Altered cardiovascular and neurohumoral responses to head-up tilt after heart-lung transplantation

Heart-lung transplantation results in afferent and efferent denervation of the transplanted organs including interruption of the central connections from the low-pressure receptors in the atria and pulmonary veins. We investigated whether the cardiovascular and neurohumoral responses to the postural stimulus of head-up tilt were affected after transplantation. Responses in eight heart-lung transplant recipients were studied and compared with those in eight normal subjects matched for age and sex during passive head-up tilt at 45 degrees for 1 hour. The transplant group had a higher initial heart rate (99 +/- 2 versus 68 +/- 2 beats/min, p less than 0.001) and diastolic blood pressure (88 +/- 5 versus 76 +/- 2 mm Hg, p less than 0.05) than did the control group. The increases in heart rate and diastolic blood pressure during head-up tilt were similar in the two groups. Systolic blood pressure remained unchanged. The decrease in cardiac output (30% versus 18%, p less than 0.05) and the increase in systemic vascular resistance (52% versus 28%, p less than 0.05) were greater in the transplant group. Baseline levels of norepinephrine, epinephrine, vasopressin, and plasma renin activity were similar in the two groups. Atrial natriuretic peptide concentrations were higher in the transplant group (26 +/- 3.8 versus 9.7 +/- 1.6 pmol/l, p less than 0.001). During head-up tilt, plasma norepinephrine levels increased to a greater extent in the transplant group than in the control group (83% versus 53%, p less than 0.01), indicating an increased sympathetic response. In contrast, plasma renin activity increased significantly in the control group but not in the transplant group.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal functional response to dopamine during and after arteriography in patients with chronic renal insufficiency

The potential renal vasodilatory effect of dopamine in improving renal function after arteriography was studied. Sixty patients with preexisting renal insufficiency were prospectively randomized into two groups. Patients in the treated group (n = 30) received an infusion of dopamine for 12 hours starting at the beginning of arteriography. Patients who received placebo infusion with arteriography (n = 30) served as controls. The study was conducted in two different time intervals. In the first interval, serum creatinine levels and 12-hour creatinine clearance values were obtained before and immediately after arteriography in 12 patients in the dopamine group and 13 patients in the control group. In the second interval, the same variables were measured before arteriography and for 3 consecutive days after arteriography in 18 patients in the dopamine group and 17 patients in the control group. Serum creatinine levels became significantly elevated in the control group on the 1st day and remained so on the 3rd day after arteriography, whereas the dopamine group did not show significant elevation of these levels. Creatinine clearance decreased in the control group on the 1st day, but this deterioration was not sustained on the 3rd day. In the dopamine group, there was no deterioration in creatinine clearance on either day, and mean effective renal plasma flow during and after arteriography was greater.

The Drosophila Fos-related AP-1 protein is a developmentally regulated transcription factor

Drosophila AP-1 consists of two proteins (dFRA and dJRA) that have functional and structural properties in common with mammalian Fos and Jun proto-oncogene products. Here, we report the isolation and characterization of cDNAs encoding the full-length dFRA and dJRA proteins. The predicted amino acid sequences reveal that both proteins contain a bipartite DNA-binding domain consisting of a leucine repeat and an adjacent basic region, which are characteristic of members of the AP-1 family. By using protein translated in vitro or expressed in Escherichia coli, we demonstrate that dFRA, in contrast to the mammalian cFos proteins, recognizes the AP-1 site on its own and activates transcription in vitro in the absence of dJRA or Jun. Heteromeric complexes formed between dFRA and dJRA bind the AP-1 site better than either protein alone, and the two proteins activate transcription synergistically in vitro. In the developing embryo, dFRA mRNA is first expressed in a limited set of cells in the head and is later restricted to a subset of peripheral neurons, several epidermal cells near the muscle attachment sites, and a portion of the gut. In contrast, dJRA appears to be uniformly expressed at a low level in all cell types. These results indicate that dFRA is a developmentally regulated transcription factor and suggest that its potential interplay with dJRA plays an important role in cell-type-specific transcription during Drosophila embryonic development.

Beneficial effect of adenosine during reperfusion following prolonged cardioplegic arrest

STUDY OBJECTIVE

The aim of the study was to investigate the effect of reperfusion with adenosine after prolonged cardioplegic arrest in the isolated working rat heart.

DESIGN

After 3 h or hypothermic (20 degrees C) ischaemic arrest with multidose (every 30 min) infusions of St Thomas's Hospital cardioplegic solution No 1, rat hearts were reperfused with either ordinary perfusion fluid (Krebs-Henseleit bicarbonate buffer) or with additional adenosine (1 mg x litre-1) for 15 min prior to assessing recovery of function.

