Animal models as indicators of immunogenicity of therapeutic proteins in humans

Animal models have not been able to predict the immunogenicity of therapeutic proteins in humans reliably. The main issue is that administration of a human protein in an animal species is likely to be immunogenic. In non-human primate studies, we have seen a variety of responses; from little to no antibody response, to a strong neutralizing response, or even a cross-reactive antibody response. These have generally not correlated well with the immune response seen in humans. The route of administration, duration and schedule of dosing, the cumulative dosage of the protein, the pharmacological (i.e., immune altering) properties of the protein, as well as the purity of the clinical material can influence the immunogenicity. The animal studies should mimic these factors to the best extent possible for the animal model to be at all relevant to humans. Models do exist which provide valuable information to compare the immunogenicity of various compounds or routes of administration. Presumably, this 'relative' immunogenicity would be similar in humans. Additional characterization of transgenic mice, or use of homologous proteins, may help to establish better models to predict immunogenicity.

Lack of developmental neurotoxicity of MN rgp 120/HIV-1 administered subcutaneously to neonatal rats

The potential for neurotoxic effects was evaluated in rat off-spring after exposure in utero and/or during the neonatal period to a recombinant subunit vaccine of gp120 prepared from the MN strain of HIV-1 (MN rgp 120/HIV-1). Thirty pregnant female rats were given MN rgp120/HIV-1 with alum adjuvant, and 30 rats were given vehicle, once every 3 days from Day 1 of presumed gestation until parturition. One pup/sex/litter from treated and control group dams were given a daily subcutaneous injection, from Day 1 through Day 22 postpartum (PP) of vehicle, MN rgp120/HIV-1, MN rgp120/HIV-1 with alum, or MN rgp120/HIV-1 with QS-21 adjuvant. Neurobehavioral and physical development were evaluated (preweaning reflex and development, sexual maturation, motor activity, acoustic startle, passive avoidance, functional observational battery, and water M-maze testing), and tissues were processed for anatomical examination (whole and regional brain weights, and neuropathology). Administration of MN rgp120/HIV-1, with or without adjuvant, to pups did not cause any persistent effect on any parameter evaluated. Neurohistological examination did not reveal any pathological effects related to treatment. Thus, MN rgp120/HIV-1 alone or formulated as a vaccine does not cause neurotoxicity or developmental toxicity in neonatal rats after exposure in utero and/or during the neonatal period.

Vasculitis confined to the calves. Report of a case

Polyarteritis nodosa is a systemic disease of which limited forms have been reported, with the most common involving the skin. Only 13 cases with lesions confined to the calves have been reported to date. We report a new case.

Subchondral insufficiency fracture of the femoral head

We report two cases of subchondral insufficiency fractures of the femoral head. Clinical manifestations of this lesion are nonspecific. Radionuclide bone scanning demonstrates early hyperactivity. Initial roentgenograms are usually normal. Magnetic resonance imaging establishes the diagnosis and rules out other conditions.

Reproductive effects of chronic administration of murine interferon-gamma

Daily subcutaneous doses of 0.02, 0.2, or 2 mg/kg/d of recombinant murine interferon-gamma (rmuIFN-gamma) were given to mice on postnatal days 8 through 60 to determine effects on maturation, behavioral/ functional development, and reproductive capacity. Male mice receiving 2 mg/kg/d rmuIFN-gamma had delayed sexual maturation, reduced epididymal and testes weights, reduced sperm count and concentration, and sperm abnormalities (crimped flagellum). Mating performance and fertility were also reduced in the absence of altered histopathology of the testes. Males given 0.2 and 2 mg/kg/d had swelling and ulcerative dermatitis around the urogenital area, which were observed after sexual contact and attributed to a bacterial infection. Motor activity (time spent in movement) was decreased in all mice receiving 2 mg/kg/d. No microscopic changes observed in any organs were attributed to rmuIFN-gamma administration.

