Localization of chemoattractant receptors on Dictyostelium discoideum cells during aggregation and down-regulation

cAMP chemoattractant receptors on the surface of Dictyostelium discoideum cells are visualized by means of immunocytochemistry. Receptor antigen is virtually absent from growing cells and begins to accumulate after about 6 hr of starvation, concomitant with the increase in surface cAMP binding activity. In aggregating cells, the antigen is uniformly distributed over the cell surface. Persistent cAMP stimulation, which leads to down-regulation of cAMP binding activity, induces a striking rearrangement of receptor antigen into patches or internal vesicles. A similar patching of receptor antigen is observed during tight aggregate formation, when surface cAMP binding activity decreases. These observations indicate that receptor down-regulation involves receptor agglomeration and suggest that receptor down-regulation takes place in vivo, when tight aggregates are being formed.

Cyclic AMP-phosphodiesterase induces dedifferentiation of prespore cells in Dictyostelium discoideum slugs: evidence that cyclic AMP is the morphogenetic signal for prespore differentiation

We investigated whether cyclic AMP is an essential extracellular stimulus for the differentiation of prespore cells in slugs of D. discoideum. A local reduction of the extracellular cAMP level inside the slug was induced by implantation of cAMP-phosphodiesterase (cAMP-PDE)-coated spheres in intact slugs. This treatment caused the disappearance of prespore antigen in the vicinity of the sphere. A general reduction of extracellular cAMP levels in slugs, induced by submerging slugs in 0.25i.u.ml-1 cAMP-PDE, reduced the proportion of prespore cells from 66% to 15%, without affecting slug morphology. The cAMP-PDE-induced dedifferentiation of prespore cells was counteracted by cAMP and was not due to the production of the hydrolysis product 5′AMP, but to the reduction of extracellular cAMP levels. We conclude that extracellular cAMP is the major morphogenetic signal for the differentiation of prespore cells in the multicellular stages of D. discoideum development and we present a working hypothesis for the generation of the prestalk/prespore pattern during multicellular development.

Analysis of thromboelastogram on coagulation and fibrinolysis

Hartert's thromboelastography has been used in the diagnosis of abnormal blood clotting for more than 20 years. From a thromboelastogram three parameters are obtained, viz, the reaction time 'r', the rate of formation of fibrin clot 'k', the maximum elasticity of thrombus 'amax'. It is desirable, however, to know the equation that describes the thromboelastogram both in the period in which the complex modulus increases with time because of coagulation, and in the period in which the complex modulus decreases with time because of fibrinolysis. The parameters of the equation could then be used as a diagnostic criterion; yielding information on the mechanism of coagulation and fibrinolysis. Based on our experimental results on human blood in normal and abnormal subjects, we found that the complex modulus of thromboelastograms can be expressed by the sum of two terms, one describing the increase of the complex modulus during coagulation, G1 = G'1 Exp (-tau 1/t), the other describing the decrease of the complex modulus during fibrinolysis, G2 = G'2 Exp (-tau 2/(t-D) when t greater than D. G2 = 0 when t less than D. The compound complex modulus from coagulation to fibrinolysis is G = G1 - G2. Here t is the clotting time, and G'1, G'2, tau 1, tau 2, and D are five constants to be identified. These five constants can be used for diagnostic and prognostic purposes.

Cell cycle phase in Dictyostelium discoideum is correlated with the expression of cyclic AMP production, detection, and degradation. Involvement of cyclic AMP signaling in cell sorting

Cell cycle phase in Dictyostelium is correlated with a different preference for either spore or stalk differentiation. Cells which start development early in the cell cycle (E cells) exhibit a strong tendency to sort to the prestalk region of slugs, while late cell cycle cells (L cells) sort to the prespore region. We investigated the expression of the cAMP chemotactic system during development of synchronized E and L cells and found that E cells exhibit cAMP-binding activity, cell surface cAMP-phosphodiesterase (mPDE) activity, and the ability to relay cAMP signals at least 2 hr earlier and to higher levels than L cells. We hypothesize that E cells are prestalk sorters because they are the first to initiate aggregation centers and respond most effectively with chemotaxis and signal relay.

