Malignant mixed tumor (carcinosarcoma) of the pancreas: a case report supporting organ-induced differentiation of malignancy

BACKGROUND

We present an unusual case of a malignant mixed tumor (carcinosarcoma) of the head of the pancreas that was surgically resected and whose tissue pathologic condition supported the concept of organ-induced differentiation of malignancy.

METHODS

After a pancreaticoduodenectomy, tissue sections from various anatomic regions of the tumor were studied by routine histologic examination and immunocytochemistry. Genomic DNA from various regions of the tumor was extracted and digested with Hpa II, and a 511 bp region of the hypoxanthine phosphoribosyltransferase gene was amplified with the polymerase chain reaction to assess clonality.

RESULTS

The pathologic findings revealed areas of both adenocarcinoma and leiomyosarcoma, but these disparate areas were not randomly distributed but rather were polar in nature. The adenocarcinomatous areas localized to the tumor within the head of the pancreas, an area of normal ontogenetic glandular development, whereas the leiomyosarcomatous areas localized to regions of the tumor infiltrating the duodenal wall, an area of normal ontogenetic smooth muscle development. Both the adenocarcinomatous and the leiomyosarcomatous areas showed evidence of monoclonality and clonal identity.

CONCLUSIONS

This interesting polar distribution of histologic patterns illustrated by this malignant mixed tumor (carcinosarcoma) supports the hypothesis of organ-induced differentiation of malignancy.

Inhibition of matrix metalloproteinases by N-carboxyalkyl peptides

An extensive study of the requirements for effective binding of N-carboxyalkyl peptides to human stromelysin, collagenase, and to a lesser extent, gelatinase A has been investigated. These efforts afforded inhibitors generally in the 100-400 nM range for these matrix metalloproteinases. The most significant increase in potency was obtained with the introduction of a beta-phenylethyl group at the P1' position, suggesting a small hydrophobic channel into the S1' subsite of stromelysin. One particular compound, N-[1(R)-carboxyethyl]-alpha(S)-(2-phenylethyl)glycyl-L-leucine,N- phenylamide (79a), is relatively selective for rabbit stromelysin with a K(i) = 6.5 nM and may prove useful for elucidating the role of endogenously-produced stromelysin in lapine models of tissue degradation.

Mitochondrial COII sequences and modern human origins

The aim of this study is to measure human mitochondrial sequence variability in the relatively slowly evolving mitochondrial gene cytochrome oxidase subunit II (COII) and to estimate when the human common ancestral mitochondrial type existed. New COII gene sequences were determined for five humans (Homo sapiens), including some of the most mitochondrially divergent humans known; for two pygmy chimpanzees (Pan paniscus); and for a common chimpanzee (P. troglodytes). COII sequences were analyzed with those from another relatively slowly evolving mitochondrial region (ND4-5). From class 1 (third codon position) sequence data, a relative divergence date for the human mitochondrial ancestor is estimated as 1/27 th of the human-chimpanzee divergence time. If it is assumed that humans and chimpanzees diverged 6 Mya, this places a human mitochondrial ancestor at 222,000 years, significantly different from 1 Myr (the presumed time of an H. erectus emergence from Africa). The mean coalescent time estimated from all 1,580 sites of combined mitochondrial data, when a 6-Mya human-chimpanzee divergence is assumed, is 298,000 years, with 95% confidence interval of 129,000-536,000 years. Neither estimate is compatible with a 1-Myr-old human mitochondrial ancestor. The mitochondrial DNA sequence data from COII and ND4-5 regions therefore do not support this multiregional hypothesis for the emergence of modern humans.

Surgical management of recurrent carpal tunnel syndrome

An approach to the surgical management of recurrent carpal tunnel syndrome was evaluated in 30 patients with 35 involved wrists. This includes internal neurolysis of the median nerve and early post-operative mobilization of the wrist and fingers. The preferred surgical approach is through a second, more ulnar incision. Clinical assessment of sensorimotor function was converted into a numerical score ranging from zero (normal) to 9 (anaesthesia) and 10 (atrophy, severe). The average pre-operative score was mean 6.5 and median 7. At a mean follow-up of 23.5 months, the average post-operative score was mean 1.8 and median 0, a statistically significant improvement (P < 0.001).

New mouse primary retinal degeneration (rd-3)

A new mouse retinal degeneration that appears to be an excellent candidate for modeling human retinitis pigmentosa is reported. In this degeneration, called rd-3, differentiation proceeds postnatally through 2 weeks, and photoreceptor degeneration starts by 3 weeks. The rod photoreceptor loss is essentially complete by 5 weeks, whereas remnant cone cells are seen through 7 weeks. This is the only mouse homozygous retinal degeneration reported to date in which photoreceptors are initially normal. Crosses with known mouse retinal degenerations rd, Rds, nr, and pcd are negative for retinal degeneration in offspring, and linkage analysis places rd-3 on mouse chromosome 1 at 10 +/- 2.5 cM distal to Akp-1. Homology mapping suggests that the homologous human locus should be on chromosome 1q.

