Enhancement of transmembrane proton conductivity of protonophores by membrane-permeant cations

The rate of protonophore-mediated decay of pH gradient across lipid vesicular membranes was found to be enhanced by orders of magnitude by valinomycin-K+. Experiments in the presence of gramicidin have shown that the observed rate enhancement by valinomycin-K+ is not due to collapse of the diffusion potential alone. The enhancement of the rate showed hyperbolic dependence on the concentration of valinomycin. Rate enhancement was observed in the presence of the membrane permeant cation tetraphenylphosphonium (TTP+) also. Several factors which might enhance the intrinsic H+ conductivity of protonophores were analyzed. The level of partitioning of the protonophore into the membrane and the pK of membrane-bound protonophores were measured. Valinomycin-K+ did not alter both these parameters significantly. TPP+ increased the partitioning of protonophores and decreased the pK values of membrane-bound protonophores. However, these changes were too small to explain the observed rate enhancements. We suggest that valinomycin-K+ and TPP+ enhance the H+ conductivity of protonophores by increasing the permeability of the ionized form of protonophores by forming an ion pair.

The relationship of expression of statin, the nuclear protein of nonproliferating cells, to the differentiation and cell cycle of astroglia in cultures and in situ

Cells in the quiescent, nonproliferative state express a protein, statin, in their nuclei. When the cells reenter the cell cycle, statin disappears and another protein, cyclin, appears. We have examined mouse astroglia at various stages of differentiation in cultures and astroglia in adult mouse brains for the presence of statin. In cultures initiated from the neopallium of newborn mice, the glial fibrillary acidic protein (GFAP)+ stellate astrocytes were statin-negative (statin-) but cyclin-positive (cyclin+). In the same cultures, large flat cells (senescent cells) were statin+ but cyclin-. In frozen sections of the brains of adult mice and in brain smears, GFAP+ astrocytes were statin-. Neither stellate astrocytes grown in cultures for 30 or more days nor astrocytes in adult mouse brain were labeled when pulsed with bromodeoxyuridine (BudR). When astroglia were treated with dibutyrl cyclic adenosine monophosphate (dBcAMP), large stellate cells that closely resemble reactive astrocytes in situ formed. These cells were all statin+ from 11-62 days in vitro; however, reactive astrocytes in mouse neopallium, 4-50 days after a stab wound, were statin-. In colony cultures, senescent cells became statin+, whereas stellate astrocytes and their precursor cells remained statin-. These observations indicate that normal astrocytes both in cultures and in situ retain the potential to divide and probably progress through the cell cycle at a very slow rate.

Histopathologic characteristics of dysplastic nevi. Limited association of conventional histologic criteria with melanoma risk group

Studies of dysplastic melanocytic nevi (DMN) have suggested that lesions from patients with a personal or family history of malignant melanoma are histologically more atypical than are those from control populations without such histories. To evaluate this possibility, we examined histologic sections of DMN that had been removed from patients in three groups. Group A consisted of 17 subjects with a past history of melanoma; group B comprised 79 subjects with DMN and a family history of melanoma in first-degree relatives; group C consisted of 64 subjects who were unrelated spouses of members of groups A and B. For each group, sections of DMN were initially selected on the basis of architectural atypia as defined by the National Institutes of Health Consensus Conference. All biopsy material was then further evaluated for four histologic features suggested to be discriminatory for DMN associated with increased melanoma risk; the features are degree of junctional activity, irregularity of melanocytic nests, presence of dusty melanin, and size of melanocytic nuclei. A subjective rating was given for each on a 0 to 3 scale of increasing severity. Three pathologists individually rated the specimens without knowledge of the patient group. The means of the individual observer cumulative scores of the four histologic criteria for each biopsy specimen and the average of these means from the three observers exhibited a trend to increasing values from groups C to A, but none of the differences reached statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Toxicity of nicotine derivatives and their effect on the protein pattern of 4th immature stage of red cotton stainer Dysdercus koenigii (Fabr) (Hemiptera: Pyrrochoridae)

Toxicity of Nicotine dust and Nicrotine cyanurate was observed against the 4th immature stage of Dysdercus koenigii (Fabr.) by injection method. Mortality rates were noted after 24 hours of treatments. LD50's were calculated as 7.2 microg/nymph and 9 microg/nymph for nicotine dust and nicotine cyanurate respectively. Changes in the flow of protein metabolites occur with higher and lower doses of both the compounds.

