Effects of D-penicillamine on neuromuscular transmission in rats

Treatment of patients with D-penicillamine (D-P) has been associated with a syndrome similar to myasthenia gravis (MG). To explore this association, we examined the effects of D-P on neuromuscular transmission in rat muscle. In the first experiment, bath-applied D-P had no significant effect on either miniature endplate potential (MEPP) amplitude or action potential (AP) amplitude. Endplate potential (EPP) amplitude and spontaneous MEPP frequency decreased significantly at concentrations approximately 40 times the maximum human therapeutic level. In the second experiment, rats receiving D-P by daily injections for 33 to 37 days did not differ from controls in any of the measured electrophysiologic characteristics. Electron microscopy of muscle endplates from rats treated with D-P showed no evidence of degeneration or simplification. In all cases, thymus histology by light microscopy was normal, and no antireceptor antibodies were found. Thus, D-P has a mild direct presynaptic effect on neuromuscular transmission at high concentrations, but this effect is too small to account for the weakness seen in the myasthenia-like syndrome in humans.

Short-term effects of prednisolone on neuromuscular transmission in normal rats and those with experimental autoimmune myasthenia gravis

Electrophysiological investigations of the effects of bath-applied prednisolone at the neuromuscular junction were performed in muscles from normal rats and rats with experimental autoimmune myasthenia gravis (EAMG). In muscles from both groups, prednisolone reversible and significantly depressed the amplitudes of minature end-plate potentials (MEPPs), end-plate potentials (EPPs) and indirectly elicited action potentials (APs) without affecting resting membrane potentials. Prednisolone also caused a significant reduction in EPP rise time to peak and half-decay time while markedly increasing MEPP frequency and AP rise time to peak and duration. These effects were shown to be dose-dependent. The percentage decrease in amplitude after prednisolone perfusion was similar for EPPs and MEPPs, indicating that the depressive effect of prednisolone at the junction is postsynaptic. In all of the parameters studied, the percentage effect of prednisolone was the same in EAMG and normal preparations. No stimulus-linked repetitive EPPs or APs were observed after prednisolone. It is concluded that prednisolone has a depressive effect on neuromuscular transmission, but that this occurs only at high concentrations of the drug which are not achieved during the treatment of myasthenia gravis.

Dextran 40-containing incubation media: effect on lens electrolyte and water balance

The effect of dextran 40 on lens swelling and electrolyte balance in lenses stressed by incubation in Ca++-free media was studied. Dextran 40 substantially inhibited lens swelling, Na+ gain, and K+ loss caused by six-hour incubation in Ca++-free media. After an additional 12-hour incubation in Ca++-enriched media, the water and electrolyte balance in the dextran 40-incubated group was essentially the same as that of lenses that were never exposed to a Ca++-free media. Those lenses that were not incubated in dextran 40 demonstrated significant residual lens swelling and electrolyte imbalance. It is concluded that dextran 40, by virtue of its oncotic effect, inhibits colloidal osmotic swelling and exerts a protective effect on lens function under a stress situation.

Single-fiber electromyography in myasthenia gravis

One-hundred-sixty single-fiber EMG studies of the extensor digitorum communis muscle were performed on 127 patients with myasthenia gravis; 131 demonstrated defective neuromuscular transmission. Jitter determinations in the biceps, deltoid or frontalis muscles increased the diagnostic yield significantly. Evoked-potential EMG studies were abnormal in less than 50 percent of patients in whom they were performed. The most sensitive criterion of abnormality was the percentage of fibers with increased jitter; the sensitivity of the test was enhanced, however, if the mean jitter of the tested muscle was also used as a criterion of abnormality. Since increased jitter may also be seen in primary muscle and nerve disease, these disorders must be excluded by other means before diagnosing myasthenia gravis on the basis of the single-fiber studies.

Bronchiolo-alveolar carcinoma: a correlative clinical and cytologic study

From 1970 to 1977, 101 patients with bronchiolo-alveolar carcinoma were admitted to the Toronto General Hospital. Cytology preparations from 97 patients were reviewed and analyzed in correlation with biologic behavior of the tumours. The value of cytologic diagnosis was reassessed. It appears that routine cytology methods were of limited value in the investigation of patients with a peripheral solitary tumor and therefore, percutaneous fine needle aspiration with positive results in 92% of cases examined, was the only useful cytologic examination for this type of lesion. For multicentric tumors, routine cytology methods achieved positive results in 87.9% of cases and fine needle aspiration 100%. Based on cytomorphologic features, bronchioloalveolar carcinoma can be subclassified into three types: secretory, nonsecretory and poorly differentiated. In this series, 84% of solitary tumors were secretory or nonsecretory type with favorable prognosis, and 16% of solitary tumors were poorly differentiated type with poor prognosis. 55.2% of multicentric tumors were poorly differentiated type and 77.3% of multicentric tumors showed positive lymph nodes at surgery. Our results demonstrate that patients with multicentric or poorly differentiated tumors had poor prognosis.

