Does lithotripsy cause hearing loss?

OBJECTIVE

To determine whether lithotripsy with the Dornier MPL9000 has any significant effect on the hearing of either patients or operators, as determined by pure tone audiometry.

PATIENTS AND METHODS

Twenty patients had audiometry prior to a single exposure to lithotripsy and one hour after treatment. Staff were monitored on a 3 monthly basis.

RESULTS

No evidence was found to suggest that single or repeated exposure to the noise emitted by this Dornier lithotripter was associated with any hearing loss.

CONCLUSIONS

These results suggest that the risk to the hearing of patients exposed to lithotripter noise is negligible. Cochlear damage resulting from excessive noise depends on both the intensity of the sound and the duration of exposure. The acoustic properties of the building housing the machine may also be important and can significantly influence the intensity of the sound at the ear. At marginal levels it may be years before the deficit reaches a level that can be detected by subjective audiometry. In addition, susceptibility to noise induced hearing loss is difficult to predict. Although these results suggest that there is minimal risk to the hearing of staff members exposed to lithotripter noise, the authors recommend that staff exposed to repeated lithotripter noise over long periods undergo regular audiometric assessment (including a preemployment baseline assessment) to identify evidence of noise induced auditory trauma, and that protective equipment be worn by staff members to reduce the possibility of long-term damage.

Pharmacokinetics and pharmacodynamics in copper deficiency. I. Antiinflammatory activity of aspirin

The effect of nutritional copper (Cu) deficiency on the antiinflammatory activity and pharmacokinetics of aspirin (ASA) was investigated in rats. Male, weanling Sprague-Dawley rats were fed either a Cu-deficient (CuD) or Cu-sufficient (CuS) diet for 49-50 d. The antiinflammatory activity of ASA was studied using the carrageenan-induced paw edema (CPE) test. ANOVA analyses of edema volumes at 2, 3, 4, 5, and 21 h postcarrageenan indicated significant differences between groups. The percent inhibition of edema due to ASA treatment in CuS was lower than that in CuD rats at 5 h, AUC5h, and AUC21h. ASA was found to be significantly more effective in inhibiting the CPE in CuD rats when compared to the CuS rats. Thus, we hypothesized that the increase in ASA's antiinflammatory activity in CuD rats was a result of a decrement in its elimination during nutritional Cu deficiency. The elimination of ASA in CuD and CuS rats was studied using an iv dose of 200 mg/kg. Concentrations of ASA and salicylic acid (SA) were determined in blood; whereas the concentrations of SA, salicylic phenol-glucuronide (SPG), and salicyluric acid (SUA) were determined in urine by HPLC. The results of the pharmacokinetic analyses from blood and urinary data indicated no significant differences in the disposition of ASA between CuD and CuS rats. For instance, the total body clearance for ASA (mean +/- SD, mL/min/kg) was 37.9 +/- 9.4 and 38.5 +/- 13.9 (p > 0.05); and the volume of distribution (Vd) for ASA (mean +/- SD, mL/kg) was 385.5 +/- 110.3 and 397.1.1 +/- 137.9 (p > 0.05) for CuD and CuS groups, respectively. Thus, contrary to our hypothesis, the enhanced antiinflammatory activity of ASA in CuD rats does not appear to be mediated via a decrement in the elimination of the drug. In addition, plasma ASA-esterase activity was found to be independent of Cu nutritional status.

Magnetic resonance imaging of urinary calculi

Accurate prediction of the response of an individual patient to lithotripsy remains impossible. Certain factors such as the chemical composition, size, and position of the calculus are known to be important in determining the success rate. This paper reports the use of magnetic resonance imaging (MRI) to evaluate 141 urinary calculi in vitro. A wide range of signals for each chemical type of calculus was found on each of the three imaging sequences used (T1-weighted, T2-weighted, and proton density). None of the chemical groups examined showed a typical MRI profile allowing it to be distinguished from the other groups. Analysis of variance showed a statistical difference between signals for apatite and struvite on the T1-weighted sequence, and between struvite and uric acid on the proton density sequence (both, P < 0.05). These results show for the first time that MRI is capable of distinguishing between different chemical types of stones. This is particularly important for the comparison of struvite and apatite which appear to be similar in conventional investigations but have quite different hardness values. Further work is in progress correlating the results of this study with stone microhardness and extracorporeal shockwave lithotripsy fragility tests to determine whether MRI accurately predicts the success of lithotripsy.