Comparison of continuous single layer polypropylene anastomosis with double layer and stapled anastomoses in elective colon resections

The documented leak rate of the continuous single layer polypropylene (CSLP) anastomosis in elective colon resection is 0-6 per cent. It is more cost effective than stapling (S), and should be faster and easier to perform than the double-layer (DL) technique. However, there have been no reported series comparing the outcome of the CSLP anastomosis with the DL and S techniques. We reviewed the charts of 100 patients with elective colon resections. Eighty-four had data sufficient for analysis. There were 44 CSLP, 21 DL, and 19 S. The groups were comparable with respect to 12 preoperative variables. Proportionately more large-small bowel anastomoses were performed in the S group, and no patient in the S group was actively taking steroids. Clinical outcome was assessed. All leaks were clinically apparent and documented with contrast enema or laparotomy. The leak rate for the CSLP was 6.8 per cent (3/44). Two of the three patients with leaks were taking steroids. There were two leaks in the DL group (9.5%), one of which was taking steroids, and no leaks in the S group. The difference in leak rate between the three groups was not statistically significant. The average cost for CSLP at our institution is $4.00 compared with $8.00 and $35.00 for the DL and S, respectively. We conclude that the CSLP is a reasonable and safe alternative to DL and S anastomoses.

Upregulation by retinoic acid of interleukin-2-receptor mRNA in human T lymphocytes

It was previously demonstrated that retinoic acid (RA) can enhance the functional responses of human T lymphocytes by increasing surface IL-2R alpha chain protein expression on proliferating T blasts, resulting in augmented IL-2-dependent growth. In the present study, we used IL-2-maintained lymphoblasts generated from human thymocytes to show that RA enhancement of IL-2R alpha is accompanied by an increase in steady-state levels of IL-2R alpha mRNA. This increase occurred within 1 hr after the addition of RA to the culture and was inhibited by the presence of the protein synthesis inhibitor cycloheximide. RA did not alter the stability of either IL-2R alpha on the cell surface or IL-2R alpha mRNA, suggesting regulation by RA at the level of transcription. This contention was supported by the demonstrated ability of RA to activate the IL-2R alpha promoter in a chloramphenicol acetyltransferase plasmid construct that was transfected into the blast cells. In addition to inducing IL-2R alpha expression, RA also increased the surface expression and mRNA levels of IL-2R beta, the 75-kDa component of the IL-2 receptor that mediates IL-2 signal transduction. These new findings showing regulation by RA of both IL-2R alpha and IL-2R beta suggest multiple pathways by which this retinoid can modulate functional IL-2 receptors.

Further clinical use of the interposition arteriovenous loop graft in free tissue transfers

The use of an arteriovenous fistula (AVF) to afford vascular access for free tissue transfer is described in 11 consecutive patients from a 1 year period. The leg was the site of pathology in six cases, and a reversed saphenous AVF to the femoral vessels was created. In the remaining five cases, those in the head and neck and arm regions, the recipient vessels varied. The mean patient age was 37.7 years, and ten of 11 patients were male. Etiologies of defect were automobile accidents in six cases, neoplasm in three, and gunshot wound and electrical injury in one patient each. Mean ischemia time was 113 +/- 15 min. Mean length of AVF was 27.3 +/- 2.1 cm. All flaps survived. AVF was a useful technique in the current study. Several maneuvers were undertaken to minimize the risk of thrombosis. All patients were given aspirin prior to AVF creation. Patients received dextran 40 in the postanastomosis period for 5 days. Finally, every effort was made to create the AVF between large vessels, especially in the leg, to maximize blood flow.

Mechanistic studies on the human matrix metalloproteinase stromelysin

To probe the mechanism of stromelysin (SLN)-catalyzed peptide hydrolysis, we determined the pH dependence of kc/Km and solvent deuterium isotope effects on kc and kc/Km. pH dependencies of kc/Km were determined for the SLN-catalyzed hydrolysis of three peptides: Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Nle-NH2,Arg-Pro-Ala-Pro-Gln-Gln- Phe-Phe - Gly-Leu-NleNH2, and N-acetyl-Arg-Pro-Ala-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Nle-NH2 (cleavage at Gln-Phe bond). The pH dependencies are all bell-shaped with shoulders that extend from pH 7.5 to 8.5. The existence of a shoulder indicates that the reaction mechanism involves at least two routes to products. These curves are governed by three proton ionizations with pKa values of 5.4, 6.1, and 9.5. The solvent isotope effect measurements provided the following values: D(kc/Km) = 0.80 +/- 0.05 and D(kc) = 1.58 +/- 0.05. That D(kc/Km) and D(kc) are different suggests that the rate-limiting transition states for the processes governed by kc/Km and kc cannot be the same. We use these results, together with analogy to thermolysin catalysis, to develop a mechanism for SLN catalysis.