Lithium respecifies cyclic AMP-induced cell-type specific gene expression in Dictyostelium

We investigated the effect of LiCl on pattern formation and cAMP-regulated gene expression in Dictyostelium discoideum. In intact slugs, 5 mM LiCl induces an almost complete redifferentiation of prespore into prestalk cells. We found that LiCl acts by interfering with the transduction of extracellular cAMP to cell-type-specific gene expression; LiCl inhibits the induction of prespore-specific gene expression by cAMP, while it promotes the induction of prestalk-associated gene expression by cAMP. Our results indicate that two divergent pathways transduce the extracellular cAMP signal to, respectively, prestalk and prespore gene expression.

Evidence for intermediate filaments in squirrelfish erythrophores of Holocentrus ascensionus (Rufus)

We have documented the presence of intermediate filaments (IF) in cultured erythrophores of the squirrelfish Holocentrus ascensionus (Rufus). SDS-PAGE and Western blots with monoclonal antibodies T11 and R12 demonstrated that isolated IF consisted of a pair of polypeptides of 54 and 52 kDa. Immunofluorescent studies revealed that the two proteins formed prominent radially oriented IF networks in erythrophores. Immunoelectron microscopic studies showed that the IF were distributed in a "spider-web"-like network of filaments which occasionally intersected with the microtubule surfaces. The IF proteins also were found in fish iridiphores but not in fish epithelial cells which cocultured with the chromatophores.

[Value of prophylactic irradiation to supraclavicular areas in small cell lung carcinoma--analysis of 104 patients]

A series of 104 patients with limited small cell lung carcinoma was treated by combination of chemotherapy and radiotherapy from August 1975 to July 1981. 104 patients were divided into three groups: prophylactic irradiation to supraclavicular areas (14 patients), non-prophylactic group (72 patients), non-prophylactic irradiation with positive supraclavicular lymph node metastasis after the treatment (18 patients). The 5 year survival rates of the three groups were 14%, 6% and 0%. Distant metastasis rates after the treatment were 36%, 52% and 61%, respectively. The supraclavicular lymph node metastasis rate after the treatment was higher in patients with intra-thoracic lymph node metastasis before the treatment (25%) than in those without this metastasis (0%). It is suggested that, for small cell lung cancer patients, especially with intra-thoracic lymph node metastasis before the treatment, prophylactic irradiation to the supraclavicular areas be valuable.

Immunofluorescent studies of the anti-microtubule effects of the anti-cancer drug estramustine

Immunofluorescent studies in human prostatic carcinoma cells (DU 145) and cultured squirrel fish epithelial cells (a non-cancer cell) revealed that estramustine, a conjugate of estradiol and nor-nitrogen mustard, possessed microtubule disassembly properties. Sixty microM estramustine produced disassembly at both the proximal and distal ends of microtubules, producing short pieces of less than 2 microM which were "wavy" and oriented in a random manner. With increased time of drug exposure these short microtubules disappeared, to be accompanied by a gradual disassembly of a small population of longer microtubules (greater than 7-8 microM). In dividing DU 145 cells it was possible to show a different degree of sensitivity of specific microtubule-containing cellular structures. In mitotic figures the asters were most sensitive and disappeared completely following exposure to estramustine. These were followed by the "pole-to-pole" and "chromosomal" fibers. In cytokinesis, the intercellular fibers between daughter cells were comparatively resistant to the drug. Estramustine did not induce disassembly of the vimentin filaments in non-dividing or dividing cells but did cause their collapse around the nucleus or the mitotic apparatus. These data suggest that specific microtubules have differing sensitivity to estramustine.