Epstein-Barr virus-coded BHRF1 protein, a viral homologue of Bcl-2, protects human B cells from programmed cell death

Epstein-Barr virus, a human herpesvirus that persists within the B-lymphoid system, can enhance the survival potential of latently infected B cells in vitro through up-regulation of the cellular survival protein Bcl-2. The possibility that an analogous effect is operative in lytically infected cells was suggested by the observation of distant sequence homology between an Epstein-Barr virus-coded early lytic cycle protein, BHRF1, and Bcl-2. Here we show by gene transfer that BHRF1 resembles Bcl-2 both in its subcellular localization and in its capacity to enhance B-cell survival. Thus confocal microscopic analysis of cells acutely cotransfected with BHRF1 and Bcl-2 expression vectors revealed substantial colocalization of the two proteins in the cytoplasm. In subsequent experiments, stable BHRF1 gene transfectants of Burkitt lymphoma cells paralleled Bcl-2 transfectants in their enhanced survival under conditions that induce cell death by apoptosis. Despite their limited sequence conservation, therefore, the two proteins appear to be functionally homologous. We suggest that BHRF1 provides an alternative, Bcl-2-independent, means of enhancing B-cell survival that may operate during the virus lytic cycle.

Breast disease and the general surgeon. II. Effect of audit on the referral of patients with breast problems

OBJECTIVES

To determine the number of patients with breast problems referred to general surgical clinics in a district general hospital and to assess the effect of changes implemented following the previous study on waiting time, investigations performed, and management of the patients.

DESIGN

Two prospective outpatient audits with patient details recorded on questionnaires by the medical staff.

SETTING

The general surgical outpatient clinics of a single general surgical firm at Newbury District Hospital, Berkshire.

PATIENTS

Those patients attending the above clinics during two 3-month periods, 1 October to 31 December 1989 (Study 1), and 16 April to 19 July 1990 (Study 2).

RESULTS

Of new referrals, 25% were for a breast problem. The waiting time fell from a median of 22 days in Study 1 to 10 days in Study 2. There was no significant difference between the studies for the proportion of each type of investigation performed. Between 80% and 85% of new patients did not need admission for an operation; however, of those operations performed, 65% were for carcinoma. The number of patients diagnosed as having carcinoma was the same in the two studies.

CONCLUSIONS

That 25% of new, and up to 40% of follow-up patients seen in a general surgical clinic have breast problems. Many patients do not regard their symptoms as worrying and will not attend early clinic appointments even if these are offered. Writing to patients and general practitioners with the results of investigations ensures quicker receipt of the diagnosis and treatment plan, and reduces follow-up attendance. Only 15-20% of new patients need admission for an operation, and carcinoma is found in only 13-17%. Open access to the clinics does not result in general practitioners referring patients unnecessarily with breast problems.

Breast disease and the general surgeon. I. Referral of patients with breast problems

OBJECTIVES

To determine the proportion of all new and follow-up patients referred to general surgical outpatient clinics with breast problems. To ascertain how long these patients wait for an appointment and how many require investigation or admission for operation. To review our management of patients with breast problems in the clinic and to determine the ratio of benign breast disease to malignancy.

DESIGN

A 3-month prospective outpatient survey with patient details recorded on questionnaires completed by the medical staff.

SETTING

The general surgical outpatient clinics of this firm at Battle Hospital, Reading, and Newbury District Hospital, Berkshire.

PATIENTS

Those patients attending the above clinics during the 3-month period 1 October to 31 December 1989.