Accuracy of the Denver-II in developmental screening

One of the oldest and best known developmental screening tests was recently restandardized and revised as the Denver-II. Because it was published without evidence of its accuracy, the present study was undertaken with 104 children between 3 and 72 months of age attending one of five day-care centers. To determine the presence of developmental problems, children were administered individual measures of intelligence, speech-language, achievement, and adaptive behavior. A second psychological examiner, blind to the outcome of the diagnostic battery, administered the Denver-II. Developmental problems including language impairments, learning disabilities, mild mental retardation, and/or functional developmental delay were found in 17% of the children. The Denver-II identified correctly 83% and thus had high rates of sensitivity. However, more than half the children with normal development also received abnormal, questionable, or untestable Denver-II scores. Thus the test had limited specificity (43%) and a high overreferral rate. The alternative scoring method, categorizing questionable/untestable scores as normal, caused sensitivity to drop to 56% although specificity rose to 80%. Since neither scoring method produced acceptable levels of accuracy, an effort was made to locate the sources of accuracy and inaccuracy within the test. Only items in the language domain were modestly helpful in discriminating children with and without difficulties. The findings suggest that the authors of the Denver-II need to engage in further development of the instrument including revising scoring criteria and item placement in relation to children's ages. In the interim, test users should employ screening tests which are more accurate such as the Minnesota Inventories or the Battelle Developmental Inventory Screening Test.

The effect of tissue expansion on dermal fibroblast contraction

Tissue expansion alters the function of skin cells. We studied the effects of expansion on the contractile function of dermal fibroblasts using an in vitro model, the fibroblast-populated collagen lattice (FPCL). Spherical expanders were placed dorsally in 30 Sprague-Dawley rats; one-half were serially inflated. One, 2, and 4 weeks later, 5 rats from each group were killed. Fibroblasts were cultured from dermis overlying the expanders and mixed with collagen, medium, and serum in petri dishes to form FPCL. Fibroblasts from 5 rats that had not undergone surgery were cultured to make control FPCL. Contraction was assessed by measuring the areas of the FPCL. At 48 hours, FPCL containing expanded fibroblasts had contracted significantly less than those containing unexpanded or control fibroblasts. Four weeks of expansion resulted in less contraction than 1 or 2 weeks. Tissue expansion inhibits the in vitro contractile function of dermal fibroblasts in the rat in a time-related fashion.

Epidemiology and microbiology of diarrhoea in young Aboriginal children in the Kimberley region of Western Australia

Infectious diarrhoea is common in young Australian Aborigines and is one of the main causes for their unsatisfactory health standards with consequent widespread failure to thrive and undernutrition. Most published reports relate to patients in hospital or to hospital admission statistics and give little indication of the extent or severity of diarrhoeal disease in children in Aboriginal communities. The present investigation involved more than 100 Aboriginal children up to 5 years of age living in remote communities in the tropical north of Western Australia who were studied prospectively over a 12-month period.

Prefabrication of free flaps using the omentum in rats

The omentum used as a vascular carrier is a new experimental model for prefabrication of free flaps in the rat. A 2.5 x 4 cm patch of omentum with gastroepiploic vessels and its rich vascular arcades was transferred under a bipedicled 2.5 x 6 cm right abdominal panniculocutaneous flap. At subsequent time intervals (postoperative days 0, 3, 5, 7, and 14), the skin pedicles were divided and the skin flap was raised as a composite island flap vascularized only by the underlying omental patch. The composite flap was then sutured back in place. Prefabricated flaps examined postoperatively demonstrated a dye fluorescence index (DFI) of 4.60% +/- 2.82% and 1.67% +/- 4.08% flap survival (FS) in the day 0 group; in the day 3 group, 9.83% +/- 1.47% of DFI and 15.00% +/- 10.35% of FS; in the day 5 group, 28.39% +/- 5.25% of DFI and 86.0% +/- 12.74% of FS (P less than 0.05); in the day 7 group, 38.19% +/- 7.52% of DFI and 98.13% +/- 3.72% of FS (P less than 0.05); and, in the day 14 group, 49.55% +/- 6.70% of DFI and 100% of FS (P less than 0.05). India-ink injection and histologic examination confirmed revascularization of the overlying skin by day 5.

