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PubMed1988

Computed tomography of the brain, chest, and abdomen in the preoperative assessment of non-small cell lung cancer.

The benefit to be gained from carrying out computed tomography of brain and abdomen in addition to the chest has been evaluated retrospectively in 114 consecutive patients with non-small cell lung cancer who, on the basis of history, clinical examination, chest radiography, and bronchoscopy had been considered potentially operable. Computed tomography of the chest showed potentially inoperable tumour in 37 patients, of whom 25 had tumour confined to the chest. Three patients were shown to have malignant disease within the mediastinum and abdomen; five within the mediastinum and brain; and four within the mediastinum, abdomen, and brain. Computed tomography of the abdomen disclosed deposits in nine patients, but in only two were the abnormalities restricted to the abdomen. Computed tomography of the brain showed metastases in 10 patients, of whom only one had metastatic disease confined to the brain. Thus three patients had isolated deposits in the abdomen and brain. In 12 patients the identification of metastases in the abdomen and brain removed the need for mediastinoscopy. Preoperative computed tomography of the abdomen and brain detected occult metastases in 15 patients (13%) in this study. In three patients the extrathoracic abnormality proved the only contraindication to surgery, but in the other 12 it provided valuable corroborative evidence of incurability and facilitated the assessment of the mediastinal abnormality.

Abdominal Neoplasms↗
PubMed1998

Acute abdomen in pregnancy.

OBJECTIVE: To calculate the frequency of acute abdomen in pregnancy due to non-obstetric causes in a Saudi population, to discuss the etiology of the high incidence, to discuss how pregnancy altered the symptomatology of acute abdomen and to evaluate the result of early surgical intervention and use of tocolytics on maternal and fetal health. DESIGN: Retrospective analytic study of all cases of acute abdomen in pregnancy admitted between 1/1/1991 and 31/12/1993 to evaluate the result of early surgical intervention and use of tocolytics. SETTING: The surgical wards of Asir Central Hospital, Abha, Saudi Arabia. SUBJECTS: Sixty pregnant Saudi females who were admitted because of acute abdomen due to non-obstetric causes. RESULTS: The frequency of acute abdomen in pregnancy due to non-obstetric causes in this population is 0.39% which is high in comparison to other studies and the etiology is multifactorial. Resemblance of early acute abdomen symptoms like nausea, vomiting to those of normal pregnancy and the anatomical displacement of abdominal organs by the pregnant uterus greatly masked the clinical picture and enhanced surgical delay awaiting definitive criteria for surgical intervention. This delay significantly increased maternal morbidity (P < 0.05) and resulted in a poor fetal outcome. Those who had early surgical intervention had a better perinatal outcome (P < 0.001) and decreased maternal morbidity (P < 0.05). Although tocolytics were used, they proved to be ineffective, altered the maternal clinical picture and had fetal side-effects. CONCLUSION: There is a higher incidence of acute abdomen in pregnancy and although pregnancy blunted the clinical picture, early surgical intervention resulted in a better perinatal outcome and decreased maternal morbidity. Tocolytics had their side effects and did not improve the fetal outcome.

Abdomen, Acute↗
PubMed1998

Spatiotemporal measurement of free radical elimination in the abdomen using an in vivo ESR-CT imaging system.

Electron spin resonance (ESR) imaging can visualize the distribution of free radicals in living systems according to their concentrations. However, the application of ESR imaging to living animals has not been well established. Using a rapid field scan L-band ESR imaging system, we have successfully obtained two-dimensional ESR projection (xz-plane projection) and three-dimensional ESR-CT (trans-axial section along the y-axis) images of the abdomen of living mice after an injection of 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (carbamoyl-PROXYL) into the tail vein. The in vivo two-dimensional ESR projection imaging clearly visualized the carbamoyl-PROXYL distribution and the rapid decay process in the abdomen. Because among the viscera, the liver is most abundantly associated with a blood volume, the outline of the image can be composed mainly of this organ. We therefore attempted to find whether there will be a difference in spatiotemporal dynamics of carbamoyl-PROXYL in the abdomens between the control and the mice with liver damage by two-dimensional ESR projection. In the control mice, carbamoyl-PROXYL was almost completely eliminated from the abdomen within 5 minutes after administration. On the other hand, in mice with carbon tetrachloride-damaged livers, the decay of carbamoyl-PROXYL was markedly prolonged. Even at 5 min after administration, carbamoyl-PROXYL remained clearly visible in the abdomen. In vivo three-dimensional ESR-CT imaging showed an even distribution of carbamoyl-PROXYL throughout the whole liver, which corresponded well with the images of trans-axial sections of the murine abdomen. We have succeeded in displaying two-dimensional ESR projection and three-dimensional ESR-CT images of carbamoyl-PROXYL distribution and clearance in the abdomen of a living animal. The ESR-CT imaging technique is considered to be a powerful new tool for noninvasive investigations of the in vivo spatiotemporal dynamics of free radical distribution and elimination in the organs.