Diagnosis of tertian malaria by enzyme-linked immunosorbent assay

A method of ELISA diagnosis of tertian malaria based on detecting Plasmodium vivax antigen in red blood cells (RBC) was developed, using 0.16 ml of packed, washed, and sonicated RBC. 68 blood samples from tertian malaria cases were examined; 67 (98.5%) were positive. 104 normal persons were all negative by this test. The lowest parasite number detected was 3 parasites/10(5) RBC on a thin film, or 1-2 parasites per thick film of usual size.

Polarized pigment granule transport occurs in the absence of microtubules in squirrelfish erythrophores: studies of the effects of estramustine

We have re-examined the involvement of microtubules in the process of pigment granule transport in squirrelfish erythrophores in situ (i.e. on scales). Light-microscopic studies revealed that following exposure to 5 microM-nocodazole for 1 h at 4 degrees C erythrophores retained an ability to aggregate and disperse their pigment uniformly, though at reduced rates. Serial thick-section stereo high-voltage electron-microscopic studies showed that the entire microtubule population was removed by drug treatment and that the microtubules were not reassembled as a result of pigment translocation processes in the presence of reduced levels of nocodazole (0.4 microM). Immunofluorescence microscopic studies confirmed that nocodazole (0.5-1 microM) produced rapid disassembly of the microtubules. Whole-mount electron-microscopic studies showed that the pigment granules were suspended in a cross-linking network of 3–10 nm filaments, which appeared to support ordered pigment transport in situ in the absence of microtubules. Drug inhibition studies showed that micromolar levels of estramustine, a novel anti-MAPs (microtubule-associated proteins) drug, reversibly inhibited pigment transport. The results suggest that an estramustine-sensitive cytomatrix component might produce polarized pigment transport in intact erythrophores.

Fractal model of ion-channel kinetics

Markov models with discrete states, such as closed in equilibrium with closed in equilibrium with open have been widely used to model the kinetics of ion channels in the cell membrane. In these models the transition probabilities per unit time (the kinetic rate constants) are independent of the time scale on which they are measured. However, in many physical systems, a property, L, depends on the scale, epsilon, at which it is measured such that L(epsilon) alpha epsilon 1-D where D is the fractal dimension. Such systems are said to be 'fractal'. Based on the assumption that the kinetic rates are given by k(t) alpha t1-D we derive a fractal model of ion-channel kinetics. This fractal model has fewer adjustable parameters, is more consistent with the dynamics of protein conformations, and fits the single-channel recordings from the corneal endothelium better than the discrete-state Markov model.

[Preliminary evaluation of the combination of Chinese herbal medicine (destagnation) and radiotherapy for esophageal cancer]

From May 1973 to March 1979, a prospective randomized clinical trial on 425 patients with esophageal cancer was conducted. 194 patients were allotted into the destagnation plus radiotherapy group, the other 231 into radiotherapy only group. The result shows that the combination of destagnation and radiotherapy does not give a result superior to radiotherapy alone. However, destagnation does not increase either hematogenous, lymphatic metastasis, perforation or hemorrhea of the esophageal cancer.

[Carcinoma of esophagus treated by 8MV X-ray and checked by simulator]

From January 1, 1978 to December 31, 1983, 570 patients with carcinoma of esophagus were treated by 8 MV X-ray and checked by the Philips simulator. In order to assess their value, a series of 3,798 patients reported previously was used for comparison. To further evaluate the effect of 8 MV X-ray and simulator separately, a series of 154 patients was treatment by non-8 MV X-ray during the same period. The results showed that the 1 and 3 year survival rates of 8 MV X-ray series were better than the 3,798 series (P less than 0.01). It means that after the use of simulator and 8 MV X-ray the survival rates were improved. As compared to the radiation other than 8 MV X-ray, there was no difference between 8 MV X-ray and non-8 MV X-ray series, which means that the improvement may have been due to the better localization by the simulator. Having more importance, no radiation myelitis was found after the use of simulator. The sex, age, length, location, X-ray type, NSD and causes of failure were compared in these groups.

