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Leg warming minimizes core hypothermia during abdominal surgery.

The efficacy of leg skin warming in preventing hypothermia and shivering was evaluated in two separate prospective, randomized trials in patients undergoing abdominal surgery. In the first trial, 22 patients were randomized to receive no hypothermia prevention (control group) or active warming with an electric warming blanket (electric blanket group). In the second trial 33 patients were randomized to receive no hypothermia prevention (control group) or forced-air warming (Bair Hugger group) or forced-air warming with insulation of the air blanket from the environment (insulated Bair Hugger group). The core and skin temperatures were measured and changes in body heat content calculated. In the first trial, core temperature was 34.6 +/- 0.3 degrees C at the end of surgery in the control group vs 36.4 +/- 0.1 degrees C in the electric warming blanket group (P < 0.001). Shivering occurred in nine control patients and in one warmed patient (P < 0.05). In the second trial, core temperature was 35.1 +/- 0.2 degrees C at the end of surgery in the control group, 36.3 +/- 0.1 degrees C in the Bair Hugger group (P < 0.01) and 37.1 +/- 0.1 degrees C in the insulated Bair Hugger group (P < 0.01 versus control; P < 0.05 versus Bair Hugger). Shivering occurred in one patient of each warmed group and in seven of the control group (P < 0.05). Skin-surface warming limited to the legs provides sufficient heat (ranging 34 to 43 watts) to counterbalance heat losses during abdominal surgery.

Abdomen↗

Use of forced-air warming during and after outpatient arthroscopic surgery.

According to a two-phase protocol, 127 patients undergoing arthroscopic knee surgery were randomly assigned to receive intraoperative warming from a forced-air blanket (n = 69) or conventional warmed cotton blankets (n = 58). During the initial phase (Phase I), active warming was applied during the intraoperative period only, permitting double-blind assessment of postoperative events. In Phase II, warming was continued into the recovery area, which unblinded the assessment. Active warming raised skin temperature perioperatively, and reduced the decline in core temperature compared to the control group. Postoperatively, core temperature increased toward preoperative values at similar rates in both treatment groups, but was still lower in control patients after an hour in the postanesthesia care unit (PACU). Postoperative shivering occurred in 35% of all patients and was not prevented by either intraoperative or combined intraoperative and postoperative warming. However, significantly fewer actively warmed patients experienced prolonged postoperative shivering. The addition of postoperative warming appeared to provide little, if any, additional benefit. Despite the decreased duration of postoperative shivering in the actively warmed group, we were unable to demonstrate any reduction in the PACU stay.

Adult↗

Factors affecting cold acclimation and thermogenesis in man.

Three types of cold exposure are observed in man: systemic moderate cold (SM), systemic severe cold (SS), and local severe cold (LS). Contrary to rat, prolonged exposure to SM cold does not produce non-shivering thermogenesis, as it does in the rat, possibly because of lack of active brown adipose tissue. Instead there is a reduction in heat production, in shivering, and in discomfort through a process known as habituation. No adaptation was found with exposure to SS cold, since shivering and discomfort always prevail and there is indirect evidence of enhanced sympathetic response after repeated exposure to SS cold. Exposure to LS cold leads to adaptive responses in which discomfort and autonomic activity are reduced. It is suggested that LS adaptation is also related to habituation.

Acclimatization↗

The electrocardiogram in hypothermia.

OBJECTIVE: Hypothermia is known to adversely affect the electrocardiogram (ECG) in many cases. This study set out to determine the incidence of defined cardiac dysrhythmias, J waves, and conduction abnormalities in urban hypothermia. METHODS: A prospective, multicenter study was carried out to determine the incidence of defined cardiac rhythms in patients suffering from accidental urban hypothermia. The ECGs were independently analyzed by 2 of the authors and placed into 1 of 6 rhythm categories. RESULTS: Seventy-three ECGs were analyzed. Normal sinus rhythm was the most common rhythm (41%). Overall mortality was 36% (26/73). J waves occurred in 36% of survivors and 38% of non-survivors and were, therefore, not prognostic. Shivering artifact was present in 66% of survivors and 38% of nonsurvivors. Although there was no statistically significant association between J waves and survival (P = .21), the presence of shivering artifact was associated with survival in severe hypothermia (P = .047). Atrial fibrillation and junctional bradycardia were both associated with high mortality. CONCLUSIONS: This study confirms that the ECG is abnormal in the majority of patients suffering from accidental hypothermia. J waves do not appear to be independently prognostic in hypothermia. The results suggest that the inability to mount a shivering response may be associated with a poorer outcome; this finding requires further study.