RESULTS

In all, 693 new patients and 554 follow-up patients were seen. Of the new patients, 119, and of the follow-up patients 140 were seen for a breast complaint. At Battle Hospital 16% of all new patients presented with a breast problem, while at Newbury Hospital the figure was 24%. Of the follow-up patients at Battle Hospital, 23% were seen for a breast problem, and 41% at Newbury. The overall median waiting time for a new outpatient appointment was 21 days. No investigations were needed in 22% of the patients. The remaining 93 patients had investigations and a total of 70 mammograms and 53 fine needle aspirations for cytology were performed. The mean cost of investigations per patient investigated was estimated at 27 pounds. Of new patients, 58% were discharged from the clinic after a single consultation, and investigations as necessary. In 79% of the patients admitted for an operation, the decision to admit was made on the basis of the initial history and examination alone. Of new patients, 84% did not need admission and were managed in the clinic. In all, 14 breast carcinomas were diagnosed--12% of new patients with breast problems.

CONCLUSIONS

The figures suggest that 24% of new patients and 41% of follow-up patients attending a general surgical clinic are seen for a breast problem. The waiting time for new appointments is unacceptably long. Most new patients do not require admission for an operation. Only 12% of new patients referred with a breast problem were found to have a carcinoma.

Use of calcium alginate to pack abscess cavities: a controlled clinical trial

Many conventional dressings are painful when removed, and may be detrimental to healing. In a pilot study ten consecutive abscesses, requiring incision and drainage, were packed with a calcium alginate dressing: this was well tolerated, its removal causing minimal pain. No adverse effects were attributable to its use. A controlled trial was therefore carried out to compare calcium alginate with the more traditional saline-soaked gauze for packing abscess cavities, following incision and drainage. Patients were randomized to receive either calcium alginate (16 patients) or gauze dressing (18 patients). At the first dressing change the patient marked on a linear analogue scale the pain experienced; the nurse noted similarly the ease of removal of the dressing. Calcium alginate was significantly less painful to remove after operation (P less than 0.01), and also easier to remove (P less than 0.01) than gauze dressings. If abscess cavities are packed after incision and drainage, calcium alginate appears to be an improvement on conventional dressings.

Memory and attention in patients with senile dementia of the Alzheimer type and in normal elderly subjects

Previous studies have shown that cholinergic blockade in normal subjects induces impairment of vigilance as well as memory deficits. In the present investigation we have examined the validity of this pharmacological model of dementia by administering a battery of cognitive tasks to patients with mild and moderate senile dementia of the Alzheimer type and to age-matched controls. In contrast to volunteers receiving scopolamine all the mildly demented patients, and half of those moderately affected, performed normally on tests of vigilance whilst exhibiting the expected memory deficits. These data suggest that the mechanism of memory loss in Alzheimer's disease may differ from that found in scopolamine-induced amnesia.

HIV-1 binding to CD4 T cells does not induce a Ca2+ influx or lead to activation of protein kinases

The penetration of CD4+ cells by human immunodeficiency virus (HIV) involves a high affinity interaction between the viral attachment protein, gp120, and the cellular receptor, CD4. The mechanism by which the virus penetrates the host cell subsequent to viral binding is unknown. We have investigated the possibility that HIV penetration induces changes in the metabolic state of the infected cell similar to those seen with the perturbation of CD4 cells by monoclonal antibodies (MAb) directed against the CD4 molecule, or with specific antigen-mediated activation. The activation of cellular protein kinases was examined. The basal level of activity was not altered in the presence of HIV. Kinase activity was markedly increased in cells stimulated with phytohemagglutinin (PHA), and was qualitatively and quantitatively changed by a brief exposure to the phorbol ester TPA (12-o-tetradecanoyl phorbol-13-acetate). The phosphorylation state of the CD4 molecule was examined by radioimmunoprecipitation and found to be unaltered by the binding of HIV under conditions in which TPA induced rapid CD4 phosphorylation. The activity of the CD4-associated protein tyrosine kinase p56lck was measured by in vitro assays of 32PO4 incorporation in CD4 immunoprecipitates from HIV-incubated cells. TPA incubation resulted in a rapid loss of CD4-associated p56lck activity, presumably due to dissociation of the enzyme from CD4. Concanavalin A stimulation resulted in a similar change but with a slower time course. However, no change in CD4-associated activity was detected in HIV-incubated cells. We found that Ca2+ influx was not induced by the binding of HIV to CD4+ cells.(ABSTRACT TRUNCATED AT 250 WORDS)

A family-centered critical care unit

Although care of the family has long been a focus of nursing, there has been an increased emphasis in recent years to provide opportunities for families to be an integral part of the hospitalization experience. This has been difficult for many nurses who perceive themselves as competent to care for a patient in "medical crisis" but feel unqualified to provide family care. This article will address issues related to implementing a family-centered philosophy of care in a critical care unit. Implementation strategies that will be discussed include: formulating a staff-led family support group and family committee, instituting a family visitation contract within open visitation parameters, and developing clinicians with expertise in family care. Tools such as a performance plan for a Clinical Nurse II specializing in family care and the family visitation contract will be shared.