Multicomponent spectrophotometric assay of sulphacetamide and photodegradation products

A multicomponent, spectrophotometric method has been developed for the simultaneous determination of sulphacetamide, sulphanilamide and major degradation products in photolysed solutions. It is based on a three component (Sulphacetamide, sulphanilamide and azobenzene-4, 4'-disulphonamide) assay at pH 4.0 using 258, 268 and 320 nm as analytical wavelengths. The blue oxidation product of sulphanilamide is determined independently at 550 nm. The reproducibility of the method judged by the analysis of synthetic mixtures, is within +/- 5%. The method is stability indicating for the assay of sulphacetamide in degraded eye-drop preparations and could also be conveniently used for photodegradation studies.

The kinetics of timolol in the rabbit lens: implications for ocular drug delivery

This study examines the uptake and distribution of timolol in the rabbit lens following topical instillation using a heuristic approach. The implications of anisotropic drug diffusion through the lens are presented here and discussed in the context of actual in vivo data. The dynamics of timolol in the lens involve an initial, rapid uptake of the drug by the capsule and epithelium followed by slower, anisotropic diffusion through the cortex body. Kinetically, the capsule and epithelium can be treated as a separate compartment which is distinct from the cortex and which serves to provide a concentration gradient for subsequent diffusion of timolol into the dense interior structures of the lens. Model simulations support the hypothesis that the preferred route of penetration of timolol into the vitreous humor via the lens is the diffusion of drug around the capsule/epithelium and peripheral cortical layers. It is also shown that due to the high and increasing diffusional resistance toward the center of the lens, as well as the diminishing drug concentrations in the capsule and epithelium, steady-state levels in the lens may be extremely difficult to achieve in some therapeutic situations. This phenomenon could have a significant impact on the success or failure of a drug treatment involving the lens and ocular tissues.

A 48 kilodalton intermediate filament associated protein (IFAP) in reactive-like astrocytes induced by dibutyryl cyclic AMP in culture and in reactive astrocytes in situ

In this paper we demonstrate that the 48 kilodalton (kDa) intermediate filament associated protein (IFAP), previously reported to be present in normal astrocytes, is also present in reactive astrocytes in situ and in reactive-like astrocytes induced by dibutyryl cyclic AMP in vitro. This IFAP is detectable by antibodies in normal rabbit serum (F2N) and is closely associated with glial fibrillary acidic protein-containing intermediate filaments (IF). The expression of 48 kDa IFAP is related to the acquisition of stellate shape by normal and reactive-like astrocytes in vitro. It is proposed that 48 kDa IFAP may be responsible for cross-linking IF into bundles and is thereby associated with cell process formation.

Traumatic diaphragmatic hernia: review of 15 cases

From January 1985 to December 1987, 292 laparotomies were performed for injury in Riyadh Central Hospital. Of these, 15 cases were associated with diaphragmatic injuries (5.1 per cent). The diagnosis was missed in 5 cases (30 per cent) and was incidental (at laparotomy) in 3 cases (20 per cent). Therefore in about 50 per cent of the cases, the diagnosis was not made at the initial presentation. In this paper we stress the importance of maintaining a high degree of clinical suspicion in order not to miss traumatic diaphragmatic hernia in multiply injured patients.

Dementia, mental retardation, and competency to make decisions

The psychiatric literature on competency indicates that a diagnosable psychiatric condition alone does not imply incompetency to make treatment decisions. Nonetheless, it is frequently assumed that individuals who are either mentally retarded or demented are incompetent to make decisions. The authors, focusing on the clinical assessment of judgment and decision making, describe two cases. In both, the patients' judgments were intact. The authors conclude: (1) Diagnosis is not the critical factor in determining competency. (2) The process of judgment and decision making has to be assessed on a case by case basis. (3) Further research is needed to develop clinical instruments to assess judgment.

Predictive value of the electroencephalogram in acute hemispheric lesions

We studied the electroencephalogram and computed tomography in twenty cases with ischemic strokes with unilateral electroencephalographic slowing associated with abnormality of background activity on the contralateral side, compared with twenty other cases who had primarily unilateral electroencephalographic abnormality and no contralateral slowing. Electrographic parameters evaluated included field, amplitude, frequency, persistence and reactivity of focal or lateralized slowing. Computed tomographic findings studied included lesion size, density, mass effect and location. Clinical findings studied included level of consciousness and outcome. Contralateral abnormality of background rhythm correlated with impairment of consciousness and poor outcome.

