous administration of methylprednisolone. In the same cat, the bioavailabilities of methylprednisolone acetate orally was 93% and of methylprednisolone was 82%, relative to intravenous administration of methylprednisolone. All samples collected after oral administration of methylprednisolone acetate to a human subject were found to contain only methylprednisolone (alcohol) indicating hydrolysis of the drug during absorption through the gastrointestinal membrane and/or in the liver. If the ester had the same half-life in blood in vivo as measured in vitro, it would have been measurable in plasma.

Acetates↗
PubMed1989

Emergence of Na+-glucose cotransport in an epithelial secretory cell line sensitive to cholera toxin.

Epithelial properties and effects of cholera toxin (CT) and glucose were investigated in human rectal tumor cell line HRT-18. Addition of 10(-3) M dibutyryl adenosine 3',5'-cyclic monophosphate (DbcAMP), 10(-8) M vasoactive intestinal peptide, 10(-5) M epinephrine, and 10(-5) M forskolin to the serosal side and of 3.5 micrograms/ml CT to the mucosal side and of 2 micrograms/ml A23187 to both the serosal and mucosal sides raised short-circuit current (Isc). This rise was reversed by serosal addition of 5 x 10(-5) M bumetanide or 10(-4) M ouabain. In filters treated with CT, Isc and net chloride flux (JClnet) increased after 60 min from 0.05 +/- 0.008 and -0.04 in the Ringer to 0.32 +/- 0.05 and -0.33 mueq.h-1.cm-2, respectively. Addition of 10(-2) M glucose further raised Isc by stimulating net sodium flux (JNanet) (0.70 +/- 0.08 and + 0.58 mueq.h-1.cm-2, respectively). This additional augmentation of Isc was reversed by 0.5 mM phlorizin and was mimicked by 3-O-methyl-D-glucose. When the filters were stimulated by cAMP for 15 min, Isc was also enhanced by addition of glucose. In untreated filters, Isc, JNanet, and JClnet did not differ significantly before and after addition of glucose. It is concluded that HRT-18 cells in basal state do not display absorptive properties but secretory properties stimulated by CT. However they exhibit Na+-glucose cotransport once stimulated by either CT or cAMP.

Adenocarcinoma↗
PubMed2000

Absorption of lefradafiban from different sites of the gastrointestinal tract.

AIMS: Fibrinogen receptor antagonists show a close relationship between plasma concentrations and inhibitory effect. Optimal efficacy at an acceptable bleeding risk requires low inter- and intrasubject variability on low peak trough fluctuation in receptor occupancy and therefore also of plasma concentrations. Therefore, the enteral absorption of lefradafiban, an orally available fibrinogen receptor antagonist prodrug, was investigated after local administrations to different sites of the gastrointestinal tract in order to investigate the feasibility of an oral extended release formulation. METHODS: Twelve healthy male subjects received in a randomised, open-labelled, four-period crossover trial four consecutive administrations of lefradafiban: 1. orally; 2. administration into the jejunum, 3. administration into the lower jejunum/ileum (300 cm distally to the teeth), and 4. administration into the lumen of the sigmoid region (30 cm proximally to the anus). Local intestinal administrations were performed through a gastrointestinal tube. RESULTS: Compared with oral administration, ratios [mean (two-sided 90% confidence intervals)] of maximum drug plasma concentrations and AUC(0,24 h) of fradafiban were 1.05 (0.80, 1.39) and 1.06 (0.85,1.31) after jejunal, 0.98 (0.75,1.30) and 0.98 (0.79,1.21) after ileal, 0.52 (0.39,0.69) and 0.68 (0.55,0.85) after colonic administration. Urinary excretion of fradafiban was about 16% of the dose after oral, jejunal and ileal applications whereas after rectal administration about 11% were excreted. CONCLUSIONS: Lefradafiban is absorbed throughout the entire gastrointestinal tract. Therefore, an extended release formulation seems to be feasible with regard to bioavailability.

Administration, Oral↗
PubMed1980

Bioavailability of theophylline following a rectally administered concentrated aminophylline solution.

A two-way complete crossover bioavailability study of solutions of theophylline given orally or rectally in 16 healthy subjects was conducted. Blood samples were obtained prior to dosing and at 0.25, 0.5, 0.75, 1, 1.5, 2, 2,5, 3, 3,5, 4, 4.5, 5, 6, 7, 8, 10, 12, and 24 hr. Plasma theophylline was determined by high-pressure liquid chromatography. In the fasting subjects solutions given orally were absorbed faster (0.95 versus 1.95 hr to peak), reaching a higher peak concentration (7.26 versus 4.87 microgram/ml) than the solutions given rectally. Depending on the method of computation, solutions given rectally were estimated to be 86% to 87% as biovailable as the solutions given orally, with 75% of the subjects having 80% or greater relative bioavailability.

