Surgical trauma to the lateral semicircular canal with preservation of hearing

Surgical trauma to the lateral semicircular canal (LSC) is a rare complication which does not always result in cochlear damage. The authors present six such cases, discuss the histopathological findings of one case, and review 12 previous reports. Transient cochlear depression with normalization of function within 6 weeks of trauma occurred in most instances. Vestibular symptoms were pronounced and, although compensation was not delayed, positional dizziness and instability usually persisted for several months and occasionally for a year or more. Histopathological findings (two specimens) were significant for obliterative scarring of the LSC at the site of injury and for the structural integrity of the labyrinth and cochlea. The mechanism of cochlear protection in these cases remains obscure; however, clean injuries away from the ampullary end of the canal occurring in patients without preexisting inner ear disease appear to have a better prognosis. Intraoperative closure of the defect, postoperative bed rest, and antibiotics are the basic elements of management.

Synovial membrane-cartilage interactions--the role of serine proteinase inhibitors in interleukin-1 mediated degradation of articular damage

Using a peritoneal macrophage/articular cartilage co-culture system, it was shown that the serine proteinase inhibitor derived from human articular cartilage modulated the release of 35S-labelled proteoglycan into media in a concentration dependent manner. Since the cartilage inhibitor fractions used were free of metallo-proteinase and cysteine proteinase inhibitory activity, but strongly inhibited serine proteinases, it was suggested that such enzymes may be implicated in the activation of latent metallo-proteoglycanases produced by chondrocytes on exposure to IL-1.

Antecedents and outcome of very early neonatal seizures in infants born at or after term

Recent experimentally derived evidence has confirmed earlier suggestions that seizures which occur within 48 h of birth in babies born at or later than 37 completed weeks gestation are particularly likely to reflect intrapartum asphyxia. We have compared 54 cases of such seizures with 41,090 controls in a geographically defined population. Nulliparity, hydramnios, post-term pregnancy, oxytocin augmentation of labour, abnormalities of fetal heart rate and/or meconium-stained amniotic fluid, prolonged second stage of labour, emergency caesarean section, assisted vaginal delivery, low Apgar score and resuscitation at delivery and subsequent ventilatory support were all statistically significantly more common among cases than among controls. Five of the 54 babies who developed seizures died within 28 days of birth and 11 of the 49 survivors had an impairment diagnosed by 3 years of age which was usually associated with some degree of cerebral palsy. Comparison of the frequency of antecedent perinatal risk factors in the seizure babies who died, those who survived with disabilities and normal survivors failed to reveal any clear pattern.

Bridging bronchus and posterior left pulmonary artery: a unique association

A 6-month-old female with a lifelong history of respiratory distress became increasingly difficult to manage and required right upper and middle pulmonary lobectomies for worsening emphysema and mediastinal shift. The postoperative course was stormy and confusing and the patient died despite emergency tracheostomy. The autopsy disclosed an anomalous bronchus to the right lower lobe, originating from the left mainstem bronchus. In addition, the left main pulmonary artery was positioned posterior to the left mainstem bronchus. Two other cases of bridging bronchus have been reported, but the association with posterior left pulmonary artery has not been described.

Ventilatory dysfunction in palatal myoclonus

A patient with palatal myoclonus and involvement of respiratory muscles is described. Partial characterization of the mechanism of ventilatory dysfunction was achieved using noninvasive tests. Ventilatory dysfunction in this disorder can be manifested in different patterns depending on which respiratory muscles are involved predominantly.

Injury to hepatocytes induced by a peptide toxin from the cyanobacterium Microcystis aeruginosa

The freshwater, bloom forming cyanobacterium (blue-green alga) Microcystis aeruginosa produces a peptide hepatotoxin which causes death accompanied by liver necrosis. We show here that the time and dose-dependent blebbing of isolated hepatocytes is accompanied by the activation of phosphorylase a, with no changes in cyclic AMP levels, and by glutathione (acid-soluble thiols) depletion. These results suggest that the disruption of cytoskeletal structures is accompanied by disturbances in cellular calcium homeostasis and by decreased protection against oxidative damage to the cells.