Atrial septal aneurysm. Morphological characteristics in a large population: pathological associations. A French multicenter study on 259 patients investigated by transoesophageal echocardiography

A strong association between interatrial septal aneurysm (IASA) and stroke has recently led many authors to consider IASA as a potential cardiac source of embolism. We studied the morphological characteristics and main associations of IASA in a large cooperative study based on transoesophageal echocardiographic examinations; 259 IASA were studied in 134 men and 125 women with a mean age of 59 +/- 15 years. Fifty-five percent of IASA were found to overlap the commonly described fossa ovalis region. IASA protruded into the right atrium in 90% of the cases. They appeared thin in 81% of the patients and highly mobile in 79%. Fifty-eight percent of patients had a history of systemic embolic events, while an atrial septal shunt was detected in 61% of the patients. In patients with an embolic event, only the mobility of IASA was significantly higher than in those with no embolic event. In nine cases a pulmonary embolism was associated with arterial embolism. Furthermore, we reported three cases of paradoxical embolism. However, the true demonstration of a thrombus within the IASA was quite rare.

CONCLUSION

IASA is probably an important risk factor for stroke. In patients with IASA and a history of embolic events, IASA may enhance migration of a thrombus constituted in situ or transiting through it. Marked mobility of IASA may also increase the risk of peripheral embolus.

Aortic occlusion in a patient with antiphospholipid antibody syndrome in systemic lupus erythematosus

A 41-year-old woman with systemic lupus erythematosus and lupus anticoagulant developed aortic thrombosis. The patient was receiving low dose aspirin. Aortography showed a complete obliteration of the infrarenal aorta. Computed tomography and magnetic resonance imaging showed no evidence of aortitis. The patient improved with medical treatment. Six other published cases are reviewed.

Cervical epidural infection. Four case-reports

The authors report four cases of cervical epidural infection, in two females (aged 58 and 82 years) and two males (aged 41 and 51 years). Risk factors were noninsulindependent diabetes mellitus in one patient and multiple myeloma treated by chemotherapy in another. Duration of cervical pain at evaluation was five to 15 days. Three patients had a fever and a neurologic deficit: one had brachial diplegia; the myeloma patient developed brachial diplegia after a lumbar puncture and the diabetic patient developed quadriplegia with respiratory disorders also after a lumbar puncture. Cerebrospinal fluid studies showed elevated protein levels with approximately 20 cells per mm3 and no pathogens in smears or cultures. Roentgenograms were normal at admission. The diagnosis was established by myelography (n = 2) and/or computed tomography (n = 2) and/or magnetic resonance imaging (n = 2). The infected area was anterior in three cases and posterolateral in one. Two to seven vertebral levels were affected. A Staphylococcus aureus was recovered from the blood cultures in all four cases and from a local specimen in one of the two patients who had a laminectomy. Of the two patients who did not have surgery, one had a normal neurologic evaluation and the other was an elderly patient with myeloma. In both, antimicrobial and corticosteroid therapy ensured complete resolution of the infection, and the myeloma patient recovered normal neurologic function. Residual neurologic loss was seen in one of the two surgically-treated patients. Two patients developed discitis.

Suppression of peritoneal macrophage phagocytosis of Candida albicans by opioids

Receptor-selective opioid agonists have been found to suppress the capacity of macrophages to ingest opsonized sheep erythrocytes. In an effort to characterize the immunomodulatory activity of opioids further, experiments were done to examine the uptake of Candida albicans by opioid-treated murine peritoneal macrophages. It was found that treatment with morphine and selective mu, i.e., DAMGO, delta, i.e., DPDPE, and kappa, i.e., trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]benzene-acetamide methanesulfonate, receptor agonists resulted a concentration-dependent suppression of both the percentage of phagocytic cells and the average number of ingested yeasts. Antagonists selective for mu, i.e., H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, delta, i.e., naltrindole, and kappa, i.e., norbinaltorphimine, opioid receptors completely blocked the respective receptor-selective agonist-induced suppression. These results suggest that the mu, delta and kappa opioid receptors can modulate macrophage function.