EXPERIMENTAL MATERIAL

Hearts (n = 10) in each group) were obtained from male rats weighing 250-300 g.

MEASUREMENTS AND MAIN RESULTS

Mean coronary flow during the period of reperfusion was increased from 11.8(SEM 0.8) ml x min-1 with ordinary perfusate to 17(0.7) ml x min-1 with adenosine reperfusate (p less than 0.001). Mean recoveries of functional indices (as percent of preischaemic control values) in hearts receiving ordinary reperfusates v adenosine reperfusates were: peak aortic pressure 76.2(2.8)% upsilon 86.9(2.2)%, dP/dt 35.6(6.0)% upsilon 66.2(4.3)%, aortic flow 26.1(7.4)% upsilon 60.9(4.2)%, coronary flow 50.1(3.4% upsilon 75.6(3.6)%, and cardiac output 31.4(6.4)% upsilon 64.5(3.2)%. Recovery of all indices was significantly superior with adenosine than without (peak aortic pressure p less than 0.01, other indices p less than 0.001). A parallel series of experiments showed that the nucleotide content of both groups was similar at the end of the 15 min reperfusion period.

CONCLUSIONS

Improvement in functional recovery occurs with low dose adenosine during reperfusion. This is likely to be due to an increase in coronary flow to the microvasculature rather than to an increase in intramyocardial ATP.

Response to dynamic exercise in cardiac transplant recipients: implications for control of the sodium regulatory hormone atrial natriuretic peptide

1. To study the importance of cardiac innervation in the regulation of atrial natriuretic peptide, plasma atrial natriuretic peptide levels were measured during symptom-limited, graded exercise on a cycle ergometer in seven male orthotopic cardiac transplant recipients. 2. Resting plasma atrial natriuretic peptide was significantly higher in the transplant recipients than in two control groups, one matched to the transplant recipients (group I) and the other to the age of the donor heart (group II). 3. The response to exercise of the cardiac transplant recipients was compared with the response of control group II. Mean maximal work load achieved with exercise was around 40% lower in the cardiac transplant recipients. During exercise, plasma atrial natriuretic peptide levels increased in both the cardiac transplant recipients and the control subjects. The increase in plasma atrial natriuretic peptide with exercise was greater in absolute, but less in percentage, terms in transplant recipients than in the control subjects. 4. The increase in mean arterial pressure with exercise was similar in patients and in control subjects; however, heart rate increased in the patients by only 33% compared with a rise of 151% in the control group. 5. These results provide insight into the control of the sodium regulatory hormone atrial natriuretic peptide. First, factors other than a change in heart rate appear of importance in the regulation of atrial natriuretic peptide. Secondly, these findings suggest that cardiac innervation is not of dominant importance in the modulation of atrial natriuretic peptide secretion.

Improved high-performance liquid chromatographic method for analysis of cyclosporin A using an automated sample processor

Transplant patients receiving the immunosuppressive drug cyclosporin A require regular monitoring to maintain levels within a narrow therapeutic range. A stable, accurate and reproducible high-performance liquid chromatographic method for analysis of cyclosporin A in whole blood has been developed using the Varian Advanced Automated Sample Processor. Starting with 200 microliters of blood, absolute recovery of both cyclosporin A and the internal standard was 81% with a detection limit of 12.5 ng/ml. The assay is perfectly linear over the range 0-1000 ng/ml (r2 = 1.0). At a concentration of 250 ng/ml, the coefficient of variation, both between samples and between assays, is 1.87%. Chromatographic cycle time is 10.2 min per sample. Up to eighty samples can be processed by one person in a working day, with final results within 16 h.

Lectin binding identifies a subpopulation of neurons in chick dorsal root ganglia

We screened a variety of lectins with different sugar specificates to determine whether subpopulations of dorsal root ganglion (DRG) neurons in the chick can be distinguished by the carbohydrates they express. Of the 15 lectins tested only those that recognize N-acetylgalactosamine (galNac) residues labeled a subset of DRG neurons. For example, Dolichos biflorus (DBA) labeled a population of small-diameter neurons in the dorsomedial DRG and their terminals in the dorsal horn in hatchling chicks. Staining of live neurons in vitro demonstrated that DBA was binding to the cell surface. Labeling first appeared in sensory neurons at about St.38 (E12) and in dorsal horn laminae 1 and 2 at about St.42 (E16). Fainter labeling appeared somewhat later in lamina 3, after hatching. Labeling of the tissue sections was eliminated by chloroform: methanol extraction and reduced by alpha-N-acetylgalactosaminidase digestion, but survived trypsinization. Together these results suggest that a subset of DRG neurons in the chick can be identified by the presence of a cell surface glycoconjugate, perhaps a glycolipid, containing terminal alpha-linked galNac residues.