Abdomen↗
PubMed1995

Mechanical factors influencing the incidence of burst abdomen.

OBJECTIVE: To compare laparotomy closure with interrupted polyglactin 910 (Vicryl) and continuous polydioxanone (PDS II), and assess the mechanical and other factors that influenced the incidence of burst abdomen. DESIGN: Retrospective study. SETTING: University hospital, The Netherlands. SUBJECTS: A random sample of 346 patients who did not burst their abdomens, taken from the total of 3768 patients who underwent primary midline laparotomy from 1986-1990, together with the 45 (1%) from the total series who did burst their abdomens. MAIN OUTCOME MEASURES: Incidence of burst abdomen, and the association with mechanical and others risk factors. RESULTS: There were no differences in the incidence of burst abdomen between those sutured with interrupted polyglactin 910 and those sutured with continuous polydioxanone (p = 0.12). Layered closure resulted in significantly more burst abdomens than any other method of closure (p < 0.001 in each case). Postoperative wound infection (14/43, 33%, compared with 33/343 10%) and pulmonary complications (25/43, 58%, compared with 44/344, 13%) were also significantly associated with the development of burst abdomens (p < 0.001). CONCLUSIONS: A continuous, monofilament, absorbable suture should be used to close a laparotomy incision. Elastic suture material, loop sutures, an the continuous figure-of-eight technique should be investigated.

Abdomen↗
PubMed1980

Synthesis of a posterior indicator protein in normal embryos and double abdomens of Smittia sp. (Chironomidae, Diptera).

In embryos of the chironomid midge Smittia, synthesis of a posterior indicator protein designated PI1 (Mr approximately 50,000; pI approximately 5.5) forecasts development of an abdomen as opposed to head and thorax. The protein is synthesized several hours before germ anlage formation. In normal embryos at early blastoderm stages, synthesis of PI1 is restricted to posterior embryonic fragments but not to pole cells. In "double-abdomen" embryos, a mirror-image duplication of the abdomen is formed by cells that would otherwise develop into head and thorax. Embryos were programmed for double-abdomen development by UV irradiation of the anterior pole, and half of them were reprogrammed for normal development by subsequent exposure to visible light (photoreversal). Correspondingly, PI1 was synthesized in anterior fragments of UV-irradiated embryos but not after photoreversal. In a control experiment, UV irradiation of the posterior pole caused neither double-abdomen formation nor PI1 synthesis in anterior fragments. The identity of PI1 formed in anterior fragments of prospective double abdomens with the protein found in posterior fragments was revealed by two-dimensional gel electrophoresis and limited proteolysis. Suppression of PI1 synthesis in anterior fragments of normal embryos is ascribed to the activity of cytoplasmic ribonucleoprotein particles thought to act as anterior determinants.

Abdomen↗
PubMed2003

Immediate closure of the open abdomen with bilateral bipedicle anterior abdominal skin flaps and subsequent retrorectus prosthetic mesh repair of the late giant ventral hernias.

BACKGROUND: Management of the open abdomen in trauma and nontrauma patients is difficult, and some areas of controversy remain. Gastrointestinal fistulas are serious complications that are associated with significant mortality. We present our method for management of patients with open abdomen and also present a logical technique of subsequent repair of the late giant ventral hernias that uniformly occur in these patients. METHODS: From January 1992 to December 2001, nine patients with open abdomen underwent successful immediate closure with bilateral bipedicle anterior abdominal skin flaps. The major points of this technique of abdominal closure are coverage of abdominal viscera with absorbable mesh and mobilization of the skin and subcutaneous tissue on both sides of the abdominal wound to cover the absorbable mesh. All patients had uneventful recovery and also had subsequent late giant ventral hernias. Repair of the late giant ventral hernias was performed several months later by inserting a large sheet of nonabsorbable mesh under the rectus abdominis muscles that form the neck of the ventral hernia bilaterally. This technique of ventral hernia repair is also called retrorectus prosthetic mesh repair. RESULTS: Five men and four women were entered into the study. The age ranged from 22 to 53 years (median, 35 years). Seven patients suffered from blunt and penetrating trauma and two patients suffered from nontrauma causes. All patients with immediate closure of the open abdomen had uneventful recovery. Late giant ventral hernias (diameter, > 10 cm) occurred in all patients. The time from closure of the open abdomen to subsequent repair of the giant ventral hernias ranged from 7 to 48 months (median, 14 months). Follow-up after hernia repair ranged from 1 to 72 months (median, 9 months), and we have seen no evidence of recurrence. CONCLUSION: Immediate closure of the open abdomen with bilateral bipedicle anterior abdominal skin flaps is an effective technique for dealing with such potentially complicated problems. Management of late giant ventral hernias with retrorectus prosthetic mesh repair is theoretically reasonable and, so far, no recurrence has been observed in our patients.