[Superior sulcus cancer of the lung--report on 45 patients]

From 1960 to 1980, 45 patients with superior sulcus cancer of the lung were seen in our hospital. 39 were male and 6 were female. The youngest was 28 years old and the eldest was 75. The presenting symptoms and signs were back and shoulder pain in 32 patients, compression of the brachial plexus in 17, Horner's syndrome in 12, supraclavicular mass in 11, superior cava vena obstruction in 4, shadow in the apex in 45, destruction of the rib in 19 (10 in the second rib), destruction of the adjacent vertebra in 8 (5 in T3) and destruction of the clavicle in 1. In 18 patients proved by pathology and cytology, 8 were adenocarcinoma, 3 squamous cell carcinoma, 3 undifferentiated and 4 unclassified carcinoma. 27 patients were diagnosed by X-ray films. 40 patients were admitted for treatment. 3 recieved chemotherapy alone and all of them died in one year. Of the 6 treated by radiation plus chemotherapy, 3 survived for one year but all died in two years. 2 were treated by radiation plus operation and none survived for more than 3 years. 29 were treated by radiation only. The 1, 3 and 5 year survival rates were 51%, 13.7% and 6.9%. Destruction of the rib or the adjacent vertebral body was irrelative to the prognosis but the presence of supraclavicular mass reduced the survival rate. Cause of death was local recurrence in 48% (13/27) and distant metastasis in 48% (13/27). The authors suggest that radical en bloc resection together with radiation the worth further study.

Occult gastric cancer manifested by progressive shortness of breath in a young adult

We have reported a case of occult, diffuse gastric cancer in a young adult with progressive shortness of breath and bilateral pulmonary interstitial infiltrates. Progressive shortness of breath may be the first or only manifestation of occult gastric cancer caused by either lymphangitic carcinomatosis or microscopic tumor emboli to the lungs. Widespread recognition of this syndrome, a high index of suspicion, and prompt lung biopsy are necessary to make the correct diagnosis. With progress in chemotherapy for malignant diseases, early diagnosis and specific treatment may improve the prognosis of this condition.

Activities of cerebral dihydropteridine reductase and tyrosine hydroxylase in chronic uremia in rats

The effect of chronic uremia on activities of cerebral dihydropteridine reductase (DHPR) and tyrosine hydroxylase (TH) and content of norepinephrine and dopamine was investigated in the male Sprague-Dawley rats. The uremic animals were fed diets containing either 8% or 18% casein ad libitum, and sham-operated pair-fed and ad libitum fed animals were used as controls. There were no significant differences in TH activity between the groups fed the two levels of protein. Uremic rats had lower activity of TH than pair-fed controls, and pair-fed controls had lower activity than ad libitum-fed animals. DHPR activity and norepinephrine and dopamine content did not differ among the groups. Our study suggests that the chronic uremic condition or restricted feeding causes a decrease in brain TH activity which is not mediated by decreased DHPR activity. Further, this decreased enzyme activity does not result in depressed catecholamine content, indicating the presence of a highly regulated mechanism controlling catecholamine levels.

Changes in psychophysiological and conditioning variables during chlormethiazole-medicated and unmedicated ethanol withdrawal: preliminary report

Autonomic lability during ethanol withdrawal in chlormethiazole-medicated and unmedicated groups was investigated using electrodermal measures. Vulnerability to Pavlovian aversive conditioning was also assessed. Ethanol withdrawal was associated with increased autonomic arousal and aversive conditioning, suggesting an increased risk of phobia acquisition. Chlormethiazole administered during ethanol withdrawal may protect against such developments.