Sodium nitroprusside degenerates cultured rat striatal neurons

Incubation of a primary culture of rat striatal neurons with sodium nitroprusside (SNP), a known source of nitric oxide (NO), showed a concentration-dependent increase in cyclic GMP levels with an EC50 value of 13.7 microM. Twenty-four hours following incubation with 10 microM SNP, striatal neurons underwent degeneration as assessed immunohistochemically and biochemically. In contrast, potassium ferricyanate at concentrations up to 1 mM had no effect on striatal neuron viability. These results indicate that SNP has neurotoxic actions in-vitro, an effect that may involve NO as a second messenger.

Analysis of diuretic doping agents by HPLC screening and GC-MSD confirmation

The simultaneous analysis of 14 diuretics in human urine (belonging to five different pharmacological groups) by reversed-phase high-performance liquid chromatography (HPLC) with a diode-array detector was developed by using a gradient elution with acetonitrile and phosphate buffer containing propylamine hydrochloride on a Bondclone-ODS (10 microns) column. The method was applied to the screening test of several diuretics abused by athletes. The confirmation analysis was performed by gas chromatography-mass spectrometry with ion-selective detection (GC-MSD). The characteristic mass fragment ions obtained by electron-impact (EI) ionization (70 eV) provided sufficient identification of these diuretic agents. During the 1990 weight-lifting contest of Asia in Kao-Hsiung, Republic of China, one urine sample was found positive for the diuretic hydrochlorothiazide.

Formation of endothelium-derived relaxing factor in porcine kidney epithelial LLC-PK1 cells: an intra- and intercellular messenger for activation of soluble guanylate cyclase

Oxytocin, bradykinin, melittin and A23187 increased cyclic GMP levels through activation of soluble guanylate cyclase in cultured porcine kidney epithelial cells, LLC-PK1. NG-monomethyl-L-arginine, an inhibitor of endothelium-derived relaxing factor/nitric oxide formation, decreased both basal and stimulated levels of cyclic GMP in a concentration-dependent manner. L-Arginine, but not D-arginine, augmented basal as well as stimulated levels of cyclic GMP and prevented the inhibition induced by NG-monomethyl-L-arginine. Similar effects of L-arginine were also observed with L-argininamide, L-arginine ethyl ester, L-arginine methyl ester and the dipeptide L-arginyl-L-aspartic acid. NG-monomethyl-L-arginine did not affect cyclic GMP accumulation induced by sodium nitroprusside, an activator of soluble guanylate cyclase, and atrial natriuretic factor, an activator of particulate guanylate cyclase. Stimulatory effects of oxytocin, glyceryl trinitrate, sodium nitroprusside, bradykinin, melittin and A23187 on cyclic GMP accumulation were enhanced with superoxide dismutase and diminished with oxyhemoglobin. However, atrial natriuretic factor-induced cyclic GMP accumulation was not affected. Furthermore, endothelium derived relaxing factor-like activity was detected in the conditioned medium from LLC-PK1 cells stimulated with oxytocin. Based on these data, we conclude that endothelium-derived relaxing factor is produced in this cell type and participates in the regulatory mechanism of cyclic GMP formation as an intra- and intercellular messenger for activation of soluble guanylate cyclase.

Effects of retinoic acid on the in vivo growth of human neuroblastoma cells

We have investigated the effects of retinoic acid (RA) on the development and growth in nude mice of tumors derived from the human neuroblastoma cell line LA-N-5. When cells were treated with 4 x 10(-6) M RA in vitro there was a marked reduction in the number of mice developing tumors when compared to solvent-treated controls. In vivo treatment with RA reduced tumor formation when the retinoid was given for 5 days before tumor injection and continued for 14 days thereafter. In established tumors, RA inhibited progressive tumor growth. There was no demonstrable effect of RA in vivo on the morphologic phenotype of the tumor cells when these regimens were used. We conclude that oral retinoid administration may prove useful in inhibiting or arresting the growth of neuroblastoma, particularly when there is a small initial tumor burden.

Effects of 13-cis retinoic acid therapy on human antibody responses to defined protein antigens

We have evaluated the in vivo effects of 13-cis retinoic acid (13-cis RA) on human antibody responses to immunization with tetanus toxoid (TT) and keyhole limpet hemocyanin (KLH). Subjects with severe cystic acne were immunized with suboptimal doses (10 micrograms) of KLH 7 d and 3 months after starting retinoid therapy (13-cis RA, 1 mg/kg/day for 4 mo). A standard booster immunization with TT was given along with the initial KLH sensitization. A control group of acne patients received identical immunization regimens, but no 13-cis RA. Plasma retinoid levels were evaluated by reverse-phase HPLC and confirmed that blood-level concentrations of 13-cis RA and metabolites in these acne patients reached values previously demonstrated to be immunomodulatory in vitro. The retinoid had no effect on responses to TT as reflected by the characteristics of increased anti-TT IgG levels or the isotype distribution of the antibody. In contrast, the anti-KLH response was significantly enhanced in the 13-cis-RA-treated group. Whereas anti-KLH antibody was detected in only 4 of 13 control subjects after the secondary immunization, 10 of 13 retinoid-treated subjects had measurable levels of anti-KLH IgG (p less than 0.05). Among the responders, no differences were noted in the isotype distribution of anti-KLH antibody. These results showing enhanced anti-KLH responses induced by 13-cis RA therapy represent the first demonstration in humans that in vivo administration of a retinoid can modulate antigen-specific immune responses.