Abdomen↗
PubMed2002

Clinical evaluation of digital radiography based on a large-area cesium iodide-amorphous silicon flat-panel detector compared with screen-film radiography for skeletal system and abdomen.

The aim of this clinical study was to compare the image quality of digital radiography using the new digital Bucky system based on a flat-panel detector with that of a conventional screen-film system for the skeletal structure and the abdomen. Fifty patients were examined using digital radiography with a flat-panel detector and screen-film systems, 25 for the skeletal structures and 25 for the abdomen. Six radiologists judged each paired image acquired under the same exposure parameters concerning three observation items for the bone and six items for the abdomen. Digital radiographic images for the bone were evaluated to be similar to screen-film images at the mean of 42.2%, to be superior at 50.2%, and to be inferior at 7.6%. Digital radiographic images for the abdomen were judged to be similar to screen-film images at the mean of 43.4%, superior at 52.4%, and inferior at 4.2%; thus, digital radiographic images were estimated to be either similar as or superior to screen-film images at over 92% for the bone and abdomen. On the statistical analysis, digital radiographic images were also judged to be preferred significantly in the most items for the bone and abdomen. In conclusion, the image quality of digital radiography with a flat-panel detector was superior to that of a screen-film system under the same exposure parameters, suggesting that dose reduction is possible with digital radiography.

Adult↗
PubMed1995

The head-to-abdomen circumference ratio: a reappraisal.

Our objective was to assess the clinical significance of the sonographically derived head-to-abdomen circumference ratio in small-for-gestational-age (SGA) fetuses. The head-to-abdomen ratio was determined in 134 singleton SGA fetuses without ultrasound evidence of malformations at 26-40 weeks' gestation. Data were collected regarding antenatal surveillance, umbilical artery Doppler velocimetry and neonatal outcome. In SGA fetuses, the head-to-abdomen ratio, adjusted for gestational age, had a normal frequency distribution, positively skewed with regard to fetuses with normal birth weight. An elevated head-to-abdomen ratio was found in 56 SGA fetuses (42%), and was associated with increased perinatal mortality (odds ratio 3.27; 95% confidence internal 1.04-9.34), lower birth weight (1533 +/- 635 g vs. 2022 +/- 655 g, p < 0.0001) and lower gestational age at delivery (34 +/- 3.6 weeks vs. 36.3 +/- 3.6 weeks, p < 0.005). However, logistic regression revealed that the most powerful antenatal determinants of pregnancy outcome were Doppler velocimetry of the umbilical artery, followed by biophysical profile, while no independent correlation was found with the head-to-abdomen ratio. The existence of two distinct categories of SGA fetuses, 'symmetric' and 'asymmetric', remains uncertain. An elevated head-to-abdomen ratio is an adverse risk factor for pregnancy outcome. However, this parameter has no clearcut clinical value when umbilical artery Doppler velocimetry and biophysical antenatal testing are available.

Birth Weight↗
PubMed1996

[Calculated organ doses and effective dosage for computerized tomography examination of the thorax and abdomen: are these doses realistic?].