Intestinal absorption of arachidonic acid in experimental azotemia

The effect of renal failure (RF) on intestinal absorption of dietary fatty acids is not known. We studied the intestinal absorption of arachidonic acid (AA) in rats with experimental short-term (2 weeks post-subtotal nephrectomy) and long-term (5-6 weeks post-subtotal nephrectomy) RF. The results were compared with those obtained in sham-operated animals on liberal food intake (NL) and in those pair-fed (PF) with the respective RF groups. In vivo perfusion and in vitro incubation experiments were performed at a wide range of AA concentrations. The rates of AA transport determined both in vivo and in vitro were significantly lower in the short-term RF group than those found in the NL controls and the PF animals who showed comparable values. In contrast animals with long-term RF exhibited an increased rate of AA transport as compared with the respective controls. The observed changes in the transport rates appeared to parallel directional changes in mucosal mass which was reduced in animals with short-term RF and restored in those with long-term RF.

Altered sympathoadrenal response to dynamic exercise in cardiac transplant recipients

The cardiac denervation produced by heart transplantation modifies the physiological response to exercise. The cardiorespiratory and sympathoadrenal response of seven "healthy" orthotopic heart transplant recipients was compared to seven age matched normal subjects during progressive dynamic exercise. The initial venous noradrenaline concentration tended to be higher in the transplant group, at 3.6 (SEM 0.6) v 2.9(0.2) nmol-litre-1 (NS). Noradrenaline concentrations were significantly higher in the transplant group during exercise (p less than 0.05, by analysis of variance). The transplant recipients reached a lower maximum workload than the normal subjects, at 102(8) v 170(10) watts (p less than 0.01) and the peak noradrenaline concentrations were similar in the two groups. The fall in noradrenaline concentrations after exercise was similar in the two groups. This showed that noradrenaline clearance was normal in the transplant recipients and the higher noradrenaline level reflected increased sympathetic activity. Despite the normal peak noradrenaline concentration, the transplant recipients achieved lower maximum heart rates than the normal subjects, at 142(3) v 181(5) beats min-1 (p less than 0.01). Adrenaline concentrations were similar in the two groups during submaximal exercise and tended to be lower in the transplant recipients at maximal exercise. The increased sympathetic activity may be a response to altered cardiac performance because of efferent cardiac denervation or to loss of tonic inhibition of sympathetic activity by cardiac receptors due to afferent denervation. Both circulating noradrenaline and adrenaline appear to play a significant role in the heart rate response to exercise after cardiac transplantation.

The effects of local anesthetics on maternal and neonatal platelet function

The effects of bupivacaine (B), lidocaine (L) and 2-chloroprocaine (C) on maternal (M) and neonatal (N) platelet function were studied using in vitro beta-thromboglobulin (beta-tg) release (radioimmunoassay), and in vitro platelet aggregation. Aggregation produced by adenosine diphosphate (ADP), epinephrine and collagen was measured in the presence of 1, 10, 100, 500 or 1000 micrograms/ml concentrations of B, L or C. In addition, spontaneous in vivo beta-tg release was measured in M and N blood. In vivo beta-tg level in M and N blood was approximately double that in non-pregnant subjects (p less than 0.025). In vitro beta-tg release in M and N samples was inhibited only at concentrations exceeding 1000 micrograms/ml, and the inhibition was less in M and N samples than in non-pregnant subjects. None of the anesthetics inhibited aggregation of M or N platelets at 1 and 10 micrograms/ml. Only concentrations of 500 micrograms/ml or greater consistently inhibited platelet aggregation produced by the three aggregants in M and N samples, and L was the least effective of the three agents. Neonatal platelet aggregation was affected more by local anesthetics than was maternal aggregation. It is concluded that plasma local anesthetic concentrations achieved during normal maternal epidural anesthesia do not affect M or N platelet aggregation or beta-tg release.