Characterization of ATP-stimulated guanylate cyclase activation in rat lung membranes

Many of the effects of ANP are mediated through the elevation of cellular cGMP levels by the activation of particulate guanylate cyclase. While the stimulation of this enzyme is receptor-mediated, the molecular mechanism of activation remains unknown. In this study we present evidence that ATP as well as its analogues adenosine-5'-O-(3-thiotriphosphate) (ATP gamma S) and adenylylimidophosphate (AMPPNP) activates guanylate cyclase from rat lung membranes and markedly potentiates the effect of ANP on the enzyme. The order of potency is ATP gamma S greater than ATP greater than AMPPNP. The enzyme activation by adenine nucleotide and ANP together is much more than the sum of the individual activations, suggesting that ATP may be the physiological component essential for the ANP-stimulated guanylate cyclase activation. The ATP gamma S-stimulated guanylate cyclase activity diminishes in the presence of various kinds of detergents, suggesting either that the conformation of an ATP binding site in guanylate cyclase is altered by detergents or that protein-protein interaction may be involved in the activation of guanylate cyclase by ATP. Guanylate cyclase from rat lung membranes is poorly activated by ANP and/or ATP gamma S after removing the cytosolic and weakly membrane-associated proteins or factors by centrifugation. Pre-incubation of the membranes with ATP gamma S retains enzyme activation after membrane washing. These results suggest either that ATP gamma S stabilizes the conformation of nucleotide binding site in guanylate cyclase from denaturation by membrane washing, or that the stimulatory effect of ATP on guanylate cyclase activity may be mediated by accessory proteins or non-protein cofactors which are lost during membrane washing, but remain bound to membranes by ATP gamma S pretreatment.

N omega-nitro-L-arginine: a potent inhibitor of endothelium-derived relaxing factor formation

Endothelium-derived relaxing factor (EDRF) released from cultured endothelial cells was assayed by examining changes in cyclic GMP levels of rat lung fibroblasts. N omega-nitro-L-arginine and NG-monomethyl-L-arginine inhibited basal and A23187-, ATP- and melittin-induced EDRF release, and the inhibition was prevented with L-arginine. The IC50 values of N omega-nitro-L-arginine and NG-monomethyl-L-arginine for EDRF release evoked with 1 microM A23187 were 230 nM and 16 microM, respectively. N omega-nitro-L-arginine and NG-monomethyl-L-arginine did not affect cyclic GMP accumulation in the fibroblasts with atrial natriuretic factor or sodium nitroprusside. Thus, N omega-nitro-L-arginine is 70 times more potent than NG-monomethyl-L-arginine as a specific inhibitor of EDRF formation/release.

Acute cerebral hemorrhage changes the nocturnal surge of plasma melatonin in humans

The diurnal rhythm of plasma melatonin was studied in 46 Chinese patients with acute cerebral hemorrhage. The state of consciousness of each patient was assessed clinically. The individual sites of lesion were determined by computerized tomography scanning. One to five days after stroke, blood samples were collected by venipuncture at 1000 and 1400 h in the daytime and 0200 and 0400 h at night. Plasma melatonin was extracted by dichloromethane and determined by radioimmunoassay. It was found that patients with lesions in the brain stem or in the third and lateral ventricles had melatonin levels significantly different from the other subjects in that these values were lower and lacking a nocturnal rise. These results are consistent with the presumptive retina-pineal pathway proposed in humans. Dramatic blunting or obliteration of the nocturnal melatonin surge in the blood was also observed in some patients with lesions in the frontal lobe, fronto-parietal lobe, parieto-temporal lobe, and basal ganglia. These brain regions are not involved in the retina-pineal pathway described in rodents or humans. Thus, our results suggest that brain regions other than the presumptive retina-pineal neural pathway may play an important role in the generation and/or regulation of the diurnal production and/or secretion of pineal melatonin in humans. However, a global functional disturbance caused by cerebral hemorrhage cannot be ruled out in some cases. It should be noted that many of the lesions leading to a change in the nocturnal rise of plasma melatonin were unilateral lesions. The significance of this finding is presently unknown. In addition, patients without a nocturnal rise of plasma melatonin were mostly comatose. They had lesions in the basal ganglion, fronto-parietal lobe, brain stem, and lateral and third ventricles. The latter findings suggest that in the brain, certain regions responsible for the state of consciousness of the individual may also be important to the dirunal rhythm of pineal melatonin secretion.