The effects of recent oral contraceptive use on the outcome of pregnancy

Of 10479 singleton pregnancies in South Glamorgan between January 1974 and June 1976, 27.3% occurred in women who had used oral contraceptives in the 3 months prior to their last menstrual period (users) and 72.7% occurred in women who had not used oral contraception during the same period (non-users). Significantly more users gained weight excessively. Oral contraceptive use increased the likelihood of uncertain dates and post-maturity. The incidence of neural tube defects was higher among children born to users, although the overall perinatal outcome was not adversely affected. The sex distribution of the offspring was the same in both groups.

The role of a functionally distinct IgM anti-type III pneumococcal polysaccharide (SIII) in low-dose paralysis to SIII in mice

Prior treatment (priming) with a weakly immunogenic dose of Type III pneumococcal polysaccharide (SIII) results in the development of an antigen-specific state of unresponsiveness termed low-dose paralysis which is believed to be mediated by suppressor T cells. The present findings show that the passive administration of functionally distinct non-complement-fixing (NCF) IgM anti-SIII antibodies either in monoclonal form or from protein-A absorbed immune serum could significantly suppress the direct plaque-forming cell (PFC) response to an immunogenic dose of SIII administered concurrently. The degree of suppression was comparable with that induced by low-dose paralysis. Low-dose paralysis was consistently induced in athymic (nude) mice 4 days, but not 3 days, after priming with a low dose of SIII, and was associated with the delayed appearance of NCF-IgM anti-SIII in the serum of athymic mice. In contrast, low-dose paralysis was readily induced in normal BALB/c mice 3 days after priming when NCF-IgM anti-SIII antibodies were present. Comparable inhibiton of the direct anti-SIII PFC response was observed when Concanavalin A (Con A) or NCF-IgM anti-SIII serum was administered with SIII antigen. That Con A and NCF-IgM anti-SIII together did not produce additive suppression was attributed to the adsorption of NCF-IgM anti-SIII antibodies to Con A. Complement-dependent single radial haemolysis mediated by CF hybrid IgM/A or CF-IgM anti-SIII serum was blocked by monoclonal NCF-IgM or IgA anti-SIII antibodies and indicated that each of the antibodies was specific for the same SIII-determinant. Evidence is presented to show that low-dose paralysis in the CF-IgM response to SIII is not mediated by suppressor T cells but can be attributed to highly avid NCF-IgM anti-SIII antibodies, formed preferentially to low doses of SIII, being able to reduce the immunogenicity of SIII administered subsequently. We propose that low-dose paralysis to SIII is the result of an immunobiological function of highly avid NCF-IgM anti-SIII antibodies which not only confer resistance against capsulated pneumococci but preferentially bind soluble SIII-antigen to reduce its immunogenicity and thereby protect specific CF-IgM positive B cells from being rendered tolerant by direct contact with higher doses of SIII antigen.

Lack of relationship between serum gp70 levels and the severity of systemic lupus erythematosus in MRL/l mice

In the MRL/l mouse, gp70 apparently plays a role as an autoantigen in the development of SLE. However, while gp70 may be an important pathogenetic element, it is not essential to MRL SLE, since elimination of most of the serum gp70 and virtually all of the immune complex gp70 from MRL/l-low gp70 congenic lines had no observable effect on the course or nature of the disease. Thus, while gp70 in the MRL/l mouse appears to be a convenient autoantigenic target when present in significant levels, in its absence the host appears capable of directing its aberrant immunologic responsiveness elsewhere with undiminished pathogenicity.