Umbilical artery velocity waveforms: poor association with small-for-gestational-age babies

A total of 205 high-risk pregnancies was studied using continuous wave Doppler ultrasound examination of the umbilical artery to investigate the ability of the test to detect small-for-gestational-age (SGA) infants. The waveforms were analysed by calculating a ratio of the peak systolic to end diastolic frequency (A/B ratio). An A/B ratio greater than 95th centile from our derived normal values was classified as abnormal. Three outcome variables were examined: birthweight for gestational age, the standard deviation birthweight score and the ponderal index. Although of the 56 pregnancies with an abnormal Doppler result 34 (61%) were associated with a SGA infant, only 41% of all the SGA infants had an abnormal Doppler result. Alternative measures of growth, the ponderal index and the SD birthweight score, showed that on average the babies in the Doppler abnormal group were smaller than those in the Doppler normal group, but the overlap between the normal and abnormal groups was large. Therefore although Doppler ultrasound appears to identify groups of smaller babies, it does not identify individual pregnancies where the baby will be small at birth.

Counselling for prenatal diagnosis of sickle cell disease and beta thalassaemia major: a four year experience

A non-directive programme of prenatal counselling was used during a four year period. Forty-three couples at risk for having a baby with a haemoglobinopathy were identified. Prenatal diagnosis was offered in 19 pregnancies to 14 couples at risk of having a baby with sickle cell anaemia and in two pregnancies in two couples at risk of a baby with beta thalassaemia major, who presented before the 18th week of pregnancy. Six couples at risk for sickle cell anaemia accepted prenatal diagnosis in 10 pregnancies, as did both couples at risk for thalassaemia. Couples who were eligible for prenatal diagnosis but refused it tended not to have been informed about sickle cell disease before counselling, one partner was more frequently absent at the time of the initial counselling session, or they either had no children with sickle cell disease or the children were not severely affected. Other factors influencing their decision included a poor obstetric history and rejection of abortion, mainly on moral grounds. The approximately 50% uptake of prenatal diagnosis in this initial study highlights the complex issues involved. Our experience indicates that with systematic screening and counselling in the antenatal clinic, and with increased awareness of the haemoglobinopathies, couples at risk will be in a better position to make informed decisions.

Effect of contrast media on prostaglandin synthesis in vivo

Since systemic reactions to contrast media (CM) in patients often resemble pathophysiologic conditions associated with prostaglandin metabolites prostacyclin (PGI2), and thromboxane B2 (TXB2), plasma levels of these mediators are likely to provide an index of CM pathogenesis. In this study, patients undergoing peripheral arteriography were injected either with a hyperosmolal CM sodium diatrizoate or with a newer low osmolal CM, iohexol. Arterial blood samples were collected before and after the procedure. Prostacyclin and thromboxane were quantified as 6 ketoprostaglandin F1a (PGF1a) and TXB2 by using radioimmunoassay kits. Diatrizoate caused prostaglandin I2 (PGI2) release in 60% of patients, whereas 66% receiving iohexol also exhibited increased levels of PGI2 in their plasma. TXB2 concentration remained unchanged. No clinically adverse reactions were seen following the procedure. These results indicate that both high and low osmolality CM are capable of stimulating vascular endothelium, thereby causing prostacyclin release. Molecular mechanisms, however, remain to be determined.

Adult T-cell leukemia/lymphoma in Brooklyn

Fifteen patients with adult T-cell leukemia/lymphoma (ATLL) were identified in less than a two-year period in the Crown Heights-Bedford Stuyvesant section of Brooklyn, NY. All patients were black; nine patients originated from the Caribbean islands and six from the southern United States. Two of the patients were father and daughter, the first evidence of familial occurrence in the United States. Their clinical course was similar to that of previously described patients with this disorder. To our knowledge, these 15 patients represent the largest series of ATLL reported in the United States. We recommend that ATLL be seriously considered in the differential diagnosis of patients with non-Hodgkin's lymphoma, mycosis fungoides, lymphatic leukemia, or hypercalcemia.

The effect of 3,5,3'-triiodothyronine on leucine uptake and incorporation into protein in cultured neurons and subcellular fractions of rat central nervous system

Previous studies have shown that nuclear thyroid hormone receptors in rat brain are preferentially localized within neurons. These cells also synthesize protein at a high rate, and the aim of the present study was to investigate any relationship between these two characteristics. In this paper we have shown that T3 stimulates leucine uptake and incorporation into protein in primary cell cultures of neurons. Stimulation was apparent with concentrations of hormone as low as 1.25 nM and increased in a dose-dependent manner up to 10 nM T3. However, the rapidity of the effect (evident at 25 min, and significant at 40 min) suggests that protein synthesis is stimulated at the level of translation, rather than transcription. More detailed study with 5 nM T3, revealed that incorporation into both soluble (cytoplasmic) and insoluble (membrane-associated) protein fractions was stimulated to similar degrees, and therefore the effect on protein synthesis was general. Furthermore, T3-mediated stimulation of leucine uptake into neurons was completely abolished in the presence of the protein synthesis inhibitors, actinomycin D and cycloheximide, and therefore the effect on leucine uptake was attributed to an increased requirement for the amino acid in protein synthesis (pleiotrophic effect). Parallel studies conducted with synaptosomes and mitochondria isolated from the central nervous system of adult euthyroid animals revealed that 5 nM T3 was without effect on leucine uptake and incorporation into protein. Possible reasons for this lack of effect are discussed.