Polyarticular septic arthritis

Twenty-five cases of polyarticular septic arthritis (PASA) were observed in our department over a 13-year period. They accounted for 16.6% of all septic arthritis (15% on average in the literature). A male predominance was noted in our patients, as well as in the literature. The knee was the most frequent location followed by the elbow, shoulder, and hip, in varying order depending on the series. An average of 4 joints was involved. The causative microorganism was Staphylococcus aureus in 20/25 of our patients and in about 50% of published cases. Other frequently causative organisms were streptococci and gram-negative bacteria. Blood cultures and joint aspirations were positive in 19/22 and 23/25 of our cases, respectively. Other septic lesions were noted in 10/25 of our cases. Fever and severe leukocytosis were absent at admission in 5/25 (literature, 37%) and 10/25 of our 25 patients, respectively. The underlying disease was rheumatoid arthritis in 13/25, while 9 of the other patients had immunodepression caused by drugs or by concurrent illness. Typically, rheumatoid arthritis was long-standing and erosive, patients having ulcerated calluses on the feet. This skin source was also noted in 23/36 published cases of PASA in rheumatoid arthritis. Systemic lupus erythematosus was an uncommon disease in PASA, but its presence promoted gram-negative infection. Despite effective therapy with 2 antibiotics, 8/25 patients died, a prognosis that is equally severe in cases reported in the literature (30%) and one that has remained surprisingly stable over the last 40 years. For comparison, the death rate was only 4% in our patients with MASA. Factors contributing to a poor prognosis were age greater than 50 years, rheumatoid arthritis as an underlying disease, and disease of staphylococcal origin. Septic polyarthritis should be considered even when the clinical picture is not florid--when patients have low fever and normal white blood cell counts. Nor should the simultaneous involvement of distant joints rule out infection. Indeed, the frequency of underlying rheumatic disease and its treatment may further confuse the clinical presentation. Joints suspected of harboring infection should be aspirated, including those previously affected by the concurrent rheumatism.

Cytokine reversal of morphine-induced suppression of the antibody response

Female C3HeB/FeJ mice implanted with a morphine pellet exhibit a decreased primary antibody response in vitro as measured by the plaque-forming cell (PFC) assay. Suppression was detected at 24 hr following pellet implantation, was maximal at 48 hr and returned to normal by 120 hr. Splenocytes from control mice cocultured with splenocytes from morphine-treated mice (3:1 ratio) did not show a significant suppression, suggesting that morphine is not inducing the production of suppressor cells and/or factors. However, cells from morphine-treated mice cocultured with control cells (3:1) had a restored response. Further coculture experiments demonstrated that addition of adherent cells, but not nonadherent cells, restored the antibody response, suggesting that the macrophages from morphine-treated mice were deficient or defective. In vitro addition of interleukin (IL)-6, IL-1 beta or interferon-gamma (0.5-50 U/ml) attenuated the suppression of the PFC response in cells from morphine-treated mice, whereas higher doses (100 U/ml) restored completely the PFC response to control levels. Addition of IL-2, IL-4 or IL-5 to cultures from morphine-treated mice had little effect. Thus, morphine appears to cause immune suppression by reducing macrophage numbers or by interfering with the production or release of specific cytokines which are needed for a normal antibody response. Collectively, these data suggest that the macrophage is a key cellular target for the suppressive effects of morphine on the antibody response.

Pyrogenic doses of intracerebroventricular interleukin-1 did not induce analgesia in the rat hot-plate or cold-water tail-flick tests

There are a few reports in the literature that cytokines can induce analgesia (5, 6, 18). The present study sought to characterize the analgesic effects of intracerebroventricularly (icv) administered interleukin-1 (IL-1) and interferon-alpha (IFN-alpha) in rats. In the cold-water tail-flick test (CWT), latency to tail withdrawal from a -3 degrees C liquid was timed; in the hot-plate test (HP), latency to a rear paw lick or a jump from a 55 degrees C surface was measured. In some experiments, core body temperature was also monitored with a rectal thermistor. In the CWT, human recombinant (hr) IFN-alpha induced a small, statistically significant effect at just one dose (15,000 U icv), but no dose of hr-IL-1 alpha (250-1000 U icv) or hr-IL-1 beta (125-2000 U icv) induced a significant effect at any time point. On the other hand, dose-related increases in body temperature were observed after icv injection of both IL-1 alpha and IL-1 beta. The largest hyperthermic effect was a 1.7 (+/- 0.15) degrees C rise 120 min after administration of 1000 U IL-1 beta. In a second analgesic assay, the HP, IL-1 beta was ineffective as well. Since IL-1 alone did not induce analgesia, we tested its capacity to potentiate morphine analgesia. Morphine (5.0 and 10 micrograms, icv) induced analgesia in the CWT (32.7 and 61.8% maximum analgesia, respectively); however, there was no significant effect of IL-1 beta on morphine-induced analgesia. In summary, we failed to find an analgesic effect of IL-1, alone or in combination with morphine, at doses which clearly had a physiological effect; this is in contrast to the reports cited above.