The cytomatrix regulates "resolute" transport in erythrophores

Light microscopic studies have indicated that most microtubule-directed transport is either saltatory or resolute in nature. The latter form of transport is an intriguing phenomenon, because it commonly involves the unidirectional bulk motion of an organelle(s) such as chromosomes in dividing cells or pigment granules in chromatophores. We have investigated the ultrastructural and biochemical basis for the resolute transport of pigment in chromatophores. Light and EM studies of erythrophores in situ have clearly shown that when the microtubules were completely removed with nocodazole, resolute transport continued and was stimulated by aggregating and dispersing agents. Light and electron microscopic studies of cultured erythrophores permeabilized with digitonin indicated that resolute motion was produced by a cytomatrix of 3 to 7 nm filaments. Immunofluorescent analysis with several monoclonal antibodies raised against MAP-2 further demonstrated that MAP-2 was an important component of the contractile cytomatrix that powers pigment aggregation and dispersion. We conclude that a microtubule-associated cytomatrix normally produces resolute pigment transport in chromatophores.

Interactions between adenosine and oscillatory cAMP signaling regulate size and pattern in Dictyostelium

We present evidence for the hypothesis that in multicellular structures of Dictyostelium, production of adenosine by hydrolysis of cAMP near the tip region prevents both generation of competing tips and differentiation of prespore cells near the tip, and thus establishes a "prestalk" region. We demonstrate that adenosine affects the immunological prespore specific staining pattern in slugs in a manner opposite to cAMP:cAMP induces an increase of prespore antigen; adenosine induces a decrease. When endogenous adenosine is removed from slugs, prespore vacuoles are synthesized throughout the prestalk region. Adenosine was found to inhibit the induction of prespore differentiation by cAMP in an apparently competitive manner. It was also found that adenosine specifically increased the amount of tissue controlled by one tip, probably by inhibiting generation of competing oscillators. Removing endogenous adenosine from slugs resulted in a decrease of tip dominance.

Phorbol 12,13-dibutyrate increases tyrosine hydroxylase activity in the superior cervical ganglion of the rat

Phorbol 12,13-dibutyrate (PDBu) increased the production of 3,4-dihydroxyphenylalanine (DOPA) in the superior cervical ganglion of the rat. This effect occurred without a detectable lag and persisted for at least 90 min of incubation. The action of PDBu was half-maximal at a concentration of approximately 0.1 microM; at high concentrations, PDBu produced about a twofold increase in DOPA accumulation. PDBu increased DOPA production in decentralized ganglia and in ganglia incubated in a Ca2+-free medium. The action of PDBu was additive with the actions of dimethylphenylpiperazinium, muscarine, and 8-Br-cyclic AMP, all of which also increase DOPA accumulation, and was not inhibited by the cholinergic antagonists hexamethonium (3 mM) and atropine (6 microM). Finally, PDBu did not increase the content of cyclic AMP in the ganglion. Thus, the action of PDBu does not appear to be mediated by the release of neurotransmitters from preganglionic nerve terminals, by the stimulation of cholinergic receptors in the ganglion, or by an increase in ganglionic cyclic AMP. PDBu also increased the incorporation of 32Pi into tyrosine hydroxylase. PDBu activates protein kinase C, which in turn may phosphorylate tyrosine hydroxylase and increase the rate of DOPA synthesis in the ganglion.

Effects of butylated hydroxyanisole on the tumorigenicity and metabolism of N-nitrosodimethylamine and N-nitrosopyrrolidine in A/J mice

Female A/J mice were maintained on NIH-07 diet or on NIH-07 diet containing butylated hydroxyanisole (BHA, a mixture of 2- and 3-tert-butyl-4-hydroxyanisole), 5 mg/g, for 1 week prior to and during 10 weeks of treatment with N-nitrosodimethylamine (NDMA) or N-nitrosopyrrolidine (NPYR), administered in the drinking water. Twenty weeks after nitrosamine treatment ended, mice were sacrificed and lung adenomas were counted. BHA inhibited NDMA tumorigenesis but enhanced NPYR tumorigenesis. Treatment of A/J mice for three weeks with BHA (5 mg/g) added to semisynthetic diet increased whole lung microsomal alpha-hydroxylation of NDMA and NPYR, as measured by aldehyde production, and increased lung and hepatic glutathione-S-transferase activities. No evidence was found for formation of S-methylglutathione in incubations with NDMA and hepatic supernatants obtained from BHA treated or control mice. Four h after gavage of NDMA, levels of 7-methylguanine in the lung DNA of mice treated with BHA were higher than in the lung DNA of control mice, but levels of O6-methylguanine in the two groups were the same. The results of this study indicate that BHA treatment increases the microsomal metabolic alpha hydroxylation of both NDMA and NPYR, but has differential effects on their tumorigenic activities.