Absorption↗
PubMed2005

Colonic spread and serum pharmacokinetics of budesonide foam in patients with mildly to moderately active ulcerative colitis.

BACKGROUND: Local treatment with foams in patients suffering from ulcerative proctitis or proctosigmoiditis is considered a rational treatment option. AIMS: To investigate colonic spread, safety, tolerability and acceptance of a newly developed budesonide foam formulation. METHODS: Twelve patients (four females, eight males) with acute proctosigmoiditis or left-sided ulcerative colitis were rectally administered a single dose of [99Tcm]-labelled budesonide foam (Budenofalk; Dr Falk Pharma GmbH, Freiburg, Germany) containing 2 mg budesonide in 20 mL foam after diagnostic colonoscopy. Thereafter, the colonic spread was assessed by means of gamma-scintigraphy for 6 h. Serum samples were taken simultaneously. RESULTS: Budesonide foam spread with a maximum between 11 and 40 cm, thus reaching the sigmoid colon in all patients. In some patients, the foam even extended into the distal third and the middle of the descending colon with maximum radioactivity at 4 h. Systemic budesonide absorption was rapid and pharmacokinetic data were comparable with published data on marketed budesonide enemas, with mean serum C(max) and AUC(0-8 h) values of 0.8 +/- 0.5 ng/mL and 3.7 +/- 1.9 ng h/mL, respectively. The new formulation was well accepted by all patients, who could retain the foam for at least 4 h. CONCLUSIONS: In the majority of patients, budesonide foam effectively spread up to the left-sided colon and thus qualifies for the local treatment of proctosigmoiditis.

Administration, Rectal↗
PubMed1991

Direct measurement of first-pass ileal clearance of a bile acid in humans.

The purpose of this study was to develop and validate a method of directly measuring ileal bile acid absorption efficiency during a single enterohepatic cycle (first-pass ileal clearance). This has become feasible for the first time because of the availability of the synthetic gamma-labeled bile acid 75Selena-homocholic acid-taurine (75SeHCAT). Together with the corresponding natural bile acid cholic acid-taurine (labeled with 14C), SeHCAT was infused distal to an occluding balloon situated beyond the ampulla of Vater in six healthy subjects. Completion of a single enterohepatic cycle was assessed by obtaining a plateau for 75SeHCAT activity proximal to the occluding balloon, which prevented further cycles. Unabsorbed 75SeHCAT was collected after total gut washout, which was administered distal to the occluding balloon. 75SeHCAT activity in the rectal effluent measured by gamma counter was compared with that of absorbed 75SeHCAT level measured by gamma camera and was used to calculate first-pass ileal clearance. This was very efficient (mean value, 96%) and showed very little variation in the six subjects studied (range, 95%-97%). A parallel time-activity course in hepatic bile for 14C and 75Se during a single enterohepatic cycle, together with a ratio of unity for 14C/75Se in samples obtained at different time intervals, suggests that 75SeHCAT is handled by the ileum like the natural bile acid cholic acid-taurine. Extrapolation of 75SeHCAT first-pass ileal clearance to that of the natural bile acid therefore seems justifiable. In a subsidiary experiment, ileal absorption efficiency per day for 75SeHCAT was also measured by scanning the gallbladder area on 5 successive days after the measurement of first-pass ileal clearance. In contrast with absorption efficiency per cycle, absorption efficiency per day varied widely (49%-86%), implying a possible wide variation in recycling frequency per day.

Adult↗
PubMed1988

[Results of a study of the resorption of bufexamac following rectal administration].

12 patients suffering from hemorrhoidal complaints were treated with hemorrhoidal suppositories containing Proctoparf-bufexamac. Using the HPCL method, we measured the concentrations of bufexamac in the serum after 30, 45 and 60 minutes as well as after 2, 3, 6, 7.5 and 20 hours. Neither bufexamac nor its major metabolite (4-butoxyphenyl acetic acid) could be detected in concentrations above 0.2 micrograms/ml and 0.5 micrograms/ml, respectively. These results prove that the application of Proctoparf suppositories is not associated with any significant systemic absorption of bufexamac.

Bufexamac↗
PubMed1997

Retrograde colonic spread of a new mesalazine rectal enema in patients with distal ulcerative colitis.