Adolescent↗

Determination in vivo of newly synthesized gene expression in hamsters during phases of the hibernation cycle.

This study measured in vivo synthesis of total RNA and protein from cortex, cerebellum and midbrain/brainstem and 6 major organs from Syrian hamsters (Mesocricetus auratus) during (a) 33 h of torpor (body temperature 5-6 degrees C); (b) 90 min of the early arousal; (c) 90 min of the middle arousal; (d) 90 min in cold adapted cenothermic (CEN) hamsters of the same circannual period. Appropriate physiological parameters were used to confirm the phase of the hibernation cycle during infusion and incorporation of [3H]-uridine and [14C]-leucine. In torpor, RNA synthesis was 5-25% of CEN levels depending upon tissue. In brain and heart mRNA was not preferentially synthesized. Protein was synthesized at low, tissue specific levels during torpor. Initiation of arousal and the warming of anterior organs via non-shivering thermogenesis during the early arousal occurred without measurable synthesis of RNA or proteins. Tissue specific levels of RNA and protein synthesis occurred later after shivering thermogenesis had been recruited and was strongly influenced by thermal gradients in the body. In the middle arousal phase, protein synthesis is most active in the brain despite modest synthesis of RNA and mRNA. The majority of molecular processing required for the induction and maintenance of torpor and the arousal from torpor up until the onset of shivering thermogenesis occurs during the cenothermic period before the hamster initiates the hibernation cycle.

Adaptation, Physiological↗

Dependence of nodal sodium channel clustering on paranodal axoglial contact in the developing CNS.

Na(+) channel clustering at nodes of Ranvier in the developing rat optic nerve was analyzed to determine mechanisms of localization, including the possible requirement for glial contact in vivo. Immunofluorescence labeling for myelin-associated glycoprotein and for the protein Caspr, a component of axoglial junctions, indicated that oligodendrocytes were present, and paranodal structures formed, as early as postnatal day 7 (P7). However, the first Na(+) channel clusters were not seen until P9. Most of these were broad, and all were excluded from paranodal regions of axoglial contact. The number of detected Na(+) channel clusters increased rapidly from P12 to P22. During this same period, conduction velocity increased sharply, and Na(+) channel clusters became much more focal. To test further whether oligodendrocyte contact directly influences Na(+) channel distributions, nodes of Ranvier in the hypomyelinating mouse Shiverer were examined. This mutant has oligodendrocyte-ensheathed axons but lacks compact myelin and normal axoglial junctions. During development Na(+) channel clusters in Shiverer mice were reduced in numbers and were in aberrant locations. The subcellular location of Caspr was disrupted, and nerve conduction properties remained immature. These results indicate that in vivo, Na(+) channel clustering at nodes depends not only on the presence of oligodendrocytes but also on specific axoglial contact at paranodal junctions. In rats, ankyrin-3/G, a cytoskeletal protein implicated in Na(+) channel clustering, was detected before Na(+) channel immunoreactivity but extended into paranodes in non-nodal distributions. In Shiverer, ankyrin-3/G labeling was abnormal, suggesting that its localization also depends on axoglial contact.

Action Potentials↗

[Preoperative clonidine comedication within the scope of balanced inhalation anesthesia with sevoflurane in oral surgery procedures].