Intramucosal gastric carcinoma in a patient with familial polyposis coli

Upper gastrointestinal polyps commonly occur in patients with familial polyposis coli; but the occurrence of gastric carcinoma is very rare in this disorder. We report a case of intramucosal gastric carcinoma in a patient with familial polyposis coli and multiple gastrointestinal adenomatous polyps.

Endoscopic sclerotherapy for bleeding rectal varices: a case report

Rectal varices are not hemorrhoids and they are dilated submucosal veins connecting the middle and inferior hemorrhoidal veins. These rectal varices may occur in patients with portal hypertension because of the formation of portosystemic shunts. Like esophageal varices, the rectal varices may also bleed massively. Herein we report a case of such bleeding which was successfully controlled with endoscopic sclerotherapy to the rectal varices.

De novo carcinoma of the rectum: a case report

There is strong evidence in the literature to suggest that most of the colorectal carcinomas arise from adenomatous polyps. Yet, rare carcinomas may arise de novo and we are reporting such a case of intramucosal rectal carcinoma occurring in a 47-year-old healthy man.

Metastatic squamous cell carcinoma from the esophagus occurring as small bowel obstruction

Metastatic tumors of the small bowel from extra-abdominal sites are rare. The primary tumors that have been reported are malignant melanoma, breast cancer, bronchogenic carcinoma, embryonal myosarcoma, and seminoma. We have presented a case of small bowel obstruction due to metastasis from esophageal cancer.

Merkel cell tumor with liver metastases: presentation as fulminant hepatic failure

This report demonstrates that hepatic metastases can present with fulminant hepatic failure and that liver enzyme abnormalities may not become prominent until there has been massive replacement of the liver. The CT scan of liver may not demonstrate diffuse liver metastases as seen in this patient. Merkel cell tumor or trabecular neuroendocrine skin tumor is a previously unreported cause for the development of the syndrome of hepatic failure due to liver metastases.

cAMP induces a transient elevation of cGMP levels during early culmination of Dictyostelium minutum

Oscillatory cAMP signals very likely organize the cell movement which leads to fruiting body construction in Dictyostelium minutum [Schaap, P., Konijn, T.M. and Van Haastert, P.J.M.: Proc. Natl. Acad. Sci. USA 81, 2122-2126 (1984)]. Stimulation with cAMP induces a transient elevation of cGMP in cells at the early culmination stage, which peaks at 12-18 s. A half maximal cGMP response is induced by 10(-7) M cAMP and saturation of the response is reached at 10(-5) M cAMP. No cGMP accumulation was induced by stimulation of vegetative or aggregative cells of D. minutum by cAMP. Since the transient increase of cGMP is most likely involved in the transduction of chemotactic signals, our results indicate that cAMP signals organize fruiting body formation by inducing chemotaxis inside the aggregate.