Families: a link or a liability?

Hospitalization in a critical care setting has multiple effects on patients and their families. For patients, it can be a frightening and dehumanizing experience, while families are confronted with stressors that can disrupt normal family functioning. The nurse is the pivotal figure in the health care system who can positively affect family coping through the support offered. With family needs met, they are then strengthened and able to support their family member. This article examines the roles and relationships of families, social support systems, and nurses. Through the framework of social support, nurses provide emotional, instrumental, spiritual, and appraisal assistances to families. This can potentially positively affect the family's adaptation to a stressful situation, and thus the family's ability to provide support to the patient. A case study analysis is described to illustrate the interactions and interventions through a model of family support.

Application of different chromosomal DNA restriction digest fingerprints to specific and subspecific identification of Campylobacter isolates

Eleven strains comprising representatives of different subspecies, biotypes, and serotypes of Campylobacter jejuni and reference strains of C. coli, C. fetus subsp. fetus, C. hyointestinalis, and C. sputorum subsp. sputorum were studied to assess the utility of different DNA profiles for measuring fine differences between allied bacteria. Strains were compared by analyses of HaeIII and XhoI digest patterns of chromosomal DNA and Southern blot hybridization patterns of XhoI digests obtained with an Escherichia coli 16S + 23S rRNA gene probe. Visual comparisons and numerical analyses of the HaeIII and XhoI digest patterns both revealed clear differences between the five Campylobacter species and between representatives of C. jejuni subspecies and biotypes. Only strains with the same Penner serotype gave identical total digest polymorphisms. The advantages of XhoI total digests and Southern blot hybridization patterns were that they were less complex than the HaeIII patterns and easier to compare visually. However, numerical analysis of XhoI data resulted in reduced discrimination. We conclude that DNA fingerprinting using either HaeIII or XhoI fragment polymorphisms has considerable potential as a generally applicable method for identification of Campylobacter isolates, especially at the infrasubspecific level.

Detection of genomic variation in Providencia stuartii clinical isolates by analysis of DNA restriction fragment length polymorphisms containing rRNA cistrons

Chromosomal DNA from 26 strains of Providencia stuartii isolated mainly in hospitals in the United Kingdom and reference strains of P. stuartii, P. rustigianii, and Proteus vulgaris were digested with the restriction endonucleases EcoRI and HindIII. After electrophoresis in agarose gels, the fragments were subjected to Southern blot hybridization analysis with a biotin-labeled cDNA probe transcribed from a mixture of 16S and 23S rRNA from P. stuartii NCTC 11800T. The pattern of bands (the rDNA fingerprint), which depended on restriction fragment length polymorphisms containing rRNA genes, was used as a measure of minor genomic variation within and between species. The P. stuartii clinical isolates had similar total digest patterns, but the rDNA fingerprints revealed some heterogeneity between strains, with EcoRI digests providing better strain discrimination than HindIII. Such rDNA fingerprints comprised between five and seven bands with sizes in the range of 5 to 28 kilobases. The 11 different EcoRI patterns were compared by numerical analysis, and several groups or subgroups of strains were identified. Over half (15 of 26) of the urease-negative isolates (subgroups Aa and Ab) had patterns that differed only by the presence or absence of a 25-kilobase band. Urease-negative strains from other clinical material were more heterogeneous in their patterns. No correlation was apparent between strain pattern group and urease production or geographic location of isolate. The P. stuartii rDNA fingerprints were quite distinct from those of allied Providencia and Proteus species and provided a more sensitive measure of minor genomic differences than total DNA digests did.