Both clonidine and sevoflurane are interesting drugs for anaesthesia in maxillo-facial surgery. The present study was performed to discover how far it is possible to combine the benefits of sevoflurane (fast modulation of depth of anaesthesia, rapid emergence and recovery) and clonidine (reduction of perioperative stress response, prophylaxis of postoperative shivering, analgetic, antiemetic and anaesthetic-saving effect) without compromising the pharmacokinetic of sevoflurane. Twenty-eight patients were included in the present double-blinded prospective study. These patients were randomly treated with an infusion of 4 micrograms kg-1 clonidine (group 1) or a placebo (group 2) preoperatively. For anaesthesia a standardized procedure with fentanyl, propofol, rocuronium, N2O/O2/sevoflurane and an antiemetic prophylaxis with DHB was performed. The depth of anaesthesia was controlled by using spectral edge frequency (target--SEF90 = 10 Hz). Perioperative stress response was assessed by noting the effects on haemodynamic parameters (MAP, heart rate), and emergence and recovery were assessed by using established standardized tests. We confirmed the anaesthetic-saving property of clonidine only for fentanyl (-20%). On the other hand, there was no difference in MAC-sevoflurane values between the groups in keeping a steady target--SEF90 (1.62 +/- 0.26 versus 1.65 +/- 0.24 vol.%). The time until emergence and recovery was not significantly different. Even the occurrence of PONV, the VAS level or the postoperative analgesic requirement did not differ in the two groups. However, the incidence of postoperative shivering was significantly higher in the placebo group. The stress response to intubation or extubation was lower in the clonidine group. The haemodynamic parameters in the clonidine group were intraoperatively always below the baseline, in some cases by more than 20%, making therapy for hypotension or bradycardia frequently necessary. Postoperatively, the majority of the patients showed similar changes in these parameters, but did not reach the 20% mark. Preoperative clonidine comedication seems to complicate the management of anaesthesia. On the other hand, it is beneficial during the early postoperative period (e.g. stability in haemodynamics, prophylaxis of shivering) without compromising emergence and recovery. Our results show that therapy with clonidine should be better placed at the end of anaesthesia.

Adult↗

Influence of thyrotrophin-releasing hormone on thermoregulatory adaptation after birth in near-term lambs delivered by caesarean section.

We investigated the hypothesis that exogenous stimulation with thyrotrophin-releasing hormone (TRH) immediately prior to umbilical cord clamping can improve thermoregulatory adaptation after birth in near-term lambs delivered by Caesarean section. Lambs received an umbilical vein injection of saline +/- TRH (8 microg) prior to cord clamping. The rate of change in colonic temperature and oxygen consumption after birth were not influenced by TRH, but TRH-treated lambs exhibited a greater incidence of shivering compared with controls over the first hour of neonatal life. Two and a half hours after birth, TRH-treated lambs possessed brown adipose tissue (BAT) with a higher thermogenic activity (i.e. GDP binding to mitochondrial protein), but their BAT had a reduced DNA content and they had less hepatic glycogen than control lambs. TRH administration had no effect on iodothyronine 5' deiodinase activity in BAT and liver, or on plasma concentrations of total triiodothyronine, thyroxine, cortisol or free fatty acids. Three TRH-treated but no control lambs, failed to establish continuous breathing, so tissues from these treated lambs together with time-matched controls were sampled 25 min after birth. These 'non-surviving' TRH-treated lambs had very high plasma catecholamine concentrations, but their lung weights were similar to controls. 'Surviving' TRH-treated lambs possessed lungs with less DNA than non-surviving TRH-treated lambs. It is concluded that umbilical vein injection of TRH prior to umbilical cord clamping increases the recruitment of both shivering and non-shivering thermogenesis after birth.

Adaptation, Physiological↗

Hypothermia with acute renal failure in a patient suffering from diabetic nephropathy and malnutrition.

