Monocular deprivation in humans: a study of identical twins

Ultrasonic axial length measurements and psychophysical vernier acuity thresholds were determined for a pair of identical human twins, one of whom had been monocularly deprived since birth with a congenital lens opacity. Axial lengths of both eyes in the normal twin and the nondeprived eye in the other twin differed by less than 0.2 mm, whereas the axial measurement of the deprived eye was approximately 2.0 mm longer. Monocular vernier acuity thresholds in the nondeprived eye of the one twin were not significantly different from those obtained in the normal twin. Our findings are consistent with previous reports of increased axial length after monocular deprivation deprivation but do not support the concept of enhanced vernier acuity in the nondeprived eye of monocularly deprived humans.

Cholinergic mechanism in the large cat cerebral artery

The isolated cat cerebral arteries (basilar, middle cerebral, anterior cerebral, and internal carotid) were studied in vitro. ACh at low concentration (3 x 10(-8) to 3 x 10(-6) M) induced relaxation, and at high concentration (10(-5) to 3 x 10(-3) M) induced constriction of the arteries with endothelial cells. In contrast, concentration of any magnitude (10(-6) to 3 x 10(-3) M) induced constriction exclusively in arteries without endothelium. Atropine (3 x 10(-6) to 3 x 10(-5) M) blocked and physostigmine (3 x 10(-6) M) potentiated both ACh-induced relaxation and constriction. These results suggest that the relaxation induced by exogenous ACh is solely dependent on the endothelial cells and that the primary effect of the direct action of ACh on the smooth muscle cells is constriction. Transmural nerve stimulation (TNS) induced a frequency-dependent relaxation in the arteries with or without endothelium. Neither atropine nor physostigmine affected the TNS-induced dilator response in either preparation. This, together with the wide separation between the nerve and endothelium in the vessel wall, suggests that ACh is not involved in TNS-induced vasodilation. Furthermore, the TNS-induced relaxation at any frequency is not smaller but greater in the arteries without endothelial cells than in those with endothelial cells. Blockade of the TNS-induced vasodilation by tetrodotoxin (TTX) or cold storage denervation did not prevent the arteries from relaxing in response to ACh or methacholine (MCh). It is suggested that the TNS-induced vasodilation is independent of the endothelial cells and that the vasodilation is due to the direct action of a yet-to-be identified dilator transmitter on the smooth muscle cells. Results of the present study support our previous finding that, in the cat cerebral artery. ACh is more likely to be a constrictor transmitter than a dilator transmitter.

Gonococci with mutations to low-level penicillin resistance exhibit increased sensitivity to the oxygen-independent bactericidal activity of human polymorphonuclear leukocyte granule extracts

Gonococci which cause disseminated gonococcal infection are nearly always highly penicillin sensitive, in contrast to many isolates causing uncomplicated gonorrhea. We questioned whether any of the known chromosomal mutations to low-level penicillin resistance might adversely affect virulence. The penA2 locus is known to result in low-level resistance to penicillins, whereas mtr-2 results in nonspecific resistance to a variety of antimicrobial agents. We found that the penA2 and mtr-2 mutations each markedly increased sensitivity of strain FA19 to oxygen-independent killing by human polymorphonuclear leukocyte mixed or isolated azurophilic granule extracts. The penA2 and mtr-2 mutations had no effect on sensitivity to serum antibody and complement. Isogenic opaque or transparent variants of several strains of Neisseria gonorrhoeae were equally resistant to human polymorphonuclear leukocyte mixed granule extract bactericidal systems. There were also no differences in susceptibility of piliated type 1 and nonpiliated type 4 variants to human polymorphonuclear leukocyte mixed granule extracts. Since the penA2 and mtr-2 loci are known to increase the degree of cross-linking of cell wall peptidoglycan, the structure of peptidoglycan apparently affects sensitivity to killing by one or more polymorphonuclear leukocyte azurophilic granule extract bactericidal systems. These observations might explain why gonococci with mutations similar to penA2 and mtr-2 are almost never isolated from patients with disseminated gonococcal infection.