Toronto Alexithymia Scale: relationships with measures of patient self-disclosure and private self-consciousness

The construct validity of the Toronto Alexithymia Scale (TAS) was tested by correlations with the Patient Self-Disclosure instrument and the Private Self-Consciousness scale in a study of 333 students at a large midwestern university. The TAS was found to be internally consistent and to yield a replicable factor structure. Scores on the TAS correlated negatively with both overall ratings of the importance of such disclosure and scores on the PSC, and positively with perceived difficulty of patient self-disclosure. Results support construct validity of the TAS and suggest a more generally restrictive communicative style among alexithymic individuals than previously thought.

Hypoxic induction of Ca2+-dependent action potentials in small pulmonary arteries of the cat

Small pulmonary arteries (less than 300 micron) from cats were mounted in myographs to record mechanical and electrical responses to hypoxia. When these preparations were exposed to a PO2 of 30-50 Torr after equilibration at 300 Torr they consistently developed active force, which increased or decreased in amplitude as [Ca2+] was raised or lowered, respectively, and was blocked on addition of verapamil. Intracellular electrical recording with glass microelectrodes demonstrated membrane depolarization and action potential generation when PO2 was lowered. Steady-state voltage vs. applied current curves obtained before and during hypoxia showed a significant reduction in input resistance. The relationship between membrane potential and extracellular K+ was not different during hypoxia compared with control, suggesting that there were not marked changes in K+ permeability under this condition. In the presence of verapamil to block Ca2+ inward current the hypoxia-induced action potentials were abolished concomitant with partial membrane repolarization. The results of these studies suggest that in certain isolated pulmonary arteries hypoxia induces contraction by a mechanism involving an increased Ca2+ conductance. These data suggest that the sensor involved in hypoxic pulmonary vasoconstriction may lie within the vessel wall and somehow mediates changes in smooth muscle ionic conductances.

A membrane electrical mechanism for hypoxic vasoconstriction of small pulmonary arteries from cat

Using specially fabricated muscle myographs, we examined electrical and mechanical responses to reduction of PO2 in small (less than 300 micron) pulmonary arteries excised from cat lungs. Upon lowering PO2 from 400 to 50 mm Hg, these preparations consistently developed contractile responses concomitant with membrane depolarization and action potential generation. The largest changes in electromechanical responses to reduction of PO2 occurred between 150 and 50 mm Hg. These data strongly suggest that hypoxic activation of small pulmonary arteries is mediated by direct effects of reduced PO2 on muscle cell membrane ionic conductance systems.

Hypertension, perceived clinician empathy, and patient self-disclosure

The purpose of this study was to compare groups of outpatient hypertensive and diabetic patients to a control group (no known chronic illnesses) on their perceptions of clinician empathy and the importance and difficulty of disclosing information about themselves to health care providers. It was hypothesized that hypertensives would differ from the other groups in perceiving less clinician empathy and in attributing less importance, but greater difficulty, to self-disclosing. The sample was 54 hypertensives, 47 diabetics, and 115 nonchronically ill patients. Each subject completed the Empathy scale of the Barrett-Lennard Relationship Inventory and a patient self-disclosure questionnaire. The empathy hypothesis was supported but the self-disclosure hypotheses were not. Hypertensive patients differed from other patients in perceiving the least clinician empathy and in attributing the greatest importance to discussing their responses to health care.

Muscarinic cholinergic receptors in rabbit retina

Binding sites with high affinity and specificity for [3H]-quinuclidinyl benzilate are present in rabbit retinal homogenates. Only one set of binding sites was detected with an apparent dissociation constant of 2.13 X 10(-10) M and a density of 59.2 fmol mg-1 of protein. The pharmacological characteristics of specific binding were similar to those in the goldfish, chicken and cow.

A patient self-disclosure instrument

Four studies in which a patient self-disclosure questionnaire was developed and tested are reported. The instrument was designed to include only content judged by both patients and clinicians as important. Three areas of patient difficulty in disclosing to a health care provider were measured: personal problems and feelings, responses to health care, and life style. Patient difficulty in disclosure was assessed by 21 7-point rating scales, 7 for each disclosure area; ratings were summed to obtain scores. A correlation matrix of the ratings of 216 patients was subjected to a three-factor principal components analysis with varimax rotation; the solution accounted for 59% of the total variance. High internal consistency and test re-test reliability for the total scale and subscales were obtained; Cronbach's alpha .82-.83, n = 214; r = .81-.87, n = 66. In separate tests of construct validity patient self-disclosure was shown to be influenced by locus of control and perception of clinician empathy, and to covary with heart rate changes.