We report a rare case of hypothermia with acute renal failure in a patient suffering from diabetic nephropathy. A 71-year-old male who had been receiving insulin therapy for the treatment of diabetes mellitus complicated with advanced diabetic nephropathy since 1998 was malnourished with an extremely decreased muscle mass. Without any prolonged exposure to excessively low external temperatures or hypothyroidism, pituitary insufficiency, adrenal insufficiency, sepsis, hypoglycemia, and diabetic ketoacidosis, acute hypothermia appeared together with an aggravation of diabetic nephropathy. His skin temperature fell to below measurable levels and his rectal temperature fell to 30.0 degrees C. His consciousness was drowsy and the hypothermia was not accompanied by shivering. Skeletal muscle is known to play an important role as a center of heat production and shivering thermogenesis in skeletal muscle mainly operates on acute cold stress. Therefore, in this case, hypothermia may have occurred because the shivering thermogenesis could not fully act on the acute cold stress due to the dramatically reduced muscle mass. We should always keep in mind that older, malnourished diabetic patients can easily suffer from impairments of the thermoregulatory system.

Acute Kidney Injury↗

Thermoregulation in winter swimmers and physiological significance of human catecholamine thermogenesis.

Thermoregulation in control subjects and cold-adapted winter swimmers was examined during 1 h of cold water immersion (13 C). It was found that the thermoregulatory functions of winter swimmers differ from those of non-cold-adapted subjects. As evident from the relationship between rectal temperature and the magnitude of cold thermogenesis, in controls a significant part of cold thermogenesis during the early phase of cooling was induced by changes in peripheral temperature input, while in the late phase of cooling it was the central temperature input which was mainly engaged in induction of cold thermogenesis. In winter swimmers the magnitude of cold thermogenesis was solely related to changes in rectal temperature, indicating the predominance of the central temperature input in activation of heat production mechanisms. The thermoregulatory threshold for induction of cold thermogenesis was lowered (by 0.34 C), but the apparent hypothalamic thermosensitivity was the same as in non-cold-adapted subjects. These differences are indicative of adaptation of thermoregulatory control centres. Additionally, the activity of thermoregulatory effectors was also changed. Shivering was induced later during cooling (after 40 min) in winter swimmers than in controls, which suggests an important participation of non-shivering thermogenesis in the early thermogenic response. Winter swimmers also showed bradycardia and a greater reduction in plasma volume during cooling. The data indirectly indicate restriction of heat loss from the body. Only a non-significant increase in quantity of subcutaneous fat was observed in winter swimmers. Thus, winter swimmers were able to survive a significantly greater temperature gradient between body and environment than non-cold-adapted subjects by modifying the sensory functions of hypothalamic thermoregulatory centres to lower heat loss and produce less heat during cold exposure. Additionally, the capacity of the total cold thermogenesis due to potentiation of non-shivering heat production was also increased. Heat produced due to thermogenic action of adrenaline may represent more than a quarter of the total cold thermogenesis. In conclusion, the data suggest that winter swimmers exhibit metabolic, hypothermic and insulative types of cold adaptation.

Adaptation, Physiological↗

Primordial hematopoietic stem cells generate microglia but not myelin-forming cells in a neural environment.

Finding ways to enhance remyelination is a major challenge in treating demyelinating diseases. Recent studies have suggested that circulating bone marrow cells can home in brain and transdifferentiate into neural cells. To ask whether hematopoietic precursors can form myelinating cells, we investigated the neuropoietic potential of embryonic precursors sorted from the mouse aorta-gonads-mesonephros (AGM) region. This cell fraction is capable of long-term hematopoietic reconstitution and generates colonies containing multipotential precursors and lymphoid or erythro-myeloid progenies. When cultured in hematopoietic growth conditions, a fraction of CD45-positive AGM cells coexpress neural markers such as nestin, the polysialylated form of neural cell adhesion molecule, the betaIII tubulin isoform, and glial fibrillary acidic protein. However, when hematopoietic precursors containing green fluorescent protein were cocultured with embryonic striatal precursors into neurospheres, they maintained their hematopoietic phenotype without undergoing differentiation into neurons, astrocytes, or oligodendrocytes. After intraventricular grafting, hematopoietic precursors integrated into the brain of wild-type or hypomyelinated newborn shiverer mice and gave rise to microglia but not neurons or glia. In contrast, when wild-type embryonic striatal neurospheres were grafted in shiverer, they formed numerous myelin internode patches. Even when neural and hematopoietic precursors were grafted together into shiverer mice, only neural precursors generated myelin-forming cells and synthesized myelin. Thus, embryonic neurospheres have myelin repair properties not shown by embryonic hematopoietic precursors. This suggests that the use of multipotential neural precursors to generate myelin-forming cells remains one of the most promising avenues toward remyelination therapies.