Immunosuppressive effects of morphine on immune responses in mice

Implantation of a 75-mg morphine sulfate pellet subcutaneously into mice of different strains and sexes caused profound immunosuppression of their spleen cell primary in vitro antibody responses to sheep red blood cells. No sex differences were observed. In mice of the C3H lineage, naltrexone blocked the immunosuppression. In mice in the C57BL/6J lineage, naltrexone was ineffective in blocking the effects of morphine and was itself suppressive. In beige C57BL/6J bgJ/bgJ mice, placebo pellets were also suppressive. The mechanism of the morphine-induced immunosuppression was investigated in C3HeB/FeJ mice. Addition of normal splenic macrophages to in vitro cultures restored immune responses, as did IL-1, IL-6 and IFN-gamma, suggesting that morphine-induced immunosuppression is due to a deficit in macrophage function. Morphine pellet implantation induced splenic atrophy. Whether suppression is attributable to decreased macrophage numbers or to decreased functional capacity of individual macrophages is currently under investigation.

Morphine treatment in vitro or in vivo decreases phagocytic functions of murine macrophages

Studies were performed to compare in vitro and in vivo effects of morphine on the phagocytic function of murine peritoneal macrophages. Macrophage monolayers were incubated with Candida albicans for 30 min in the absence of autologous serum. Morphine added in vitro was found to decrease both the phagocytic activity (percent of phagocytic cells) and the phagocytic index (average number of ingested yeasts per cell) in a concentration-dependent manner, with maximal effects of 26% and 41%, respectively, at 10(-6) M. When morphine was administered in vivo via an implanted 75-mg pellet, there was a 22% decrease in phagocytic activity and a 40% decrease in the phagocytic index. Naltrexone completely blocked the effects of morphine both in vitro and in vivo. The results suggest that morphine is capable of interacting directly with opioid receptors on macrophages, resulting in a decrease in phagocytic function.

Effects of in vivo morphine treatment on antibody responses in C57BL/6 bgJ/bgJ (beige) mice

C57BL/6J bgJ/bgJ (beige) mice are less sensitive than other strains to the analgesic effects of morphine, although they have normal numbers of mu receptors. In the present study, beige mice and their normal littermates (beige+) were treated in vivo with morphine or the opioid antagonist, naltrexone and their primary in vitro antibody responses were assessed. Morphine treatment caused splenic atrophy and suppressed the primary in vitro antibody response in beige and beige+ mice. However, these effects were not blocked by naltrexone co-treatment. In these mouse strains, naltrexone decreased spleen size and antibody responses by itself, which may mask its ability to antagonize morphine. In beige mice, placebo pellet implantation suppressed the primary in vitro antibody response. Morphine did not cause a further suppression of the antibody response in beige mice compared to placebo. Because of this anomalous response to placebo treatment, the immunosuppressive effects of morphine on the antibody response/10(7) cells can not be attributed to a specific drug effect in this strain. However, when antibody responses were expressed on a per spleen basis, the overall capacity to respond to antigenic challenge was suppressed by morphine treatment.

Differential effects of morphine and naltrexone on the antibody response in various mouse strains

Morphine treatment has been shown to suppress several immunologic parameters. In this study, we examined the effects of morphine pellet implantation in vivo on the primary antibody response measured in vitro in various mouse strains. Effects of mouse strain and sex on morphine-induced suppression of the plaque-forming cell response, as well as spleen weight and mortality were determined. Morphine suppressed the primary antibody response in C3HeB/FeJ, C3H/HeJ and C57Bl/6 mice, while Balb/cByJ and the mu-receptor-deficient strain CxBk/ByJ mice were not affected. There was no difference in the response to morphine between male and female C3HeB/FeJ mice. Naltrexone reversed the morphine-induced suppression in the C3H strains, but not in C57Bl/6 mice. In addition, naltrexone caused significant mortality in Balb/cByJ mice. Spleen weight was decreased by morphine treatment in all the strains, but only the C3H strains were sensitive to the lethal effects of morphine. Thus, immune suppression did not correlate with splenic atrophy or mortality. The strain differences in response to chronic morphine and naltrexone treatment suggest that morphine may be acting through both opioid and non-classical opioid (e.g., not blocked by naltrexone) mechanisms.