Taurine uptake processes in the isolated rabbit retina and the effects of light

As part of a study on the mechanisms involved in regulating photoreceptor taurine levels, we have examined the characteristics of [3H]-taurine uptake by the isolated rabbit retina. The effects of light on taurine accumulation have also been studied. Rabbit retinas quickly accumulated [3H]-taurine and tissue: medium ratios of 50:1 were attained after 60 min incubation at 37 degrees C. Under these conditions no metabolites of [3H]-taurine were detected in the tissue. The efflux of [3H]-taurine from the retina was extremely slow, less than 5% of the accumulated radioactivity being released in a 30 min incubation in fresh medium. Thus, in subsequent experiments the accumulation of radioactivity was taken as a measure of [3H]-taurine uptake. Non-linear regression analysis of kinetic data revealed that taurine was accumulated by separate high- and low-affinity transport processes, the kinetic parameters being Kmh = 93 +/- 12 microM; Vmh = 72 +/- 7; KmL = 8.8 +/- 5 mM; VML = 274 +/- 79 nmol min-1 g-1 wet weight respectively. The properties of the high- and low-affinity taurine uptake processes were very similar. Both were temperature sensitive, particularly between 25 and 37 degrees C and sodium- and chloride-dependent, and were inhibited by metabolic inhibitors. The substrate specificities of the high- and low-affinity uptake processes were also similar, both processes being inhibited by beta-alanine, guanidinoethylsulphonate (GES) and GABA, but not by alpha-alanine or glycine. Hypotaurine selectively inhibited the high-affinity uptake process for [3H]-taurine. Exposure of retinas to continuous light did not affect either the high- or the low-affinity uptake of [3H]-taurine compared with dark-adapted controls. However, flickering light (0.5-30 Hz, 25% duty cycle) reduced the high-affinity accumulation of [3H]-taurine by as much as 50%. The reduction in [3H]-taurine may be due to a localized decrease in uptake (or possibly an increased release) by the photoreceptors because the same reduction was found when synaptic transmission in the retina was blocked by exposure to medium containing high Mg/low Ca. High Mg/low Ca did not itself affect taurine accumulation.

Herpes simplex virus infection causes the accumulation of a heat-shock protein

A monoclonal antibody, produced from mice immunized with a herpes simplex virus (HSV)-infected cell extract, reacts with a molecule which is present in uninfected cells and which accumulates in large amounts during HSV 2 infection. In uninfected cells this molecule is growth regulated, in that exponentially growing cells have intense nuclear immunofluorescence, whereas confluent quiescent cells have little. It has a mol. wt. of 57 000 (p57) in exponential cells, and one of 61 000 (p61) in quiescent cells. In HSV 2-infected cells, p57 accumulates and nuclear and cytoplasmic immunofluorescence increases. In uninfected cells, p57 also accumulates during heat-shock treatment, and this is associated with a new immunofluorescence throughout the cytoplasm. We suggest that HSV 2 infection induces a cellular stress response which is involved in the shut-off of host cell polypeptide synthesis.