EEG effects of subcutaneous and intracerebroventricular injections of arginine vasopressin in the rat

Several studies have suggested that arginine vasopressin (AVP) may act centrally as a neurohormone or neuromodulator to produce electrophysiological and behavioral effects. However, there are few reports of EEG effects of AVP in unanesthetized, behaving animals. In the present study the EEG effects of "behaviorally relevant" subcutaneous (SC) doses of AVP (6 micrograms/kg) known to raise blood pressure were compared to "behaviorally relevant" intracerebroventricular (ICV) doses (0.1-1.0 ng) and multiple "toxic" ICV doses (1.0 microgram) of AVP. Central injections of toxic doses of AVP produced behavioral arrest, bodily barrel rolling, and EEG slowing, but did not induce electrographic signs of seizure activity. Comparison of the spectral characteristics of the EEG revealed some similarities in the distribution of power between SC and the 1.0 ng ICV dose; whereas ICV doses of 0.1 and 0.5 ng produced power distributions that were different from those seen following saline or SC doses of AVP. The similarities in EEG activity between SC injections and the 1.0 ng ICV dose suggest a common brain state may be induced by the two routes of administration in those dose ranges.

The possible involvement of oscillatory cAMP signaling in multicellular morphogenesis of the cellular slime molds

The involvement of pulsatile chemoattractant emission and signal relay in aggregation and multicellular morphogenesis of a variety of cellular slime mold species was investigated. The species differ from each other in the developmental stage when pulsatile signaling first becomes evident. In D. discoideum, D. mucoroides, and D. purpureum pulsatile signal emission starts in the preaggregative field. In D. vinaceo-fuscum, D. mexicanum, P. violaceum, and P. pallidum the aggregation centers shifts from continuous to pulsatile secretion of chemoattractant during the aggregation process. In D. minutum pulsatile signaling starts after the completion of aggregation and slightly before the onset of culmination. Tip formation is a consequence of continued attraction of amoebae inside the aggregate to the center of signal emission. The occurrence of pulsatile signaling at an early stage of development is correlated with the capacity of the tip (signaling center) to organize a relatively large number of cells into a single fruiting body. Several lines of evidence suggest that cAMP is probably involved in the coordination of morphogenetic movement in the multicellular stage of all investigated species.

Synaptic connections from large muscle afferents to the motoneurons of various leg muscles in man

Cross-correlations between stimuli delivered to peripheral nerves and the discharges of single, voluntarily activated, motor units can provide information about facilitatory and inhibitory projections to single spinal motoneurons in man. The projection frequency, under the given circumstances, of a facilitatory or inhibitory pathway can be obtained from the proportion of the sampled motor units of a given muscle showing the facilitatory or inhibitory effect. Deductions about the shape and relative amplitude of the underlying post-synaptic potentials can be made from the profile of the changes in firing probability. This technique has been used to explore the projections of low threshold muscle afferents to motoneurons of various leg muscles in man. Homonymous facilitation was demonstrated to all the sampled motor units of soleus (SOL), medial gastrocnemius (MG), tibialis anterior (TA) and vastus medialis (VM) and is presumed to represent the effects of the composite muscle spindle group Ia EPSP. Heteronymous facilitation was demonstrated between certain synergists. The projection frequency was less and the magnitude of the change in firing probability was smaller than for homonymous facilitation. SOL motoneurons, however, were not facilitated from low threshold afferents in the medial gastrocnemius nerve. Reciprocal inhibition was demonstrated between certain antagonists. The majority of the sampled motor units of SOL, however, were facilitated from low threshold afferents in the common peroneal nerve. The threshold for this facilitation was higher than for the homonymous facilitation elicited from this nerve and thus a different class of afferents and/or intercalated interneurons may be involved. There are projections across the knee joint in man. Motor units in vastus medialis (VM) were facilitated from low threshold afferents in the common peroneal nerve. It is likely that these reflex connections, which differ from those in other species, reflect the functional relationships between various lower limb muscles in man.

Microtubule polarity and the direction of pigment transport reverse simultaneously in surgically severed melanophore arms

The transport of pigment through the long cytoplasmic extensions (arms) of teleost melanophores is a microtubule-dependent event. We have severed the arms from melanophores to test whether microtubules isolated from the centrosome maintain their original polarity and disposition. In addition, we have tested whether arms containing microtubules of mixed polarities alter the direction of pigment transport. We find that microtubules within severed arms eventually change their polarity and reorganize from the arm center as if to form a new minicell. Concomitant with this change is a reversal in the direction of pigment transport.