Neonatal experimental autoimmune myasthenia gravis

Neonatal rats born of and nursed by mothers immunized with Torpedo acetylcholine receptor protein developed a defect of neuromuscular transmission as indicated by reduced miniature endplate potential amplitudes. It is likely that antibodies to the Torpedo receptor protein were passively transferred to the neonates in the milk. With the exception of the route of transfer, this neonatal form of experimental autoimmune myasthenia gravis appears to be similar to its human counterpart, and thus can serve as an experimental model.

Five month extrauterine survival in a female triploid (69,XXX) child

The case of a (69,XXX) triploid infant who survived 160 days is reported. Previously, the longest survival of a non-mosaic triploid had been 9 days. Possible reasons for this extensive survival are discussed.

A simple body weighing machine

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Experimental autoimmune myasthenia gravis in rats. Modification by thymectomy and prednisolone

In rats immunized with purified acetylcholine receptor protein (AChRP) from Torpedo electroplax, a defect of neuromuscular transmission physiologically identical to that seen in myasthenia gravis developed. The most sensitive index of the neuromuscular blockage was miniature end-plate potential (MEPP) amplitude. As early as 24 hours after inoculation with AChRP, the thymus showed reactive changes that are probably nonspecific. Removal of the thymus before or within three days after immunization delayed, but did not prevent, development of reduced MEPP amplitude. Prednisolone given within 35 days after immunization produced reversal of MEPP reduction within 24 hours, but had no such immediate effect when given 15 days later. It is probable that prednisolone acted by reducing the immunologic responsiveness of the animals during the developing phase of the defect of neuromuscular transmission.

Myotonia congenita with painful muscle contractions

We present a family with dominantly inherited myotonia congenita and painful, electrically silent muscle contractions after exertion. In two family members, painful muscle contractions occurred coincident with hypothyroidism, and improved after thyroid replacement therapy. It is probable that this family represents a disease that is similar to but distinct from the dominant form of myotonia congenita.

Intravitreal antibiotic injection and vitrectomy in acute bacterial endophthalmitis

Two days after an unplanned extra-capsular cataract extraction with sector iridectomy, a patient showed typical signs of bacterial endophthalmitis. Vitreous and aqueous were aspirated for culture, and gentamicin and dexamethasone were injected. Twenty-four hours later, after isolation of Staphylococcus epidermidis, a vitrectomy to remove the central vitreous was done. Postoperatively, vision progressively improved; at the last review nine months after vitrectomy, visual acuity was 20/50.

The toxicity of intravitreal whole blood and hemoglobin

To determine the toxic effect of whole blood and hemoglobin on the retina, volumes of autogenous blood varying between 0.3 and 1.5 ml and various hemoglobin concentrations were injected intravitreally into speciosa monkeys. Electroretinograms were performed at the outset of the experiment and immediately before sacrifice. After six weeks the animals were killed and the eyes were processed for histologic and electron microscopic examination. Three intravitreal injections of 0.3 ml of autogenous blood administered at one-month intervals or one injection of 22.4 mg of hemoglobin did not produce a toxic effect on the retina demonstrable by light or electron microscopic examination or electroretinography. Intravitreal injection of more than 0.6 ml of whole blood or 40 mg of hemoglobin produced definite toxic effects histologically and electroretinographically. The damage found histologically correlated well with the degree of hemosiderin deposition. Explosive lesions produced by xenon are photocoagulation to induce moderate vitreous hemorrhage failed to produce toxic doses of blood within the eye. In humans undergoing vitrectomy to remove vitreous hemorrhage, the amount of whole blood recovered from vitrectomy fluid was considered nontoxic, except when the patient had massive vitreous hemorrhage or intraoperative bleeding.

The vitrophage in ocular trauma. Report of 15 cases

Fifteen patients underwent a pars plana approach vitrectomy and membranectomy after acute and chronic injury. In all cases the lens fragments, hemorrhage, and secondary membranes were removed restoring clarity to the ocular media. In two cases the final visual acuity was limited by preexisting retinal injury. The advantages of pars plana approach are the small incision and minimal ocular manipulation during surgery. In the presence of retinal injury, diathermy during the procedure or photocoagulation within 24 hours is also indicated.

Intravitreal injection of vancomycin in experimental staphylococcal endophthalmitis

Toxicity, clearance, and therapeutic effectiveness of intravitreal vancomycin hydrochloride injection in experimentally induced staphylococcal endophthalmitis were evaluated. Vancomycin was found to be nontoxic in a single, 1 mg/0.1 ml intravitreal dose. Therapeutic levels of vancomycin were present in the vitreous for over 72 hours and in the aqueous during a period from 6 to 48 hours after injection. Injection of a methicillin-resistant Staphylococcus aureus produced a panophthalmitis in our systemically treated controls, whereas in the rabbits treated by intraocular injection, the course of the infection was significantly altered.