Animals↗

[Obstetrical peridural anesthesia with bupivacaine and buprenorphine. A randomized double-blind study in comparison with untreated controls].

Epidural anaesthesia with local anaesthetics has become a standard method of pain relief during labour. In recent years, spinal opiates, alone and in combination with local anaesthetics, have also been tried with varying degrees of success. Buprenorphine, a potent lipophilic opiate with long duration of action, has been used in several trials for caesarean section [3, 4, 6], but not yet in spontaneous labour. The aim of the present investigation was to evaluate epidural anaesthesia with bupivacaine alone and with bupivacaine+buprenorphine in comparison with no anaesthetic treatment in control parturients. METHODS. A total of 80 healthy women during labour at full term (age 18-38 years, weight 54-107 kg) were studied to evaluate the influence of 0.3 mg buprenorphine (group BB) vs placebo (group B) added to an initial dose of 15 ml plain bupivacaine 0.33% for lumbar catheter epidural anaesthesia. Plain bupivacaine 0.25% (10 ml) without any opiate admixture was used for reinjections. The control group was made up of 48 untreated parturients. After every injection, blood pressure, heart rate and respiratory rate were measured repeatedly, as were time intervals between injections, extent of blockade, duration of labour, actual and retrospective visual analogue pain score, and side effects such as pruritus, shivering or nausea and emesis. Maternal capillary blood gases were analysed three times during labour, and Apgar scores and venous and arterial umbilical blood gas analyses were obtained immediately after delivery. RESULTS. Admixture of buprenorphine 0.3 mg significantly increased the time interval between the first and second epidural doses (B: 162 +/- 47 vs BB: 224 +/- 64 min; mean, SD; Table 2) and significantly reduced the incidence of shivering (Table 9). The incidence of instrumental delivery was comparable in all groups (bupivacaine 32.5%, bupivacaine+buprenorphine 27.5%, control 21%; n.s.). No clinically relevant differences were observed between the epidural patients in onset and duration of the block (Fig. 1), analgesic efficacy (Fig. 2), duration of spontaneous labour (BB: 8.6 +/- 3.1 h, B: 8.5 +/- 2.9 h; n.s.) and vital functions of mothers and newborns. Although some statistically significant differences between the three groups were found in some parameters of the blood gas analyses (Table 7), the clinical condition of the newborns was always acceptable; Apgar scores were not significantly different. DISCUSSION AND CONCLUSIONS. The addition of buprenorphine to bupivacaine resulted in some advantages to the mother (reduced incidence of shivering) and the anaesthetist (time lapse before first reinjection was necessary) without jeopardizing the situation of the baby. Compared with untreated control parturients, retrospective pain scores during epidural anaesthesia with bupivacaine (with or without buprenorphine) were significantly lower. No clinically relevant disadvantages of epidural anaesthesia were observed. More studies are required to evaluate whether buprenorphine admixture allows a dose reduction of bupivacaine and could then claim clearer advantages than were found in the present investigation.

Adult↗

[O2 uptake in the recovery period. The effect of the anesthetic procedure and the postoperative administration of pethidine].