Kinetics of allopurinol and its metabolite oxypurinol after oral administration of allopurinol alone or associated with benzbromarone in man. Simultaneous assay of hypoxanthine and xanthine by gas chromatography-mass spectrometry

Allopurinol, oxypurinol, hypoxanthine and xanthine were assayed simultaneously using a highly specific method combining gas chromatography and mass spectrometry. Two hypo-uricaemic prescriptions were compared: i) 300 mg of allopurinol (AL); and ii) 100 mg of allopurinol plus 20 mg of benzbromarone (AL + BZB). When administered acutely, their effects on blood uric acid levels were similar. Analysis of the pharmacokinetic parameters of allopurinol and its metabolite after each treatment showed dose-linearity for the metabolite but not for the drug itself. The area under the concentration time curve for allopurinol was 40.3 +/- 9.3 mumol l-1 h after AL, against 8.4 +/- 3.9 mumol-1 h after AL + BZB, while for oxypurinol it was 948.0 +/- 125.4 mumol l-1 h after AL and 285.2 +/- 77.9 mumol l-1 h after AL + BZB. The difference in dosage form may partly account for this difference, but the benzbromarone also seems to be involved. Its role on the blood uric acid lowering action of the drug association is complex. Although benzbromarone appreciably favors the elimination of oxypurinol, which should result in a weakening of its hypo-uricaemic action, this is offset by enhanced elimination of hypoxanthine and xanthine. Renal clearance of xanthine was significantly increased under AL + BZB (173.1 +/- 65.6 ml/min against 112.2 +/- 32.9 ml/min after AL). Similarly, blood xanthine levels were proportionately higher in the presence of benzbromarone. The action of the two agents may thus be synergistic and not antagonistic, a pharmacological justification for the therapeutic use of this drug association.

Effect of cyclosporine on 3-methylcholanthrene-induced carcinogenesis and immune responses in the rat

Cyclosporine A (CsA) was used to immunosuppress male Sprague-Dawley rats treated with the chemical carcinogen 3-methylcholanthrene (3MC). Rats treated with low doses of CsA (2.5 or 5 mg/kg) given 2 days prior to an injection of 3MC, and then daily for 2 weeks or twice weekly for 10 weeks did not develop tumors. Rats treated with 2.5 mg/kg CsA for 2 weeks beginning 5 days after a single 3MC injection had tumor incidence similar to rats treated with 3MC only. To further examine the effects of CsA on immune function, groups of rats were then treated with 2.5, 5, 10 or 20 mg/kg CsA daily for 14 days and immune function assessed by measuring delayed-type hypersensitivity (DTH), natural killer cell (NK) activity, and production of interleukin 2 (IL-2), interferon (IFN), prostaglandin E2 (PGE2) and specific IgG antibody. Natural killer cell cytotoxicity was enhanced and antibody production was suppressed in rats treated with all doses of CsA tested. Interleukin 2 production was elevated at the two lower doses, but antibody production, DTH reactions and synthesis of IL-2 and IFN were suppressed with the higher dose treatments (10, 20 mg/kg CsA). The enhanced NK activity seen in rats treated with the lower doses of CsA may be due to the increase in IL-2 production, while enhancement of NK activity at higher doses may be due to other mechanisms. The tumor data suggest that CsA does not prevent tumor formation in our chemical-induced model due to an increase in NK activity, since this enhancement was seen even when tumors did develop normally.

Effects of subchronic exposure of rats to 2-methoxyethanol or 2-butoxyethanol: thymic atrophy and immunotoxicity

Male Sprague-Dawley rats were exposed to either 2000 or 6000 ppm of 2-methoxyethanol (ME) or 2-butoxyethanol (BE) and females were exposed to either 1600 or 4800 ppm of these compounds in the drinking water for 21 days. Body weights were decreased in male rats exposed to the high doses of both chemicals, while body weights of females exposed to either dose of BE were decreased. Male and female rats exposed to either concentration of ME had a dose-related reduction in thymus weights. Testis weight was significantly lower in male rats exposed to the high dose of ME. Dose-related increases in natural killer (NK) cell cytotoxic activities and decreases in specific antibody production were observed in all rats treated with ME. Rats exposed to the low dose of BE also had enhanced NK cell activity. Splenocyte production of interferon-gamma was decreased in male rats exposed to either dose of ME and in females treated with the high dose of ME. Spleen cell numbers were reduced in males exposed to the high dose of ME and females given either dose of ME. It appears that the immune system is a sensitive target of ME but not BE. The effects of ME on immune function differ depending on the immune parameter assessed. Enhanced NK cell activity may partially explain the observations of others that certain glycol ethers have antitumor effects in vivo.