BACKGROUND: Rectal treatment with mesalazine enemas is the first-line therapy for distal ulcerative colitis. In order to improve the benefits of rectal therapy, a new 60 mL 5-ASA rectal gel enema preparation has been developed using a device which excludes direct contact of the inert propellant gas with the active drug. The purpose of the present study was to assess by scintigraphy the colonic distribution of this new mesalazine rectal gel enema. METHODS: Twelve patients with active ulcerative colitis were administered 4 g of the mesalazine rectal enema labelled with 100 MBq technetium sulphur colloid (99mTc-SC). Anterior scans of the abdomen were acquired at intervals for 4 h. Scans were analysed to evaluate the extent of retrograde flow and homogeneity of distribution of the radiolabelled enema in the rectum, sigmoid, descending and transverse colon. In addition, plasma levels of 5-ASA and Ac-5-ASA were measured for 6 h. RESULTS: All patients retained the entire rectal gel throughout the course of the study without reporting adverse events. In 11 out of 12 patients (92%) the gel had spread homogeneously beyond the sigmoid colon and had reached the upper limit of disease in all cases. The maximum spread (splenic flexure) was observed in 6 out of 12 patients (50%) within the first 2 h. The systemic absorption of mesalazine and its metabolite Ac-5-ASA was low. CONCLUSIONS: The new mesalazine enema represents an adequate alternative and a further technological improvement in the topical treatment of distal ulcerative colitis.

Adult↗
PubMed1985

Methohexital plasma concentrations in children following rectal administration.

Despite the increasing use of rectal methohexital as a premedicant-induction agent in pediatric anesthesia, there are no data to confirm the assumption that low plasma methohexital concentrations are the cause of inadequate sedation of children and that high concentrations are associated with the loss of consciousness. Plasma methohexital concentrations were determined in 20 ASA Class I children, ages 2-7 yr, after the rectal administration of methohexital (25 mg/kg). Seventeen of the 20 children in this study fell asleep after receiving the drug and achieved peak plasma concentrations greater than 2 micrograms/ml. The maximum plasma methohexital concentration in children that did not fall asleep was less than 2 micrograms/ml. The mean time to the onset of sleep after drug administration was 8.3 min (at which time the mean plasma concentration was 4.4 micrograms/ml). The mean peak plasma concentration and the mean time to peak plasma concentration were 4.7 micrograms/ml and 13.9 min, respectively. Loss of consciousness after rectal administration of methohexital correlates well with the plasma concentration of the drug.

Anesthesia, Inhalation↗
PubMed1994

Clinical and pharmacokinetic study of praziquantel in Egyptian schistosomiasis patients with and without liver cell failure.

The pharmacokinetics and therapeutic efficacy of praziquantel (Distocide; Epico, El-Asher-Men-Ramadan City, Egypt) were studied in 40 patients with schistosomiasis mansoni and various degrees of hepatic dysfunction. The patients were allocated into four groups: the first included 10 patients with simple active schistosomiasis while the other three were made up of patients with schistosomiasis associated with liver cirrhosis and splenomegaly according to Child's classification of hepatocellular function. Every patient was treated with 40 mg/kg of praziquantel as a single oral dose. The efficacy of the drug was evaluated after two months by rectal snip examination. The pharmacokinetic parameters did not differ significantly between patients with simple active schistosomiasis (group 1) and those with hepatosplenomegaly with liver involvement but without ascites and jaundice (group 2). However, as liver cell dysfunction became more evident (groups 3 and 4), pharmacokinetic parameters of praziquantel such as the half-life of elimination, the half-life of absorption, the maximum concentration, the time to maximum concentration, and the area under the concentration-time curve increased proportional to the degree of hepatic insufficiency. Linear correlations were found between each of the these parameters on the one hand and hepatic function test results (total bilirubin, direct bilirubin, and serum albumin) on the other. In spite of these pharmacokinetic differences, the cure rates were 70%, 80%, 90%, and 90% in the four groups, respectively. Although the incidence of side effects was high (53%), such effects were transient and mild.

Absorption↗
PubMed1989

Atypical mycobacterial infection of the gastrointestinal tract in AIDS patients.

This paper will describe a case series of 35 AIDS patients with infection of the gastrointestinal (GI) tract with Mycobacterium avium-intracellulare (MAIC). Thirty-five homosexual men with a mean age of 35 yr and a mean duration of AIDS of 7.7 months prior to the diagnosis of MAIC were investigated to determine the extent of MAIC infection. The investigations included upper endoscopy, sigmoidoscopy, liver biopsy, bone marrow aspiration and biopsy, stool and blood cultures for MAIC, and D-xylose absorption tests. Tissue biopsy material was examined by light microscopy with the Ziehl-Neelsen stain. The duodenum was most commonly involved (30/34 men), with 65% positive on special stains and 76% positive on culture of biopsy tissue. Unusual fine white nodules, believed to be characteristic for duodenal MAIC infection, were observed in 12 men. Esophageal (two men), liver (two men), and rectal involvement (seven men) were found. In nine of 18 men (50%), the D-xylose test was abnormal. In 28 of 33 men (85%), blood cultures grew MAIC. Similarly, in 25 of 28 men (89%), bone marrow biopsies grew MAIC, and in 18 of 21 men (86%) stool samples grew MAIC. We conclude that GI tract infection with MAIC in AIDS patients is frequently associated with systemic infection with the agent. Duodenal involvement is common, and may be accompanied by a characteristic gross lesion, that of fine white nodules on the mucosa. Malabsorption, as determined by the D-xylose test, is not a universal finding, as has been reported previously.