UNLABELLED: General anesthesia leads to a marked reduction in oxygen uptake (VO2), but during the recovery period O2 consumption can increase dramatically. A controversial discussion has continued in the literature concerning the role of different types of anesthesia with regard to metabolic changes. The aim of this comparative study was to evaluate the effects of two different techniques for general anesthesia and of postoperative meperidine on VO2, especially in the postanesthetic recovery period. METHODS: Twelve patients (K1: ASA class I-II, age: 39.9 +/- 16.1 years, height: 176 +/- 10.1 cm, weight: 76 +/- 12.8 kg) scheduled for urological lower abdominal surgery were given isoflurane-N2O-O2 (1.3 MAC); another group of 12 patients (K2: ASA class I-II, 35.9 +/- 14.5 years, 181.8 +/- 11.4 cm, 77.3 +/- 8.4 kg) received total intravenous anesthesia (TIVA) with propofol and alfentanil (ED95). Both groups were studied under steady-state conditions. Duration of anesthesia was 124.2 +/- 27.5 min (K2) versus 139.2 +/- 35.5 min (K1). VO2 was measured by an indirect calorimetric device (MMC Horizon, STPD). RESULTS: Preanesthetic values of VO2 were in the predicted range for basal metabolism. Steady-state general anesthesia led to approximately 30% reduction in VO2 (K1: 121-225 ml min, K2: 107-230 ml/min) compared to preanesthetic values (P less than 0.05). Both groups showed an increase in VO2 during the recovery period. When compared to the preanesthetic measurements, only K1 showed a statistically significant change. Shivering was observed during the recovery period in 8 patients in K1 (max VO2: 639 ml min) and 2 in K2 (max VO2: 584 ml min (P less than 0.05). Meperidine (25 mg i.v.) given to 5 patients from K1 because of postanesthetic shivering decreased VO2 significantly to the range of VO2 measured in K2. CONCLUSION: Oxygen consumption during general anesthesia was not defined by the type of anesthetic administered. During the recovery period however, VO2 depended on the type of anesthetic, as muscular hyperactivity was prominent in the isoflurane group. Meperidine could suppress visible shivering and reduce postoperative VO2 to the levels seen after TIVA.

Adult↗

[Hemodynamic and gasometric modifications during the anesthesia recovery period in patients undergoing ventilation after surgery of the abdominal aorta].

This study was carried out on 12 patients (mean age 61) in order to assess the oxygen consumption (VO2) in the post-operative stage of an elective surgical procedure (replacement of the abdominal aorta). Anesthesia was a combination of thiopentone, pancuronium bromide and high doses of droperidol and fentanyl. Patients were kept intubated and ventilated in the post-operative period. VO2 and other related metabolic parameters as well as hemodynamic parameters were measured every 45 minutes over a period of 5 hours. A VO2 increase (127%) related to the increase in body temperature was noted. Mean VO2 for all patients during the whole period was 170 +/- 13 ml.min-1.m-2 (range: 51-411 ml.min-1.m-2). Mean value of maximal VO2 was 240 +/- 21 ml.min-1.m-2 (range: 1471-411 ml.min-1.m-2). Large dose of droperidol are shown to limit VO2 increase. In patients with shivering, the maximal value of VO2 was found during shivering. The amount of droperidol administered during anesthesia was greater in patients without shivering. VO2 increase was due to a rise in tissular O2 extraction. Cardiac index was insufficiently increased (+ 9.4%) and a certain extent of myocardial inadaptability was suspected in relation with: high blood pressure, hypovolaemia and/or myocardial effect of anesthesia agents.

Anesthesia Recovery Period↗

The thermogenic role of adipose tissue in the dog.

Brown adipose tissue was clearly present in neonatal dogs. In the adult the tissue was superseded by a tissue with the gross characteristics of white adipose. However despite their appearance adult adipose tissue depots may contribute to non-shivering thermogenesis. Regional blood flow measurements using injected radioactive microspheres indicated large increases in blood flow to adipose depots during infusion of noradrenaline. Coupled with blood flow estimations, measurement of arteriovenous differences in dissolved oxygen across the bladder fat depot demonstrated a quantitative increase in oxygen extraction by the depot during noradrenaline infusion. Acute activation of non-shivering thermogenesis in the dog was not associated with increased mitochondrial GDP-binding in adipose tissue. However chronic treatment with a beta-stimulant (LY79730) which increased capacity for non-shivering thermogenesis was associated with increased mitochondrial GDP-binding and cytochrome oxidase activity in peri-renal adipose tissue.