Effects of bromocriptine treatment on immune responses and 3-methylcholanthrene-induced tumorigenesis in rats

Seven-week-old male Sprague-Dawley rats were given a single injection of 1.5 mg of 3-methylcholanthrene (3MC) to induce in situ fibrosarcomas. The rats were also treated with the dopamine agonist bromocriptine (BCR) from two days prior to 14 days after 3MC treatment and again for 14 consecutive days beginning at week 5. Tumor incidence was markedly increased and latency decreased in BCR-3MC rats compared to 3MC controls. Natural killer (NK) cell cytotoxicity responses and production of interleukin 2 (IL2) was enhanced at two weeks in rats treated with only BCR. Natural killer cell activity was suppressed at two weeks in rats treated with only 3MC. This effect was reversed by BCR treatment. Rats treated with 3MC and BCR had suppressed NK cell responses and production of IL2 and interferon-gamma (IFN) at 12 weeks. In another study, rats injected with 1, 3 or 5 mg/kg BCR for 14 consecutive days had increased NK cell activity and IL2 production at all doses and increased IFN production at the two high doses. Antibody (IgG) responses to an injected antigen and delayed-type hypersensitivity reactions were not affected by BCR treatment. Animals treated with the two high doses of BCR had decreased serum prolactin (PRL) levels. Serum growth hormone (GH) concentrations were markedly increased in the group treated with 3 mg/kg BCR. These data suggest that BCR enhances 3MC-induced tumorigenesis. The mechanism of this effect is apparently not mediated by suppression of the immune system since BCR-treated rats had selectively enhanced immune function. Enhancement of immune responses by BCR has not been previously reported.

Plasma and blood assay of xanthine and hypoxanthine by gas chromatography-mass spectrometry: physiological variations in humans

Plasma and blood xanthine and hypoxanthine levels were assayed using a sensitive and specific method involving gas chromatography-mass spectrometry, associated with an optimized sample preparation procedure. Physiological variation was studied in 224 subjects with no purine metabolism disorders. An age dependency for both compounds was found, comparable with that known for uric acid. The mean plasma levels for the 224 subjects were 0.65 +/- 0.24 microM for xanthine and 1.65 +/- 0.78 microM for hypoxanthine. Corresponding mean blood levels were 0.59 +/- 0.21 microM for xanthine and 1.72 +/- 0.74 microM for hypoxanthine. Plasma and blood levels were significantly different, by ca. 10%. Rapid in vitro release of hypoxanthine from erythrocytes and continuation of intraerythrocytal metabolism lead to overestimation exceeding 10% within half an hour after sample blood collection. Hence samples must be deproteinized promptly. Blood can therefore be conveniently used for oxypurine assay instead of plasma when prompt spinning of samples is difficult to manage, as is usually encountered in clinical practice.

XeCl excimer laser coronary angioplasty: a convergence of favourable factors

The results of recent studies on the application of an XeCl laser to coronary angioplasty are presented. Several points are examined: the quality of the cut in human post-mortem artery, the cutting rates and threshold fluences in different media, the risks of carcinogenesis and thrombosis, and the transmission of suitable fluences in optical fibres. Recent human in vivo procedures are reported.

Hypophysectomy and growth hormone replacement effects on multiple immune responses in rats

Male Fischer 344 rats were hypophysectomized at 8 weeks of age. At 10 weeks of age, one group of these animals was treated with 40 micrograms of bovine somatotropin given daily sc for 13 days. A third group was sham-operated and injected daily with saline. All animals were sacrificed on Day 14 and multiple immune responses were assessed in each rat. Immune responses assayed included specific antibody production and delayed-type hypersensitivity (DTH) reactions to antigen, natural killer (NK) cell cytotoxicity, and production of interleukin 2 (IL2). Body and lymphoid organ weights, hematologic parameters, and spleen cell numbers were also recorded. Hypophysectomized (Hx) rats had reduced antibody synthesis, DTH reactions, NK cytotoxicity, IL2 (or IL4) production, body and organ weights, rbc counts, packed cell volumes, and hematocrits compared to sham-operated controls. White blood cell counts were elevated. Treatment of Hx animals with GH restored antibody and IL2 production and thymic weights and partially restored DTH reactions. These data indicate the pituitary is important in maintaining normal immune functions, and part of this effect may be via production of GH. It is postulated that GH may act through stimulation of IL2 (or IL4).

