Concurrent diphtheria and infectious mononucleosis: difficulties for management, investigation and control of diphtheria in developing countries.

We report a case of concurrent diphtheria and infectious mononucleosis in an 11-year-old Brazilian child. Two days after specific treatment for diphtheria was started the patient was discharged following clinical recovery. This case highlights the difficulties in the clinical diagnosis of diphtheria in partially immunized individuals, and for the management and control of diphtheria in developing countries.

Clinical studies of a large family with Wilson's disease.

We have identified 11 individuals with Wilson's disease, members of five sibships within a larger family which was traced through seven generations. Of 206 other family members evaluated for Wilson's disease, none had abnormally low serum ceruloplasmin or copper levels and none had Wilson's disease. There were two documented instances of consanguinity, associated with two of the five affected sibships and four of the 11 affected individuals. The patterns of occurrence of Wilson's disease within the family is consistent with the hypothesis that the disorder is transmitted as an autosomal recessive characteristic. It is likely that the apparently high frequency of disease within the family can be explained solely by the founder effect.

Differential effects of isomeric incorporation of fluorophenylalanines into PvuII endonuclease.

Incorporation of fluorine into proteins has long served as a means of probing structure and function, yet there are few studies that examine the impact of fluorine substitution, particularly at locations distant from the active sites of enzymes. The flexibility of isomeric fluorine incorporation at Phe is used to explore subtle substitution effects on enzyme activity and conformation. The unnatural amino acids o-, m-, and p-fluorophenylalanines were incorporated biosynthetically into the representative PvuII restriction endonuclease. Interestingly, m-fluoro-Phe-PvuII endonuclease exhibits very similar conformational stability to that of the native enzyme, but it exhibits a reproducible, 2-fold higher average specific activity. Given the level of incorporation and the distribution of species, the species of modified enzyme responsible for this increase in specific activity is most likely even faster. Further, moving the fluorine atom from the meta- to the para-position of Phe results in a 4-fold decrease in specific activity and a decrease in conformational stability of 1.5 kcal/mol. Since none of the Phe residues in PvuII endonuclease lies near the DNA recognition or catalytic sites, this differential behavior alludes to the impact of subtle changes in enzyme conformation on endonuclease activity and suggests novel ways to influence catalytic behavior.

Unusual intrauterine objects: potential pitfalls in ultrasonographic identification.

Three cases of echogenic objects in the uterine cavity are reported. These objects had ultrasonographic characteristics of contraceptive intrauterine devices (IUDs) and, in the absence of patients' medical histories, would almost certainly have been wrongly identified as such. The authors demonstrate that noncontraceptive intrauterine objects can mimic IUDs.

PIP: Ultrasonography has been used effectively to evaluate the endometrial cavity in search of a missing IUD. Specific ultrasonographic features of IUDs include posterior acoustic shadowing, type-specific morphologic features, and entrance-exit reflection. This article presents 3 cases of echogenic objects in the uterine cavity. In the 1st case, the object was osseous tissue from an incomplete septic abortion. In the 2nd case, the object was a polyethylene stent which had been used in a left cornu reimplantation. The 3rd object was a cotton swab. Ultrasonographic features in all 3 cases were similar to those of IUDs. The medical history of each patient made correct interpretation of the ultrasonographic images possible. In the absence of such histories, these objects would have been wrongly identified as IUDs.

Fetal elevation: a new technique for placental localization in the diagnosis of previa.

The diagnosis of previa is made with ultrasound when the placenta is seen to cover the internal os. The technique of fetal elevation is a simple procedure that facilitates visualization of the internal os and its relation to the placenta. The safety of this technique is demonstrated in a large series of patients.