PURPOSE: To analyse how far dose calculations for the CT examination of the thorax and abdomen can lead to faulty estimations of organ doses and effective dose due to differences in the topographic anatomy between mathematical phantom and man. METHODS: For the CT examination of the thorax, upper abdomen, pancreas, pelvis and the entire abdomen, organ doses were calculated with conversion factors, first with regard to the topographic relation within the phantom, then with additional regard to the real anatomy of the man. RESULTS: In the phantom, the abdomen lies outside the scan volume in case of CT-examination of the thorax and the whole intestine outside the scan volume in case of CT-examination of the upper abdomen and the pancreas, whereas the entire intestine is directly exposed in case of CT-examination of the pelvis. Dependent on whether dose calculations take real anatomy into account, doses of special organs can differ by a factor greater than 15. The calculated effective doses differ by a factor less than 1.5. CONCLUSIONS: Calculations of organ doses for the CT examination of the thorax and abdomen can lead to considerable errors due to different topographic relations between phantom and man. In contrast the calculated effective dose is realistic. Hence, dose calculations with the help of mathematical phantom is an efficient method to estimate the total radiogenic risk.

Female↗
PubMed1998

[Radiation exposure during CT examination of thorax and abdomen. Comparison of sequential, spiral and electron beam computed tomography].

Comparison of radiation exposure applied by different types of CT scanners for the investigation of the chest and abdomen. Determination of radiation exposure applied by multi-phase spiral CT. Estimation of the dose in air in the system axis of the scanner, the CT dose index (CTDI) and the effective dose for electron beam tomography (EBT) and two conventional CT scanners (sequence, SEQ; spiral, SCT). For EBT, dose in system axis for investigation of the abdomen was above 50 mGy. Effective dose for investigation of the chest and abdomen was higher with EBT (11 and 26 mSv, respectively) than with conventional CT (SEQ, 4 and 20 mSv; SCT, 2 and 7 mSv). The effective dose for a biphasic investigation (liver 5 mSv, kidney 4 mSv) was below, for a triphasic investigation (liver 7 mSv) above the effective dose of the investigation of the abdomen (6 mSv). Investigation of the abdomen with the EBT should only be performed for certain indications. With spiral CT, effective dose is much lower than with EBT.

Abdomen↗
PubMed1995

Massage-like stroking of the abdomen lowers blood pressure in anesthetized rats: influence of oxytocin.

The aim of this study was to determine how massage-like stroking of the abdomen in rats influences arterial blood pressure. The participation of oxytocinergic mechanisms in this effect was also investigated. The ventral and/or lateral sides of the abdomen were stroked at a speed of 20 cm/s with a frequency of 0.017-0.67 Hz in pentobarbital anesthetized, artificially ventilated rats. Arterial blood pressure was recorded with a pressure transducer via a catheter in the carotid artery. Stroking of the ventral, or both ventral and lateral sides of the abdomen for 1 min with a frequency of 0.67 Hz caused a marked decrease in arterial blood pressure (approx. 50 mmHg). After cessation of the stimulation blood pressure returned to the control level within 1 min. The maximum decrease in blood pressure was achieved at frequencies of 0.083 Hz or more. Stroking only the lateral sides of the abdomen elicited a significantly smaller decrease in blood pressure (approx. 30 mmHg decrease) than stroking the ventral side. The decrease in blood pressure caused by stroking was not altered by s.c. administration of an oxytocin antagonist (1-deamino-2-D-Tyr-(Oet)-4-Thr-8-Orn-oxytocin, 1 mg/kg) directed against the uterine receptor. In contrast, the administration of 0.1 mg/kg of oxytocin diminished the effect, which was antagonized by a simultaneous injection of the oxytocin antagonist. These results indicate that the massage-like stroking of the abdomen decreases blood pressure in anesthetized rats. This effect does not involve intrinsic oxytocinergic transmission. However, since exogenously applied oxytocin was found to diminish the effect of stroking, oxytocin may exert an inhibitory modulatory effect on this reflex arc.

Abdomen↗
PubMed1993

Salvage whole abdomen radiation therapy: its role in ovarian cancer.