Stimulation and suppression of the mineralocorticoid hormones in normal subjects and adrenocortical disorders

In summary, maneuvers that affect the RAS stimulate or suppress solely aldosterone and 18-OHB and have little, if any, effect on DOC, 18-OHDOC, B, or cortisol. The magnitude of aldosterone response seems to be of equal magnitude for all stimulatory or suppressive maneuvers as used in the present protocols. Although primarily originating in the ZG, some secretion of 18-OHB from the ZF is evident by its disproportionate responses (in relation to aldosterone) to maneuvers challenging ACTH. The prompt and marked increases the 18-OHDOC and B after ACTH make them the most sensitive "markers" of the ZF steroid activity. The application of those maneuvers and MCH measurements to adrenal disorders should help to further characterize their pathophysiology.

Use of OKT3 monoclonal antibody in the treatment of acute cardiac allograft rejection

OKT3 is a murine monoclonal antibody that recognizes the T3 surface antigen present on mature T cells, and it has been used to successfully treat renal allograft rejection. We report our experience with OKT3 in the treatment of cardiac allograft rejection. Eight patients with endomyocardial biopsy evidence of moderate or severe rejection were given fourteen daily intravenous treatments of OKT3. Six of the eight patients had complete recovery following OKT3 therapy; one required additional steroid therapy for recurrence and one patient failed to respond. Five of the six patients with a complete response have experienced no further rejection (mean follow-up 437 days). Adverse reactions to OKT3 were common early in the treatment course, but were well tolerated. We concluded that OKT3 is a safe and effective treatment of cardiac allograft rejection and that a majority of patients experience long-term rejection-free periods.

Calcium-sensitive uptake of amino acids by human placental slices

The placenta supplies many nutrients to the fetus, including amino acids by active transport. Although the exact regulatory mechanism is unknown, a few studies have suggested a role for calcium in amino acid transport. Therefore, we examined the relationship between calcium and amino acid uptake by term human placental slices. Calcium depletion of slices significantly reduced uptake of alpha-aminoisobutyric (AIB), which is actively transported primarily by a sodium-dependent, carrier-mediated mechanism. Impairment of AIB uptake induced by calcium depletion was reversed by repletion with calcium but not with other divalent cations. In contrast, uptake of phenylalanine, which is transported primarily by a sodium-independent mechanism, was not affected by calcium depletion. Uptake of leucine and valine, which accumulate by both sodium-dependent and independent mechanisms, was partially affected by calcium depletion. Verapamil (10 microM), an inhibitor of transmembrane calcium flux, significantly reduced AIB uptake. Trifluoperazine, a calmodulin antagonist, also inhibited AIB uptake. Analysis of AIB uptake kinetic constants for control and calcium-depleted slices showed no change in the diffusion constant, a 37% reduction in Vmax, and a 2-fold increase in Km. The results indicate that calcium may be an important factor in the cellular regulation of active transport of amino acids.

Effect of delta-9-tetrahydrocannabinol on the in vitro uptake of alpha-amino isobutyric acid by term human placental slices

Tetrahydrocannabinol (THC), the active component in marijuana smoke, crosses the placenta and is a potential fetotoxic agent. In both human and animal studies, the most consistent fetal effect of THC is intrauterine growth retardation. Since fetal somatic growth is dependent on placental transfer of nutrients, including essential amino acids, we studied the effect of THC upon the in vitro uptake of amino acid by term human placental slices. Uptake of alpha-amino isobutyric acid was inhibited in a dose-dependent fashion, correlating with the log of the dose (1-100 microM THC; r = 0.945; p less than 0.01). Compared to control tissue, significant impairment of alpha-amino isobutyric acid uptake began at 20 microM THC. Similar results were found for valine. The time course (30-120 min) for alpha-amino isobutyric acid uptake showed linearity for both control and THC-(50 microM) treated tissue, but there was a marked reduction in the THC slope. Uptake of alpha-amino isobutyric acid was significantly reduced at all times. The sustained effect of THC was slightly, but significantly, reversed by removal of THC from the medium after 90 min of 50 microM THC exposure. Only partial reversal may have been due to the 15- to 20-fold accumulation of THC in the placental tissue. Uptake kinetics showed noncompetitive inhibition with decreased Vmax: control Vmax = 51.66 +/- 6.26 versus 50 microM THC = 26.96 +/- 6.22 (mmol/liter intracellular water per h) (p less than 0.01); and no change in diffusion constant (Km): control Km = 0.78 +/- 0.08 versus 50 microM THC = 0.80 +/- 0.09 (mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor uptake of 5-fluorouracil, methotrexate, and adriamycin vs gallium