Effect of superior cervical ganglionectomy on the sensitivity of rabbit ear artery and cerebral arteries of rabbit and cat to vasoactive agents

The effect of sympathetic denervation on the sensitivity of the rabbit ear and basilar arteries and the cat middle cerebral artery to vasoactive agents was examined in relation to the functional significance of the innervation. Fourteen days after superior cervical ganglionectomy, the catecholamine fluorescence disappeared and the norepinephrine content drastically decreased and transmural nerve stimulation ceased to elicit any response in all these arteries. In the rabbit ear artery, denervation resulted in a significant leftward shift of dose-response curves for norepinephrine (8.2-fold), serotonin (7.7-fold), histamine (2.9-fold) and potassium (1.2-fold). In contrast, there was no significant shift of dose-response curves to these drugs in the rabbit basilar and cat middle cerebral arteries. These results indicate that after chronic superior cervical ganglionectomy, postjunctional supersensitivity developed in the rabbit ear artery, but no pre- or postjunctional supersensitivity occurred in the rabbit basilar and cat middle cerebral arteries. The difference may be in part attributable to the reported closer synaptic cleft distance of the sympathetic nerve terminals in the ear than in the cerebral arteries examined. These results further suggest that the sympathetic adrenergic nerve exerts a tonic influence over the rabbit ear artery, but little or none in normal cerebral blood vessels.

Recurrent bacterial meningitis associated with C8 and IgA deficiency

A patient with recurrent bacterial meningitis who lacked circulating C8, serum IgA, and secretory IgA is reported. The combined absence of C8 and IgA deficiency has not been previously noted. Although the association of disseminated neisserial infection and absence of the terminal complement components is now well established, the deficiency of bactericidal capability as well as mucosal humoral defense may have been additive in predisposing the patient to recurrent meningitis. The pedigree was uninformative regarding possible linkage of these two uncommon genetic errors.

Ultrastructural distribution of vasodilator and constrictor nerves in cat cerebral arteries

This study examined the ultrastructural distribution of agranular vesicle-containing nerve (AVN) and granular vesicle-containing nerve (GVN) in cat cerebral blood vessels fixed in KMnO4. The percentages of the AVN and GVN throughout the adventitial layer in the basilar, middle cerebral, and anterior cerebral arteries were 63.4 and 36.7, 53.9 and 46.1, and 60.2 and 39.8, respectively. The AVN in the cat basilar artery is approximately 37 times denser than that in the rabbit basilar artery. This morphological result, in correlation with the previous pharmacological findings, provides indirect evidence that the AVN are the dilator nerves. The lack of neurogenic vasoconstriction in the cat basilar, middle cerebral, and anterior cerebral arteries may be attributable in part to a combination of denser dilator than constrictor nerves, a possible closer synaptic cleft distance for dilator than for constrictor nerves, and the reported insensitivity of the postsynaptic alpha-receptors. The small pial vessels (branches of the middle cerebral arteries), on the other hand, contain predominantly GVN (88%), suggesting that dilator nerves relative to constrictor nerves decrease as the size of the cerebral blood vessels becomes smaller. Furthermore, the synaptic cleft distance is found not parallel to the outer diameter of the artery. Thus, the results of this study indicate that the neurogenic control of brain circulation varies with brain region, lending further support to the theory that the dual cerebral innervation varies among species.

Tyramine-induced contractions in the rabbit ear and basilar arteries

This study examined in vitro tyramine (TY)-induced contractions of the isolated ring segments of the rabbit basilar and ear arteries in relation to their sympathetic innervations. The TY dose--response relationship in the basilar artery was not affected by cocaine, chronic sympathectomy, or reserpine pretreatment. However, these treatments shifted the TY dose--response relationship in the ear arteries significantly to the right. These results indicate that the TY-induced contraction in the basilar artery is due solely to its direct stimulation of the postsynaptic alpha-receptors, but in the ear artery it is due both to its indirect [release of norepinephrine (NE)] and direct actions. The failure of TY to induce contraction in the basilar artery by the indirect mechanism is probably in part due to a wide synaptic cleft distance and the reported insensitivity of alpha-receptors of this artery. These results suggest that the endogenous NE releasable from the sympathetic nerve in the basilar artery is insufficient to bring about vasoconstriction. This is turn favors our previous hypothesis that transmural-nerve-stimulation (TNS)-induced constriction of this artery is to a transmitter other than NE. It further suggests that the functional significance of the sympathetic innervations to different regions of the vessels is highly variable even when they are of the same ganglionic origin.

Genetics of serum resistance in Neisseria gonorrhoeae: the sac-1 genetic locus

A genetic locus affecting susceptibility to the bactericidal activity of normal human serum has been designated sac-1. This locus was shown to be closely linked to, but not identical with, a second locus (designated nmp-2) that affects protein 1 of the outer membrane. The sac-1 locus could be linked to known antibiotic resistance markers on the gonococcal chromosome by genetic transformation.

Io: Ground-Based Observations of Hot Spots

Observations of Io in eclipse demonstrate conclusively that Io emits substantial amounts of radiation at 4.8 and 3.8 micrometers and a measurable amount at 2.2 micrometers. Color temperatures derived from the observations fit blackbody emission at 560 K. The required source area to yield the observed 4.8-micrometer flux is approximately 5 x 10(-5) of the disk of Io and is most likely comprised of small hot spots in the vicinity of the volcanoes.