PURPOSE: In spite of high initial response rates, many patients with epithelial ovarian carcinoma eventually fail their primary treatment. Further treatment with second-line regimens has been ineffective in producing durable responses. Thus, whole abdomen radiation therapy was evaluated as a salvage therapeutic modality as to its feasibility, efficacy, and toxicity. METHODS AND MATERIALS: Between June 1983 and June 1990, 44 patients who failed one or more chemotherapeutic regimens were treated with whole abdomen radiation therapy. Forty patients had epithelial carcinoma of the ovary and the remaining had primary adenocarcinoma of the peritoneal cavity. Radiation was delivered with an open-field technique and 2500 cGy were planned to the whole abdomen, with a boost when indicated. Prior to radiation, the amount of residual disease after debulking was noted to be microscopic in one-half of the patients and macroscopic in the other half. Pelvis alone was the site of residual disease in 14 patients, and upper abdominal involvement was found in 30. RESULTS: Five patients (11%) were unable to complete the planned therapy secondary to acute toxicity. The 4-year actuarial survival and recurrence-free survival rates for the entire group were 23% and 22%, respectively. The survival and recurrence-free survival rates for the group with microscopic residual disease at 37% and 42% were significantly better than those for the patients with macroscopic residual disease at 9% and 5% (p < 0.005; p < 0.001) at 4 years, respectively. Patients with disease limited to pelvis only had a recurrence-free survival of 56% compared to 0% when the upper abdomen was involved (p < 0.005). The abdomino-pelvic cavity was the first site of recurrence in 28 of 31 patients in whom the site of recurrence could be determined. Eight patients (18%) experienced bowel complications, of whom five needed surgical intervention. CONCLUSIONS: Whole abdomen radiation therapy with a pelvic boost is feasible with acceptable acute and late toxicity. It is effective in patients with minimal residual disease.

Abdomen↗
PubMedDate not supplied

CT appearance of acute abdomen as initial presentation in lymphoma of the large and small bowel.

Computed tomography (CT) is playing an increasingly greater role as the initial diagnostic imaging modality for acute abdomen. Abdominal pain is the most common presenting complaint for intestinal lymphoma, and acute abdomen is a not infrequent admitting complaint. We present the CT findings of five patients with intestinal lymphoma whose initial complaint was acute abdomen. Of these five patients, four had an identifiable mass that was located in the right lower quadrant, with the fifth patient having no identifiable mass on CT. The average mass size was 7.8 cm. Three of the patients showed involvement of the colon only, and two showed involvement of the small bowel only, with acute abdomen in only one of the patients with small-bowel involvement being due to direct extension from mesenteric lymph nodes. Pneumoperitoneum and free intraperitoneal fluid were seen in two patients. It is important, therefore, that the radiologist be aware that one of the causes of acute abdomen with primary bowel involvement is lymphoma, which can simulate appendicitis or diverticulitis in its presentation clinically and by physical examination.

Abdomen, Acute↗
PubMed1976

Dynamics of the chest wall during speech production: function of the thorax, rib cage, diaphragm, and abdomen.

Anteroposterior diameters of the rib cage and abdomen and esophageal and gastric pressures were measured in normal subjects in upright and supine body positions during respiratory maneuvers and utterance tasks. Data were charted in relative motion diagrams and various motion-pressure diagrams which enabled graphic solution for muscular pressures exerted by the chest wall and individually by the thorax, rib cage, diaphragm, and abdomen during utterances. Behaviors of the chest wall and its parts were found to depend upon lung volume, utterance loudness, body position, and utterance task. For utterances encompassing most of the vital capacity, chest wall effort was at first net inspiratory and later net expiratory. The former was governed predominately by the rib cage and the abdomen in the upright body position and by the diaphragm in the supine position. For conversational speech, chest wall effort was continuously expiratory, control being vested in the rib cage and the abdomen in the upright body position and typically in the rib cage alone in the supine position. Mechanisms operating during the utterances are discussed, particularly those involved with conversational speech production. We conclude that the abdomen occupies an especially important role in running conversational speech in that it mechanically tunes the diaphragm to increase the latter's inspiratory efficiency and thus enables man to minimally interrupt his ongoing speech for needed inspiratory pauses. We also discuss the relevance of our findings to clinical endeavors.

Abdomen↗
PubMed2001

Outcome of the acute abdomen in patients with previous spinal cord injury.

BACKGROUND: Patients with spinal cord injury (SCI) have always posed difficulties for the diagnosis of an acute abdomen. The aim of the present study was to define this problem retrospectively at Princess Alexandra Hospital and to assess the results of treatment for these patients. METHODS: A retrospective review was conducted of 133 SCI patients admitted with an acute abdomen in the 16 years prior to this analysis at the Spinal Injuries Unit (SIU) of Princess Alexandra Hospital. There were 21 patients who conformed to the study criteria. All the patients had sustained traumatic SCI at or above the level of T11, more than 1 month prior to admission. RESULTS: There were 13 male and eight female patients. The time lapse between SCI and the onset of an acute abdomen ranged from 1.5 months to 27 years. The age range was 26-79 years. The majority of patients had C6 injuries (six patients). There were 18 patients with injury levels above T6 and three patients with injuries below this level. The time taken to diagnose the cause of the acute abdomen ranged between I day and 3 months. Investigations were found to be useful in making the diagnoses in 61.9% of cases. There were 14 patients who had surgical interventions. Five patients had surgical complications and there were two deaths in the study. The length of follow up was 1-132 months. The mortality in the study was 9.5%. CONCLUSION: An aggressive approach to the diagnosis and treatment of the acute abdomen in SCI patients with suspicious symptoms is recommended. A high index of suspicion should be maintained in those patients with pre-existing SCI who present with abdominal trauma.