Acquired Immunodeficiency Syndrome↗
PubMed1995

The involvement of cytosolic chymotrypsin-like, trypsin-like, and cucumsin-like activities in degradation of insulin and insulin-like growth factor I by epithelial tissues.

Using specific substrates, benzyloxycarbonyl-Gly-Gly-Leu-p-nitroanilide, benzyloxycarbonyl-Gly-Gly-Arg-2-naphthylamide and benzyloxycarbonyl-Leu-Leu-Glu-2-naphthylamide, cytosolic chymotrypsin-like, trypsin-like and cucumsin-like activities were determined, respectively, in rat epithelial tissues and differentiated human Caco-2 cells. The cytosolic fractions of rat colonic, rectal, nasal, and alveolar epithelial cells and differentiated human Caco-2 cells contained these three distinct enzyme activities. However, effects of enzyme inhibitors revealed that these three distinctive activities were not extensively involved in cytosolic or homogenate degradation of insulin and insulin-like growth factor I (IGF-I). It is concluded that proteasome-like activities may not significantly limit nonparenteral absorption of peptide and protein drugs such as insulin and IGF-I.

Adenocarcinoma↗
PubMed1973

The response of malnourished babies to cold.

1. Twelve malnourished Jamaican children, aged 4-16 months, were studied before and after treatment, to see whether malnutrition impaired their response to cold.2. When they were studied in the post-absorptive state and in a neutral thermal environment, they had a lower rate of oxygen consumption per kg body weight, a slower pulse rate, lower body temperatures, lower R.Q., and evidence of a smaller peripheral blood flow on admission to hospital than they did after recovery.3. The malnourished children failed to increase their heat production above resting levels at 25 degrees C, and their rectal temperature fell at a rate of 1 degrees C/hr in spite of a further decrease in peripheral circulation.4. When they had recovered they maintained their body temperature within the normal range on exposure to this temperature, while increasing their heat production by 20%. The thermogenesis was apparently of the non-shivering type.5. There was evidence of increased metabolic activity in the interscapular brown fat pad at 25 degrees C both on admission and before discharge. In the malnourished children this activity was not sufficient to produce a measurable increase in total oxygen consumption.6. Interscapular brown fat was examined at autopsy in thirteen malnourished and fifteen well nourished children aged 1-24 months. Lipid depletion was found in this tissue in the former but not in the latter. This may explain the impaired response of the malnourished child to cold.

Adipose Tissue, Brown↗
PubMed1990

Thermal effects of MR imaging: worst-case studies on sheep.

The objective of this study was to provide a worst-case estimate of thermal effects of MR imaging by subjecting anesthetized unshorn sheep to power deposition at specific absorption rates (SARs) well above approved standards for periods of time in excess of normal clinical imaging protocols. A control period with no RF power was followed by 20-105 min of RF power application. Afterward, there was a 20-min or longer recovery period with no RF power. Eight sheep were given whole-body RF exposure (1.5- to 4-W/kg SAR) while rectal and skin temperatures were monitored. Four sheep were subjected to 4-W/kg head scans for an average of 75 min while temperatures of the cornea, vitreous humor, head skin, jugular vein, and rectum were measured. In head scanning experiments, skin and eye temperatures increased about 1.5 degrees C. Jugular vein temperature rose a maximum of 0.4 degrees C after an average exposure of 75 min. In whole-body exposures, elevation of rectal temperature was correlated with energy input. Deep-body temperature rises in excess of 2.0 degrees C were attained for 4-W/kg whole-body exposure periods greater than 82 min. Animals exposed for 40 min to 4 W/kg in either body coil (three sheep) or head coil (two sheep) were recovered and observed to be in good health for 10 weeks; no cataracts were found. MR power deposition at SAR levels well above typical clinical imaging protocols caused body temperature to increase. For exposure periods in excess of standard clinical imaging protocols the temperature increase was insufficient to cause adverse thermal effects. Studies in healthy humans are needed to determine whether enhanced heat-loss effector mechanisms are likely to cause deep-body temperatures to plateau at an acceptable level, and to elucidate mechanisms that determine subcutaneous temperature.

Animals↗