Relapse of Legionnaires' disease in a renal transplant recipient

We describe a 44-year-old man who recently received a cadaveric renal transplant and had a relapse of Legionnaires' disease after an appropriate course of therapy. The relapse occurred within two weeks after completion of a three-week course of therapy with erythromycin stearate. A transbronchial biopsy specimen was positive for Legionella pneumophila by direct immunofluorescence, although the Dieterle silver impregnation stain was negative. The patient responded to a repeated course of erythromycin for an additional 21 days, and no further sequelae or relapses have been noted. The importance of early rapid diagnostic modalities in the immunocompromised patient is emphasized, and the need to consider the possibility of relapse after effective therapy is warranted.

Neisseria meningitidis bacteremia in association with deficiency of the sixth component of complement

The serum of a 26-year-old black man with a recent episode of meningococcemia complicated by meningitis and arthritis was found to lack hemolytic complement activity. The sixth component of complement was not detected by functional or immunochemical assays whereas other components were normal by hemolytic assay. His fresh acute-phase serum lacked complement-mediated bactericidal activity against the homologous strain of Neisseria meningitidis, but the addition of fresh normal serum or purified C6 restored bactericidal activity as well as hemolytic activity. The absence of C6 activity could not be accounted for on the basis of an inhibitor. Opsonization and chemotaxis functioned normally. Histocompatibility typing of family members did not demonstrate evidence for genetic linkage of C6 deficiency with the major histocompatibility loci. This report represents the first published case of C6 deficiency associated with bacteremic Neisseria infections in which antimeningococcal bactericidal antibodies have been definitively demonstrated against the homologous strain in the acute phase of the illness.

Neisseria meningitidis and Neisseria gonorrhoeae bacteremia associated with C6, C7, or C8 deficiency

We summarize data from 24 previously described or newly diagnosed cases of homozygous deficiency of the sixth, seventh, or eighth components of complement. Thirteen of 24 patients had at least one episode, and usually two or more episodes of Neisseria meningitidis or Neisseria gonorrhoeae bacteremia, or both. Deficiency of C6, C7, or C8 is a meaningful risk factor for repeated neisserial bacteremia; conversely, hemolytic complement studies are indicated in patients who develop recurrent neisserial infections. When a person with C6, C7, or C8 deficiency is identified, family members should also be studied.

Structure of acid protease from Endothia parasitica in cross-linked form at 2.45-A resolution

The structure of acid protease from Endothia parasitica in strongly cross-linked form is compared with that of the untreated protein at 2.45-a resolution. The only observed conformation change introduced by the cross-linking reaction is at the N terminal. Otherwise the two main chain structures are essentially identical. Approximately 2 molecules of the inhibitor, 1,2-epoxy-3-(p-nitrophenoxy)propane, are found to be incorporated into each protein molecule. They are covalently bound to the two aspartic residues at the active center.

Mucocutaneous lymph node syndrome in a young adult

Mucocutaneous lymph node syndrome (MLNS) is an acute febrile illness of unknown cause first described in Japan but more recently reported in the United States. The mean age in confirmed cases was 3.8 years (range, 3 months to 13 years), and the mortality is 1% to 2% when associated with coronary artery thrombosis and aneurysm. We describe the first case of MLNS in a young adult, with the additional clinical finding of associated arthritis.

Familial deficiency of the seventh component of complement associated with recurrent bacteremic infections due to Neisseria

The serum of a 29-year old woman with a recent episode of disseminated gonococcal infection and a history of meningococcal meningitis and arthritis as a child was found to lack serum hemolytic complement activity. The seventh component of complement (C7) was not detected by functional or immunochemical assays, whereas other components were normal by hemolytic and immunochemical assessment. Her fresh serum lacked complement-mediated bactericidal activity against Neisseria gonorrhoeae, but the addition of fresh normal serum or purified C7 restored bactericidal activity as well as hemolytic activity. The absence of functional C7 activity could not be accounted for on the basis of an inhibitor. Opsonization and generation of chemotactic activity functioned normally. Complete absence of C7 was also found in one sibling who had the clinical syndrome of meningococcal meningitis and arthritis as a child and in this sibling's clinically well eight-year-old son. HLA histocompatibility typing of the family members did not demonstrate evidence for genetic linkage of C7 deficiency with the major histocompatibility loci. This report represents the first cases of C7 deficiency associated with infectious complications and suggests that bactericidal activity may be important in host defense against bacteremic neisseria infections.