Phosphatidylglycerol synthesis in pea chloroplasts: pathway and localization

Isolated intact pea chloroplasts synthesized phosphatidylglycerol from either [(14)C]acetate or [(14)C]glycerol 3-phosphate. Both time-course and pulse-chase labeling studies demonstrated a precursor-product relationship between newly synthesized phosphatidic acid and newly synthesized phosphatidylglycerol.The synthesis both of CDP-diacylglycerol from exogenous phosphatidic acid and CTP, and of phosphatidylglycerol from exogenous CDP-diacylglycerol and glycerol 3-phosphate, could be assayed in fractions obtained from disrupted chloroplasts. Moreover, the enzymes catalyzing these reactions were localized in the inner envelope membrane. Exogenous phosphatidic acid was incorporated into phosphatidylglycerol, but only following its incorporation into CDP-diacylglycerol. Finally, radio-active phosphatidic acid synthesized in the envelope membranes from [(14)C]palmitoyl-ACP and 1-oleoyl-glycerol 3-phosphate was sequentially incorporated into labeled CDP-diacylglycerol and phosphatidylglycerol upon the addition of appropriate substrates and cofactors. Thus, we have demonstrated that (a) the synthesis of phosphatidylglycerol in chloroplasts occurs by the pathway: phosphatidic acid --> CDP-diacylglycerol -->--> phosphatidylglycerol, and (b) phosphatidylglycerol synthesis is located in the inner envelope membrane.

Vestibulo-ocular reflexes in peripheral labyrinthine lesions: III. Bilateral dysfunction

Measurements were made of the lesion-induced changes in vestibulo-ocular reflexes (VOR) to rotatory stimuli in a group of patients with bilateral peripheral labyrinthine lesions. All the patients had caloric responses that were below the confidence levels used for normal responses in our laboratory. Responses to rotatory stimuli were greatly decreased or absent at low frequencies of stimulation, but present to a much greater degree at the higher frequencies. Phase measurements showed an increase in relationship to the velocity of the stimulus; there was a corresponding shortening of the time constant as obtained from impulse response measurements. A parametric study indicated that the changes in the responses can be described by a decrease in the sensitivity coefficient and in the basic time constant of a simplified pendulum model equation of vestibular function. A theoretical analysis of the data using a new model for the organization of the vestibular pathways indicated that the preservation of the high-frequency responses was the result of adaptive changes brought about in the central vestibular pathways and/or changes in the receptor-neuron transduction characteristics. Thus, despite the almost complete absence of any caloric response, the vestibular system reflexes remained adequate to maintain gaze during normal head movements.

A recommended approach to the evaluation of human rabies exposure in an acute-care hospital

It is important to minimize the costs and risks associated with unnecessary prophylaxis of health care workers. We studied the process of providing rabies postexposure prophylaxis following the 24-day hospitalization of a rabies-infected patient. Of 209 persons who cared for the patient, only 12 (6%) reported high-risk contact, and treatment was recommended for them. Unnecessary prophylaxis was limited to 35 persons (18%) who did not report high-risk contacts but who requested treatment because of their uncertainty about the degree of exposure. These persons, however, spent significantly more time with the patient compared with persons who did not request treatment. Maintaining strict isolation precautions when rabies is being considered, educating employees about the risks of transmission in this setting, carefully documenting exposures, and adhering to the guidelines for postexposure prophylaxis may help reduce excessive prophylaxis of health care workers.

Final step of phosphatidic Acid synthesis in pea chloroplasts occurs in the inner envelope membrane

The second enzyme of phosphatidic acid synthesis from glycerol-3-phosphate, 1-acylglycerophospate acyltransferase, was localized to the inner envelope membrane of pea chloroplasts. The activity of this enzyme was measured by both a coupled enzyme assay and a direct enzyme assay. Using the coupled enzyme assay, phosphatidic acid phosphatase was also localized to the inner envelope membrane, although this enzyme has very low activity in pea chloroplasts. The addition of UDP-galactose to unfractionated pea chloroplast envelope preparations did not result in significant conversion of newly synthesized diacylglycerol to monogalactosyldiacylglycerol. Thus, the envelope synthesized phosphatidic acid may not be involved in galactolipid synthesis in pea chloroplasts.