Since the imaging pattern of 67Ga-citrate is well known, it can be the benchmark for evaluation of potential tumor imaging agents. Tritium labeled 5-fluorouracil, Adriamycin, (doxorubicin/Adria) and Methotrexate/Lederle were compared at 2 h to 67Ga-citrate at 2 and 48 h by percent uptake per gram of various tissues and tumor in rats implanted with Walker 256 carcinosarcoma. 67Ga at 48 h showed approximately three times more uptake in the tumor than 5 fluorouracil and eight times more than the others. 5 Fluorouracil showed approximately three times greater uptake than Methotrexate or doxorubicin and 1.4 times the 2 h uptake of 67Ga. 5 Fluorouracil shows potential as an imaging agent especially where the waiting time between injection and imaging must be short.

Inhibition of Escherichia coli heat-stable enterotoxin effects on intestinal guanylate cyclase and fluid secretion by quinacrine

Enterotoxigenic Escherichia coli may produce a heat-stable enterotoxin (ST) that causes diarrheal disease in humans and in animals ST activates particulate guanylate cyclase in intestinal mucosal cells and causes intestinal fluid secretion. In this study, we examined the effects of quinacrine on ST activation of guanylate cyclase and ST-mediated intestinal fluid secretion. Quinacrine significantly reduced ST activation of particulate guanylate cyclase in rat intestinal tissue. Additionally, quinacrine reduced ST-mediated fluid secretion in a rat intestinal loop assay (P less than 0.05). In the suckling mouse model, subcutaneous quinacrine (0.1 mumole/mouse) reduced ST-induced fluid secretion at a submaximally effective dose of the toxin, but it did not reduce ST-mediated fluid secretion at a near maximally effective dose. Quinacrine (0.1 mumole/mouse) did not significantly reduce intestinal fluid secretion induced by the analog of cyclic GMP, 8-bromo cyclic GMP. However, at a higher concentration of quinacrine (1 mumole/mouse), significant inhibition of 8-bromo cyclic GMP-induced secretion was observed. Inhibition by the antimalarial agent quinacrine of ST-induced fluid secretion, by a block prior to guanylate cyclase activation, suggests a possible role for a phospholipase early in the sequence of events of ST activation of guanylate cyclase. The results suggest that ST may activate membrane phospholipases prior to ST activation of guanylate cyclase.

The mineralocorticoid hormone pathways in hypertension with hyperaldosteronism

Simultaneous measurement of the 0800-hr plasma concentrations of deoxycorticosterone (DOC), corticosterone (B), 18-hydroxycorticosterone (18-OHB), aldosterone, 18-hydroxydeoxycorticosterone (18-OHDOC) and cortisol (F) in four types of primary aldosteronism provides evidence for primary adrenal disease. Elevated DOC with normal F concentrations in the presence of elevated 18-OHB and aldosterone, and suppressed renin concentration suggests a primary adrenal abnormality of the zona glomerulosa (ZG). Steroid production by the zona fasciculata (ZF), F, 18-OHDOC, and most often B, is normal. These patterns exist only for primary adrenal hyperplasia, aldosterone-producing adenoma (APA), and aldosterone-producing adrenocortical carcinoma (AP-Ca). Elevated DOC levels are rarely found in patients with idiopathic hyperaldosteronism (IHA or adrenal hyperplasia) and suggest that IHA is not a primary adrenal disorder and should be excluded from the syndrome of primary aldosteronism as they have been heretofore.

Regulation of the mineralocorticoid hormones in adrenocortical disorders with adrenocorticotropin excess

Chronic stimulation by adrenocorticotropin (ACTH) of the adrenal cortex produces different plasma mineralocorticoid hormone (MCH) patterns, depending on the amount of glucocorticoid hormones (cortisol) concurrently generated and the degree of activation of the renin angiotensin system (RAS). Patients with Cushing's disease or the ectopic ACTH-excess syndrome have normal or low production of the MCHs, aldosterone and 18-hydroxycorticosterone (18-OHB), by the zona glomerulosa (ZG), elevated cortisol and deoxycorticosterone (DOC) levels, and high-normal to elevated production of the MCHs corticosterone (B) and 18-hydroxydeoxycorticosterone (18-OHDOC) by the zona fasciculata (ZF). Prolonged administration of superphysiologic doses of ACTH to normal subjects yields similar patterns. Patients with simple virilizing 21-hydroxylase deficiency (21-OHD) have impaired ZF production of B and 18-OHDOC and elevated DOC, 18-OHB, and aldosterone secretion secondary to the superimposed RAS stimulation of the ZG. Patients with 17 alpha-hydroxylase deficiency (17 alpha-OHD) have elevated levels of the ZF MCHs DOC, B, 18-OHDOC, and 18-OHB and a functionally suppressed ZG. Patients with 11 beta-hydroxylase deficiency (11 beta-OHD) have only elevated production of DOC by the ZF and suppressed RAS and aldosterone. A significant negative correlation between cortisol and aldosterone concentrations suggests that cortisol is involved in the ACTH-mediated inhibition of aldosterone formation.