Mitral annular calcification and coarctation of aorta

Although coarctation of the aorta is associated with various cardiac abnormalities, its association with mitral annular calcification (MAC) is not reported. We therefore report a 37-year-old patient with postductal coarctation of the aorta and MAC. Considered to be a degenerative process, MAC is usually seen in elderly patients. It is uncommon in patients less than 50 years old and rare before the age of 40 years. Previous studies have reported increased frequency of cardiac conduction disturbances in patients with MAC compared to age- and sex-matched controls. This is in agreement with complete right bundle-branch block noted on the electrocardiogram of our patient. Clinicopathologic correlative studies and long-term follow-up may determine how such conduction disturbances develop and progress.

Association of double NOR variant with Turner syndrome

A study was made of the possible association of double nucleolus organizers (dNORs) with Turner syndrome. Occurrence of dNORs was determined using the silver staining method of Goodpasture and Bloom [1975]. In 45 control subjects, the incidence of dNORs was 8.8%. Studies were done on 33 Turner syndrome patients. In 28 cases with 45,X or 45,X/46,XX karyotypes, the incidence of the dNOR variant was 50%. Five cases of Turner syndrome with X rings or X isochromosomes were negative for dNORs. Analysis of the data indicates an association between the dNOR variant and the occurrence of Turner syndrome. It is proposed that the presence of the dNOR variant can increase the rate of nondisjunction of the X chromosome in meiosis or in mitotic divisions during early gestation.

Use of somatosensory evoked responses in the prediction of outcome from coma

Present data on 60 comatose patients with head trauma, hypoxia and cerebrovascular disease suggested that SER may yield quantitative, useful information concerning the functional state of the cerebral cortex. To assess the prognosis of individual patients we propose to classify patients from various etiologies of coma into the following categories: I. If there is bilateral absence of cortical responses, irrespective of the etiology of coma, none of these patients recover. II. If the initial cortical responses in the first 24 hours are normal, then it is imperative that these should be repeated in the first week before any definitive prognosis can be given, (since as in one case, we noted on the fifth day there was distortion of amplitude of his response and eventually the cortical responses were unobtainable, therefore indicating a poor prognosis). III. Patients who have normal responses throughout the acute course of illness carry an excellent prognosis from coma of all etiologies, except with ischemic etiology. The prognosis remains favorable for recovery from coma, but these patients may remain with significant neurological deficits. IV. When there is a 75% drop in the amplitude of the responses, it indicates a poor prognosis for ultimate neurological recovery, and the majority of these patients will remain in a persistent vegetative state. V. In patients with intermediate reduction in amplitude, 25-50% carried a moderate prognosis, and the majority of these cases in our series were able to perform activities of daily living.

Absence status epilepticus resulting from metrizamide and omnipaque myelography

Two cases of absence status are described, one case following metrizamide myelography and the other from omnipaque myelography. Metrizamide has been well known to cause convulsive seizures even in patients without epilepsy. The exact mechanism is not known but appears to be direct neuronal toxic effects possibly due to competitive inhibition of hexokinase activity. The acute confusional state following myelography from water soluble agents is reviewed. In view of the difficulty in clinical diagnosis and the excellent response to anticonvulsant therapy, the possibility of this clinical entity should be specifically excluded by EEG in any person suffering from prolonged confusion following myelography with water soluble agents.

Reversible depression in Binswanger's disease

The authors describe four elderly patients with Binswanger's disease in whom depression was prominent. Therapy with antidepressant drugs in three patients produced major improvement in psychological and physical functions. The one patient who could not be given an adequate course of antidepressant therapy because of intercurrent illness improved spontaneously after many months. The authors conclude that depression associated with Binswanger's disease is reversible despite persistence of neurological abnormalities. They speculate that this depressive syndrome is an example of organic affective disorder due to diffuse subcortical white matter ischemic lesions of the cerebral hemispheres and discuss the possible neuroanatomical basis of the depression.

48-Kilodalton intermediate-filament-associated protein in astrocytes

We provide evidence that a protein of 48 kilodaltons (KD), recognized by a normal rabbit serum (F2N), is associated with intermediate filaments (IF) of astrocytes both in cell cultures and in situ. Immunofluorescence staining shows that the F2N serum gives a fibrous staining pattern similar to that seen with anti-serum to glial filament protein (GFP), a protein specific for IF of astrocytes, and that both proteins are present in the perinuclear fibrous aggregates of IF produced by treating the cells with colchicine. At the ultrastructural level the gold particles decorating the 48-KD protein are localized in clusters along the IF, whereas the gold particles decorating the GFP are localized on the IF in a linear pattern. This difference in distribution and the fact that the two proteins have different electrophoretic mobilities on SDS gels indicates that the 48-KD protein although associated with IF is different from GFP. The 48-KD protein appears to be a distinct, developmentally regulated intermediate-filament-associated protein (IFAP), different from other IFAPs reported to date and the first IFAP described in astrocytes. Its appearance in late developmental stages when motile astroblasts are changing into nonmotile stellate cells suggests that the 48-KD protein may be involved in cross-linking the GFP-containing IF to provide more tensile strength to the cytoplasm at the expense of flexibility.