Neurogenic vasodilation of cat cerebral arteries

Transmural nerve stimulation (TNS) with 0.3-msec pulses between 1 and 25 Hz dilated cat cerebral artery segments in the presence of active muscle tone. Maximum vasodilatation occurred at 8 Hz. The dilator response to exogenous acetylcholine, but not to TNS, was abolished by atropine. Neither physostigmine nor hemicholinium affected the dilator response to TNS, which persisted after administration of guanethidine, phenoxybenzamine, propranolol, reserpine, and chronic sympathectomy. However, it was abolished by tetrodotoxin and cold storage. When examined histochemically, cat and rabbit cerebral arteries exhibited a rich plexiform distribution of acetylcholinesterase which was not affected appreciably by sympathetic denervation. These results suggest that vasodilation is not mediated through modification of sympathetic activity. They also indicate the existence of a nonadrenergic, possibly noncholinergic, vasodilator innervation in cat cerebral arteries. Preliminary studies suggest that the transmitter is not histamine, ATP, prostaglandins, gamma-aminobutyric acid, dopamine, or serotonin. The cat cerebral artery segments contrast with the isolated rabbit cerebral arteries which predominantly constrict in response to TNS and show a small dilator response.

Penicillin sensitivity and serum resistance are independent attributes of strains of Neisseria gonorrhoeae causing disseminated gonococcal infection

We have determined that isolates of Neisseria gonorrhoeae from patients with disseminated gonococcal infection (DGI) are different from randomly collected isolates from patients with uncomplicated (local) disease. Our comparison was based on the six phenotypic properties of: sensitivity to penicillin (PenS), erythromycin, and streptomycin; resistance to the bactericidal effects of pooled human sera; requirements for arginine, hypoxanthine, and uracil (AHU-); and sensitivity to toxic agar. Although the marked association among these traits made analysis difficult, several factors independently related to virulence were defined. The DGI isolates were significnatly more PenS and resistant to serum, even when the other variables were held constant. An apparent correlation between AHU- auxotype and virulence was shown to be due to the PenS property of most AHU- isolates. Thus, certain mutations to antibiotic resistance as well as susceptibility to sera, may result in loss of virulence in the gonococcus, perhaps through alteration of cell envelope structure.

Effects of denervation and reserpine on nexuses in the rat vas deferens

Permanganate-fixed vasa deferentia from rats were examined for the presence of nexal-like contacts by electron microscopy. There was a significantly greater incidence of nexuses (2X) in chronically denervated tissues (5-7 days) but not in tissues from reserpine-pretreated animals (1.0 mg/kg/day for 5-7 days). The results suggest that an increase in nexal regions may not be a general feature of postjunctional supersensitivity but rather may contribute to other denervation-induced changes in contractile response.

Neurogenic sympathetic vasoconstriction of the rabbit basilar artery

When examined by fluorescence microscopy the rabbit basilar artery contains a rich adrenergic-like plexus at the adventitiomedial junction. The fluorescence disappears upon chronic reserpinization and bilateral superior cervical ganglionectomy. Transmural stimulation of intramural nerves a results in a response which is predominantly constrictor but also contains a small, inconstant dilator component. The constrictor response is abolished by chronic reserpinization, bilateral superior cervical ganglionectomy, and cold storage of the preparation. The constriction is prevented by the adrenergic neuron blocking agents guanethidine and bretylium but not by such alpha-adrenergic receptor blocking agents as phenoxybenzamine (PBZ), phentolamine, and tolazoline. Our results show that doses of the three latter agents sufficient to abolish contractions to norepinephrine (NE) in concentrations of up to 10(-2) M only potentiate and prolong the contractile response to nerve stimulation. The beta-adrenergic receptor blocking agent, propranolol, and inhibitors of NE neuronal uptake, such as desipramine (desmethylimipramine, DMI) and cocaine, do not influence the size of the neurogenic response. These results suggest that the vasoconstrictor component of the rabbit basilar artery response to transmural nerve stimulation (TNS) is mediated via sympathetic adrenergic-like neurons, but at the same time also raise the question whether the transmission process is typical of classic adrenergic neuroeffector mechanisms.

Diphenylhydantoin-induced hepatic necrosis. A case study

A patient with post-traumatic seizure disorder developed lymphadenopathy, exfoliative dermatitis, and hepatic failure while on diphenylhydantoin therapy and died in hepatic coma. Autopsy disclosed massive hepatic necrosis. The clinical and pathological pictures are similar to the six previously reported cases of diphenylhydantoin-induced hepatic necrosis, with the exception of the time of onset of hepatic failure, which is explained. The cause of such hepatotoxicity is unknown, although hypersensitivity is postulated. It appears that studies of liver function in patients receiving diphenylhydantion are indicated to assess the true indicence of hepatocellular injury.