2-Hydroxyphenethylamine↗

Rewarming and cardiac surgery: a review.

Patients undergoing cardiac surgery are mildly hypothermic by the completion of the surgical procedure. They need to return to a normothermic state if enzymatic functions are to proceed in their normal manner. The body can produce heat by elevating metabolic rate or by activating the shivering mechanism. Metabolic rate peaks shortly after separation of the patient from cardiopulmonary bypass, and therefore contributes to heat production. Because of the effects of neuromuscular blockage administered both during and after surgery; these patients may be unable to generate heat by shivering, and shivering is usually undesirable. This eliminates the major heat production mechanism available to the body. Therefore, heat must be transferred down its gradient by means of convection and conduction. External and internal methods accomplish these goals. External methods, which minimize additional heat loss, include the use of warming lights, elevation of room temperature, and the use of blankets. Internal methods, which transfer heat by convection, may be used to help actively reverse hypothermia. Such techniques include warmed inhalation gases and intravenous fluids, warmed nasogastric lavage fluid, and warmed peritoneal dialysis fluid for patients with end-stage renal failure with severe electrolyte disorders after surgery.

Body Temperature Regulation↗

Hyperiodothyroninaemia of neonates, its significance for thermogenesis.

Danowski et al. (1951) were probably the first who showed an increase of PBI in infants shortly after birth. Later a number of investigators presented further evidence on the increased thyroid gland function in newborns. This condition named "neonatal thyroid hyperactivity" [Fisher and Oddie, 1964] was described also in animals. The available data indicate that all the newborn mammals till now studied, independently of the maturation stage of development they reach at birth, display some features of thyroid hyperactivity, but in some it does not lead to hyperiodothyroninaemia. Interspecies differences coincide well with significance of the thyroid hormones for neonatal thermogenesis. There are few sequential studies of the three principal iodothyronines: T4, T3 and rT3 available at present. The most comprehensive data concern infants, newborn lambs and pigs. Immediately after birth, there is a sudden rise in serum thyroid hormone concentrations, with some species differences related to the degree of the increase and to the iodothyronines involved. The course of the postnatal hyperiodothyroninaemia is dependent on the maturation level reached at birth, food intake, and cooling relative to extrauterine environment. At least five main factors contribute to the immediate postnatal hyperiodothyroninaemia: 1) abrupt depletion of the preformed fetal hormonal iodine stores; 2) preferential T3 secretion; 3) increase in the T4 to T3 monodeiodination in the peripheral tissues; 4) a release of thyroid hormone content from peripheral reservoirs to plasma, and 5) action of other hormone(s) concomitantly released at birth. From the point of view of the thermal adaptability, the newborn mammals fall into two distinct groups: first, in which immediately after birth the metabolic rate decreases, and second, in which the metabolic rate increases, after cooling. Our understanding of the role and significance of hormonal factors involved in mechanisms of the postnatal thermogenesis is incomplete. However, some similarities in adaptation to cold in adults and in newborns seem to be relevant. Cold adaptation is accomplished by development of nonshivering thermogenesis (NST) depending on NA. The presence of brown adipose tissue (BAT) is essential for NA thermogenic action. According to the common opinion, based on data from laboratory animals and human baby, non-shivering thermogenesis, but not shivering, predominates in newborns. However, data from domestic animals indicate that shivering thermogenesis may be of comparable or greater thermogenic capacity than NST at birth. Besides, there are some newborns which have little or no BAT and associated NST.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

[Indication for operation in acute kidney obstruction caused by urinary calculi].

We like to discuss the comment of our clinic: In case of an acute stone-conditioned renal blockage complicated by fever we immediately perform a decompression by means of elevation of the ureter catheter and the antibiotic therapy. A shivering attack accompanied by fever we regard as a threatening sign of pyelonephritis apostematosa and possibly after the first or second shivering attack we perform an opening. Apart from emphasizing the importance of the shivering attack we still might refer to the fact that for the establishment of the therapy of choice the complex evaluation of the clinical picture is necessary.

Anti-Bacterial Agents↗