EEG spectra following phenytoin infusion in seizure patients

Diphenylhydantoin (DPH) kinetics were studied in five male patients with poorly controlled seizures. EEG recordings were taken on four of the patients immediately prior to and 30 minutes following a 60 minute i.v. infusion of phenytoin sodium. Mean phenytoin levels following post-infusion EEG recordings were 17.1 mg/L. Spectral analysis revealed that phenytoin produced a decrease in the variance of EEG spectral power as a function of time in frequencies between 8-18 Hz. This decrease in the variance of the time series of EEG spectra suggests increased EEG stability and may represent an electrographic marker of the anticonvulsant action of phenytoin.

GTP cyclohydrolase I deficiency, a new enzyme defect causing hyperphenylalaninemia with neopterin, biopterin, dopamine, and serotonin deficiencies and muscular hypotonia

A 4-year-old patient is described with hyperphenylalaninemia, severe retardation in development, severe muscular hypotonia of the trunk and hypertonia of the extremities, convulsions, and frequent episodes of hyperthermia without infections. Urinary excretion of neopterin, biopterin, pterin, isoxanthopterin, dopamine, and serotonin was very low, although the relative proportions of pterins were normal. In lumbar cerebrospinal fluid, homovanillic acid, 5-hydroxyindoleacetic acid, neopterin and biopterin were low. Oral administration of L-erythro tetrahydrobiopterin normalized the elevated serum phenylalanine within 4 h, serum tyrosine was increased briefly and serum alanine and glutamic acid for a longer time. Urinary dopamine and serotonin excretion were also increased. Administration of an equivalent dose of D-erythro tetrahydroneopterin was ineffective and demonstrated that this compound is not a cofactor in vivo and cannot be transformed into an active cofactor. GTP cyclohydrolase I activity was not detectable in liver biopsies from the patient. The presence of an endogenous inhibitor in the patient's liver was excluded. This is the first case of a new variant of hyperphenylalaninemia in which the formation of dihydroneopterin triphosphate and its pterin metabolites in liver is markedly diminished. Normal activities of xanthine oxidase and sulfite oxidase were apparent since uric acid levels were normal and no increase in hypoxanthine, xanthine, and S-sulfocysteine concentrations could be observed in urine. It is concluded that the molybdenum cofactor of these enzymes may not be derived from dihydroneopterin triphosphate in man. Also, since no gross abnormalities in the patient's immune system could be found, it seems unlikely that dihydroneopterin triphosphate metabolites, such as neopterin, participate actively in immunological processes, as postulated by others. See Note added in proof.

Intrageneric and intergeneric transfer of Branhamella catarrhalis beta-lactamase production

Intrageneric and intergeneric conjugational transfer of beta-lactamase production to a Branhamella catarrhalis recipient is described. The branhamella donor strains were fresh isolates subcultured onto penicillin-containing media directly from the primary plates. A beta-lactamase positive Moraxella nonliquefaciens served as donor in the intergeneric matings. The substrate profiles of the branhamella and moraxella enzymes were indistinguishable as determined by biological assays. Excessive endonuclease activity did not permit a conclusive characterization of isolated extrachromosomal DNA from the branhamella donors.

Corticotropin releasing factor produces increases in brain excitability and convulsive seizures in rats

Corticotropin releasing factor (CRF) is a 41-residue peptide, capable of stimulating the secretion of corticotropin (ACTH)-like and beta-endorphin-like immunoreactivity from the adenohypophysis. Low doses of CRF (0.0015-0.15 nM) given intracerebroventricularly (i.c.v.) produced changes in electrographic activity suggestive of increased arousal. Higher doses of CRF (1.5-3.75 nM) induced, over a period of 3-7 h, electrographic and behavioral signs of seizure activity indistinguishable from those which occur following electrical 'kindling' of the amygdala.