Evidence for a cholinergic inhibitory feed-back mechanism in the rabbit retina

The effects of muscarine, atropine and nicotinic antagonists on the light-evoked release of radioactivity from rabbit retinas previously exposed to [3H]choline (Ch) was studied. On the basis of previous experiments, this light-evoked release of total radioactivity was taken as a measure of the light-evoked release of [3H]acetylcholine (ACh) from the cholinergic amacrine cells. Atropine (1 microM) in the presence, but not the absence, of eserine more than doubled the light-evoked release of [3H]ACh. Eserine (30 microM) itself had no significant effect on either the spontaneous resting release or the light-evoked release of [3H]ACh. Muscarine (10 microM) in the presence or absence of eserine reduced the light-evoked release of [3H]ACh from the retina by 50%. This effect of muscarine was blocked by atropine used in the absence of eserine. The nicotinic antagonists pempidine, hexamethonium and gallamine had no significant effect on retinal [3H]ACh release. Strychnine (20 microM), which alone had no effect on retinal [3H]ACh release, abolished the effects of both muscarine and atropine on the light-evoked release of [3H]ACh. Bicuculline (5 microM) did not affect the actions of muscarine or atropine on the light-evoked release of [3H]ACh. Previous experiments had shown that glycine and gamma-aminobutyric acid (GABA) reduce the light-evoked release of [3H]ACh from the retina and that these inhibitory effects are selectively blocked by strychnine (20 microM) and bicuculline (5 microM) respectively. These results suggest the presence in the retina of a cholinergic inhibitory feed-back mechanism which involves a neuronal loop, rather than presynaptic or post-synaptic inhibitory muscarinic receptors on the cholinergic amacrine cells themselves. Our experiments do not provide evidence on the nature of the proposed inhibitory loop, except that it apparently includes a glycinergic or taurinergic (amacrine) cell.

Thygeson's superficial punctate keratitis

Thygeson's superficial keratitis is a chronic disease of the cornea characterized by focal epithelial lesions. We studied 45 cases of Thygeson's superficial punctate keratitis. Twenty-eight were male and 17 were female patients. The disease had been active in our patients from one month to 24 years. The clinical findings, course, outcome, and response to therapy were studied. Viral cultures and microscopic studies were performed on the corneal epithelial scrapings from ten cases. The average course of the disease was prolonged in patients who received topical steroid therapy. Subepithelial opacities were seen more frequently in patients who had received treatment with idoxuridine (IDU).

Stimulation of peroxidase by chlamydial infection: cytochemistry of guinea pig conjunctival epithelium

Guinea pig inclusion conjunctivitis, a naturally occurring chlamydial disease of guinea pigs, resolves spontaneously after 3 to 4 weeks. The factors responsible for curbing the infection have not yet been specifically defined. Since Iwata (Invest. Ophthalmol. 15:297-301, 1976) reported cytochemical activity for peroxidase in the conjunctival epithelium of the normal rat, we undertook these studies to determine whether a similar activity exists in the guinea pig, and if so, whether it functions in the elimination of this Chlamydia psittaci infection. Tarsal conjunctivas of 14 normal guinea pigs, 34 infected ones, and 7 control guinea pigs (inoculated with yolk sac only) were excised and tested for peroxidase by the Graham and Karnovsky method (J. Histochem. Cytochem. 14:291-302, 1966). We found that peroxidase activity, virtually absent in normal animals, was intensely stimulated by the infection. This enzymatic activity appeared 2 days after inoculation of the conjunctiva with chlamydia and persisted for 6 to 7 weeks. The enzyme was localized in the rough endoplasmic reticulum and perinuclear cisternae of all layers of the conjunctival epithelium from the external surface to the basal lamina, including cells with no apparent inclusions as well as those heavily parasitized. Reaction in the Golgi complex was variable. No reaction, however, was ever evident in the chlamydial vacuoles or lysosomes, and the organisms continued to grow and multiply during peak enzymatic activity. We therefore concluded that the stimulated enzyme is apparently not directly responsible for the waning of the infection, but instead reflects an alteration of host metabolism that occurs as a consequence of the infection.

Nonantigenicity of lincomycin

We demonstrated that herpes simplex virus types 1 and 2, including a type 2 strain which transforms hamster cells in vitro, and Herpesvirus saimiri are inactivated by exposure to thiosemicarbazones. Because thiosemicarbazones are thought to interact with heavy metals in this inactivation process (9), we tested and found some of these herpesviruses to be susceptible to exposure to certain heavy metals. A virion polymerase was sought because the ribonucleic acid (RNA)-dependent deoxyribonucleic acid (DNA) polymerase of Rous sarcoma virus and the DNA-dependent RNA polymerase of vaccinia virus are inhibited. However, neither DNA nor RNA polymerase activity could be demonstrated in herpes simplex virions. The ability of thiosemicarbazone to ameliorate the course of herpes simplex virus infection in rabbit eyes was observed, but was considered insufficient to be of clinical importance.