Animal and human studies of a new 99mTc labelled phosphine-isocyanide complex with possible applications to radionuclide ventriculography

A new 99mTc-phosphine-isocyanide complex with the general structure [99mTc (DEPE)2(CNR)2]+ has been synthesised and tested in animals and one human. In three animal species (rat, rabbit, dog), the complex is an efficient myocardial imaging agent, while in humans it remains in the blood pool. The complex is 100% protein bound in animals and humans, but whereas in humans it is attached to a 51.5 kdalton protein (probably prealbumin), in rabbits it appears to be bound to a larger macromolecule (M.W. greater than 100 kdalton). The efficiency of the complex for blood pool labelling was tested in a human volunteer and compared with the standard in vivo red cell labelling technique with stannous pyrophosphate. A satisfactory radionuclide angiogram could be performed with less than 370 MBq of the complex. The count rate for the complex (cps/MBq) was 15% higher than that obtained with the labelled red cells and the absence of splenic activity was notable. In humans this complex appears to be an efficient blood pool labelling agent which might be useful for radionuclide ventriculography.

Monoclonal antibodies can enhance the biological activity of thyrotropin

In this work we demonstrate that monoclonal antibodies (MABs) to TSH can enhance the biological actions of TSH in vivo. Hypopituitary Snell dwarf mice were injected with TSH (25, 50, or 100 mU/day) alone or complexed with MAB-GC73 once per day for 5 days; control animals received PBS. Radioactive sulfate (35SO4(2-)) was also injected on the fifth day and animals were killed 20 h later. Thyroids were removed for histology, blood taken for T4 estimations by RIA, and 35SO4(2-) uptake into costal cartilage in vivo was measured. In control mice thyroid histology revealed small follicles comprised of small flattened epithelial cells with a high nuclear-cytoplasmic ratio; colloid was dark with little vacuolation. In animals treated with TSH alone there was moderate evidence of activation in most of these features. However, a marked response was noted in animals treated with TSH plus MAB-GC73; characteristically, there was little interfollicular tissue and the follicles, which were large and comprised of cuboidal cells, contained pale, finely vacuolated cytoplasm. Both TSH alone and TSH complexed with MAB-GC73 promoted a significant dose-dependent increase in serum T4 levels. The two higher doses of TSH plus MAB-GC73 promoted a significantly greater increase in serum levels of T4 than that in groups receiving the same dose of TSH alone. Uptake of 35SO4(2-) into costal cartilage showed a significant correlation with serum T4 levels. In similar experiments significant increases in salivary gland epidermal growth factor content of male dwarf mice were observed. This work demonstrated that MAB enhancement of hormone action is not restricted to human GH, suggesting a more general phenomenon.

Modulation of estrogen receptor by insulin and its biologic significance

It has been proposed that a nonsteroidal hormone such as insulin may directly exert an influence through estrogen receptors and alter the biologic behavior of steroid hormone target tissue. The implication of such a proposal is that diabetes may alter the outcome of estrogen receptor-positive tumors such as breast or endometrial carcinomas. To evaluate the effect of insulin on a receptor-positive tumor, we examined the direct effect of insulin on an estrogen receptor and its subsequent biologic effect on a receptor-positive endometrial carcinoma model in vitro and in vivo. An in vitro experiment demonstrated that when the estrogen receptor-positive cell line was grown in serum-free media with low insulin, there was a loss of intracellular receptors for estrogen. This loss of estrogen receptors was also associated with increased growth rate as reflected by increased thymidine uptake. Similarly, in vivo experiments demonstrated that a diabetic host with a high blood glucose level and a low insulin level exhibited development of growth of a receptor-negative tumor with accelerated growth rate in contrast to growth of a receptor-positive tumor with slower growth rate in a normal host with normal serum insulin and blood glucose levels. Data suggest that insulin may modulate the growth of estrogen receptor-positive tumors through its direct effect on estrogen receptors.

The significance of increasing caesarean section rates

Obstetric intervention has been the subject of much recent criticism from both the medical profession and consumer groups who point to increasing caesarean section rates and question their justification. This article examines the indications for caesarean section and assesses the relative benefits and disadvantages.