Safety and efficacy of once-daily carvedilol vs twice-daily labetalol in mild to moderate hypertension

A multicenter, randomized, double-blind, parallel-group trial of 8 weeks' duration was designed to compare the efficacy and safety of once-daily carvedilol with that of twice-daily labetalol in patients with essential hypertension. A total of 61 patients (13 women and 48 men) aged 26-64 years (mean +/- SEM = 49.6 +/- 1.3 years) were enrolled. All patients had mild to moderate hypertension, defined as diastolic blood pressure (DBP) of 95-114 mm Hg at the end of a 1- to 2-week single-blind placebo period. In all, 30 patients received carvedilol (25 mg once daily) and 31 received labetalol (200 mg twice daily). The initial dose could be doubled for both treatment groups at day 29 if the DBP was greater than 90 mmHg on days 28 and 29. Hemodynamic parameters, including supine and standing DBP, systolic blood pressure (SBP), and heart rate (HR), were measured and safety was evaluated at baseline and at days 14, 28, and 56 at the end of the dosing interval. In all, 3 patients on carvedilol and 4 patients on labetalol required upward dose titration after 1 month. At the end of the trial, 26 of 30 carvedilol-treated patients and 27 of 31 labetalol-treated patients (87% of each group) had a supine DBP of less than or equal to 90 mm Hg. On day 56, mean decreases in supine DBP, SBP, and HR in the carvedilol group were 18.5 and 23.4 mm Hg and 11 beats/min, respectively, from baseline values of 101.6 and 163.8 mm Hg and 80 beats/min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunotoxicity testing in the rat: an improved multiple assay model

Improvements have been made in the multiple assay model for assessing immunotoxicity in the rat which were previously reported (Exon, J.H., Koller, L.D., Talcott, P.A., O'Reilly, C.A. & Henningsen, G.M. (1986). Immunotoxicity testing: an economical multiple-assay approach. Fund. appl. Toxic., 7, 387-397). This improved model differs from the original in that: (1) the use of Freund's adjuvant has been eliminated from the antigen treatment schedule; (2) the same antigen, keyhole limpet hemocyanin (KLH), is used to induce both the delayed-type hypersensitivity (DTH) and specific antibody responses instead of separate antigens for each; and (3) the timing of antigen injections have been adjusted so that the DTH response is measured at the same time other assays are performed. These modifications have thus reduced the chance of non-specific stimulation of the immune system by Freund's adjuvant and eliminated possible antigen competition by using a single antigen to induce antibody synthesis and a DTH reaction. In addition, all immunoassays, including the DTH reaction, are performed at the same time, which allows for better comparison between responses and improves application to short-term repeated dose studies. Also, the immune parameters measured were shown to be sensitive to known immunosuppressants, cyclophosphamide and dexamethasone.

[Coronary endarterectomy using an excimer laser. Preliminary peroperative results]

From experimental and clinical experience, safe coronary angioplasty cannot be performed with CW lasers. The excimer laser does present a number of advantages in vitro: non-thermal ablation of plaques and a linear relationship between the number of pulses and the depth of the crater, so that tissue ablation is quantitatively predictable. A 308 nm, 20 ns pulse duration, 1 to 5 repetition rate laser was specifically designed for clinical application. During cardiopulmonary bypass prior to bypass grafting in 10 symptomatic patients, a 1 mm diameter core UV-tipped fiberoptic was introduced via the coronary arteriotomy and directed in contact with the coronary stenosis. Laser power was progressively increased until the stenosis or occlusion was recanalized. The quality of this angioplasty was controlled by calibration of he neo-lumen, cardioplegia solution flow through the lased segment, and 8th day coronary angiography. The laser treated coronary segments of the first 4 patients showed clearly parallel-lined patent neo-lumen despite competitive bypass graft flow. The main limitation of the method is that laser coronary recanalization is confined to the fiber core diameter. The authors conclude that: 1) excimer laser angioplasty is a safe and efficient intra-operative procedure; 2) the most critical problem for percutaneous laser angioplasty remains flexibility of the apparatus as the fiber diameter must be large enough to provide an adequate arterial neo-lumen.