Bacteriological quality of raw human milk: effect of storage in a refrigerator

Eighty-seven breast milk samples were obtained from 63 mothers of infants on the neonatal intensive care unit of the Lagos University Teaching Hospital. The samples were cultured for bacteria immediately after collection (0 h) and then stored in a domestic refrigerator from where cultures were repeated at 6-hourly intervals for 24 h. At 0 h, three (3.4%) of the samples were sterile; 56 (64%) grew coagulase negative staphylococci, and one (1.1%) Streptococcus viridans. Thus, 60 (69%) of the samples were either sterile or contained only skin commensals. Twenty-nine (31%) grew potential pathogens--coagulase positive staphylococci in two (2.3%) and mixed growth of staphylococci, coliforms and klebsiella in 25 (28.3%). During the 24 h storage in the refrigerator, bacteria multiplied in 50 and their growth was inhibited in 32 of the samples. But the mean bacterial count at any time during the 24 h was not significantly different from that at the beginning of the storage in the refrigerator. It is proposed that expressed breast milk stored in a domestic refrigerator can be given safely to infants within 24 h of collection if heavy contamination is prevented at the time of collection.

Stability of cefazolin sodium in various artificial tear solutions and aqueous vehicles

The stability of cefazolin sodium reconstituted in four artificial tear solutions, two acetate buffer solutions, phosphate buffer solution, and 0.9% sodium chloride injection was studied. Cefazolin was reconstituted in Tearisol, Isopto Tears, Liquifilm Forte, and Liquifilm Tears; acetate buffer solution at pH 4.5 and pH 5.7; phosphate buffer solution at pH 7.5; and 0.9% sodium chloride injection. The solutions were stored at 4 degrees C, 25 degrees C, and 35 degrees C for seven days. All of the solutions were inspected for particulates, turbidity, color, and odor. Five assay determinations on each of three samples of each formulation were performed using a stability-indicating high-performance liquid chromatographic assay. Cefazolin stability was influenced primarily by pH and storage temperature. Reconstitution of cefazolin sodium in the alkaline tear solutions Isopto Tears and Tearisol and in phosphate buffer solution resulted in particulate and color formation at 25 degrees C and 35 degrees C. Turbidity was noted after cefazolin sodium was reconstituted in Isopto Tears. No color or precipitate formation was evident after seven days at 25 degrees C and 35 degrees C in the formulations of acidic pH containing Liquifilm Tears, Liquifilm Forte, 0.9% sodium chloride injection or acetate buffer solution as the vehicles. The extent of degradation of cefazolin was substantially higher in the formulations of alkaline pH than in those of acidic pH at 35 degrees C and 25 degrees C. All of the formulations retained more than 90% of their initial concentration when stored at 4 degrees C. Cefazolin sodium, when reconstituted in artificial tear solutions with an acidic pH, is stable for up to three days at room temperature.

Calcific valvular aortic stenosis with and without mitral anular calcium

Seventy-six consecutive patients, mean age 66 +/- 9 years (+/- standard deviation), with isolated aortic valve replacement for calcific valvular aortic stenosis (AS) were studied. Mitral anular calcium (MAC) was detected by echocardiography in 45 patients (59%). Patients with MAC were older (p less than 0.01), had greater peak systolic aortic valve gradients (p less than 0.025), lower cardiac indexes (p less than 0.025) and smaller valve areas (p less than 0.05) than patients without MAC. Thirty-three percent of patients (15 of 45) with MAC required permanent pacemaker implantation after aortic valve replacement, compared with only 10% of patients (3 of 31) without MAC (p less than 0.025). During the follow-up of 7 years (mean 3.8 +/- 1.6), 27% of patients (12 of 45) with MAC died from cardiac causes, compared to only 7% (2 of 31) without MAC (p less than 0.025). Thus, patients with AS and MAC are older, have more severe AS, more frequently undergo permanent pacemaker implantation after aortic valve replacement and more frequently die of cardiac causes than patients with AS and no MAC during follow-up.