Radiation therapy before cystectomy in the management of patients with bladder cancer

During the preceding two decades, 309 patients with bladder cancer were treated by irradiation before cystectomy at the Memorial Sloan-Kettering Cancer Center. A radical tumour dose averaging 6000 cGy (rad) in six weeks was given to 104 patients who underwent radical cystectomy +/- one year later for persistent or recurrent cancer. Pre-operative pelvic irradiation was planned in 205 patients who received either 4000 cGy in four weeks (119) or 2000 cGy in one week (86) and underwent radical cystectomy after +/- six weeks and two days, respectively. The determinate five-year survival rates (41-43%) were similar with the three irradiation regimes; mortality under five years was mainly due to cancer recurrence locally and/or distally. Incidence of recurrence with radiation-induced stage reduction (21%) was lower, especially within the pelvis, than with no stage reduction (51%). Treatment results with planned pre-operative irradiation, especially in high stage tumours, were more favourable with the shorter 2000 cGy regimen of high fractional doses than with the conventionally fractionated 4000 cGy regimen.

Inhibition of Escherichia coli heat-stable enterotoxin by indomethacin and chlorpromazine

Purified heat-stable enterotoxin (ST) from a procine strain of enterotoxigenic Escherichia coli activates quanylate cyclase in particulate fractions of rat intestinal tissue and induces fluid accumulation in suckling mice. These effects of ST were examined in the presence of either indomethacin or chlorpromazine. We also examined the effects of these two drugs on fluid accumulation in suckling mice induced by the 8-bromo analog of cyclic guanosine monophosphate. Either indomethacin or chlorpromazine reduced ST activation of guanylate cyclase. Both drugs also reduced intestinal fluid accumulation in suckling mice that resulted from submaximal doses of ST (both P < 0.001). However, there was no reduction in fluid secretion by either drug when a maximally effective dose of ST was used, suggesting that inhibition of fluid secretion by both drugs can be overcome by increasing the ST dose and that a threshold level of guanylate cyclase activity results in maximal secretory response. Both drugs also reduced basal guanylate cylase activity in rat intestinal tissue and fluid secreton in suckling mice. Chlorpromazine also reduced intestinal secretion mediated by 8-bromo cyclic guanosine monophosphate (P < 0.001). These findings indicate that chlorpromazine interferes with the effects of ST both before and after its activation of guanylate cyclase, whereas indomethacin interfers with ST only before its activation of guanylate cyclase.

Activation of intestinal guanylate cyclase by heat-stable enterotoxin of Escherichia coli: studies of tissue specificity, potential receptors, and intermediates

Heat-stable enterotoxin (ST) of Escherichia coli increased guanylate cyclase activity in homogenates of rat and rabbit intestinal mucosa and stimulated intestinal fluid secretion in suckling mice. The ST effect on guanylate cyclase was dose-dependent, occurred without a time lag, and was confined to the particulate fraction. ST activation of guanylate cyclase was tissue-specific; ST did not alter activity of soluble or particulate rat liver, lung, heart, kidney, or cerebral cortex enzyme. The ST activity on guanylate cyclase and secretion was methanol-soluble and alkali-labile, and its effects were not altered by phentolamine, propranolol, or atropine. Monosialoganglioside did not reduce ST-induced secretion. However, indomethacin and butylated hydroxyanisole decreased the ST effect on both guanylate cyclase and secretion. Fluid secretion with ST sppears to result from specific activation of particulate intestinal guanylate cyclase. While adrenergic and cholinergic events are probably not involved in this process, the effects of ST may be mediated through prostaglandin synthesis or oxidative mechnanisms.

Adrenocorticotropin inhibition of mineralocorticoid hormone production

1. Adrenocorticotropin (ACTH)-induced steroidogenesis, obtained by continuous administration of ACTH for 3 days, produces in man (a) sustained elevations of plasma deoxycorticosterone and cortisol concentrations, (b) transient elevations of plasma aldosterone and 18-hydroxycorticosterone concentrations that return to near-control values, and (c) brisk initial increases in plasma 18-hydroxydeoxycorticosterone and corticosterone concentrations that fall to 20-68% of peak values 30 h thereafter. 2. Dexamethasone (8 mg/day, orally) treatment for 2 days in man permits a greater postural increase in plasma aldosterone and 18-hydroxycortisone concentrations. A dampening effect of ACTH is suggested. 3. An ACTH-initiated inhibition of 11 beta- and 18-hydroxylation is proposed to be operative in regulation of mineralocorticoid hormones.