Abdomen, Acute↗
PubMed1998

Glucose concentration in human subcutaneous adipose tissue: comparison between forearm and abdomen.

There is still controversy about the relation between the glucose concentration in the subcutaneous (sc.) adipose tissue and the blood plasma. Depending on the technique applied, the glucose concentration in sc. tissue varies between 50% and 100% of the plasma glucose concentration. In the present study the sc. glucose concentration of forearm and abdomen in seven healthy volunteers was compared with plasma glucose by applying the microdialysis technique with very low flow rates. A microdialysis probe implanted into the subcutaneous tissue of abdomen and forearm was perfused with a flow rate of 1 microl/4 min. The dialysate was sampled in three 2-h-fractions in the fasting state and in one 2-h-fraction during a hyperglycemic clamp (216.9+/-3.4 mg/dl) (mean +/- SEM). The mean recoveries of the plasma glucose were 91.1+/-4.1% in the forearm and 82.7+/-18.0% in the abdomen. The recoveries in the sc. tissue of abdomen and arm were not significantly different. However, the arm showed significantly (p < 0.014) less interindividual variance (range 73.2- 103.2%) than the abdomen (range 50.6-117.1%) and appears to be the preferable implantation site. The recovery remained constant during the investigation.

Abdomen↗
PubMed2000

Selective surgical indication in the management of neutropenic children presenting with acute abdomen.

As the treatment of pediatric malignancies improves and survival increases, the diagnosis of acute abdomen in these patients also becomes more common. Nevertheless, the management of this condition is still controversial. The authors report their experience in treating 12 neutropenic children with acute abdomen. The charts of 12 neutropenic patients with a diagnosis of acute abdomen treated at Boldrini Children's Cancer Center in Campinas, Brazil, between 1991 and 1996, were reviewed. Therapeutic strategy included an initial period of bowel rest, general supportive measures, and broad-spectrum antibiotics while waiting for the neutrophil count to rise. Three patients recovered completely without surgery, 8 underwent late surgery without complications, and 1 died due to uncontrolled sepsis before surgery. The treatment of acute abdomen in neutropenic children remains controversial. As shown in the present series, an initial nonoperative approach with selective surgical indication appears to be safe and to yield good results. Supportive treatment, until the neutrophil count rises, followed by surgery, if necessary, appears to be a sound therapeutic approach for neutropenic children with acute abdomen.

Abdomen, Acute↗
PubMed1976

Heat exchange in relation to blood flow between thorax and abdomen in bumblebees.

1. The narrow passage within the petiole between thorax and abdomen is anatomically constructed so that counter-current exchange should retain heat in the thorax despite blood flow to and from the cool abdomen. 2. However, the counter-current heat exchanger can be physiologically circumvented. Exogenously heated bumblebees prevented overheating of the thorax by shunting heat into the abdomen. They also regurgitated fluid, which helped to reduce head temperature but had little effect on thoracic temperature. 3. Temperature increases in the ventrum of the abdomen occurred in steps exactly coinciding with the beats of the ventral diaphragm, and with the abdominal 'ventilatory' pumping movements when these were present. The ability to prevent overheating of the thorax by transport of heat to the abdomen was abolished when the heart was made inoprative. 4. At low thoracic temperatures the ventral diaphragm beat at a wide range or rates and with varying interbeat intervals, while the heart beat at a high frequency relative to the ventral diaphragm, but at a very low amplitude. However, when thoracic temperature exceeded 43 degrees C the amplitudes of both were high, and the interbeat intervals as well as the beating frequencies of the two pulsatile organs became identical in any one bee. Furthermore, heated bees engaged in vigorous abdominal pumping at the same frequency as that of their heart and ventral diaphragm pulsations. 5. The results indicate that the anatomical counter-current heat exchanger is reduced or eliminated during heat stress by 'chopping' the blood flow into pulses, and the blood pulses are shunted through the petiole alternately by way of a switch mechanism.

Abdomen↗