Hypocomplementemia is an important marker for the presence of IC-mediated disease and can be used to assess disease activity. However, in interpreting the clinical significance of hypocomplementemia, the following must be kept in mind: 1) There are numerous non-immunologic conditions that also can cause hypocomplementemia. Furthermore, some of these conditions can cause a multisystem disease that, along with the hypocomplementemia, can closely resemble an IC-mediated systemic vasculitis. Furthermore, these nonimmunologic conditions that lower serum complement levels can complicate the course of patients with inactive IC-mediated disease, spuriously indicating that the disease is active. The most relevant of these differential diagnostic problems are listed in Table 2. 2) There are a few conditions (for example, pregnancy) that can raise serum complement levels, thereby possibly obscuring the presence of a disorder (such as, active SLE) that is lowering complement levels. 3) There are some conditions that might be expected to lower serum complement levels, because of their effect on protein metabolism, but do not. Nephrotic syndrome, and moderately poor nutrition are examples. All of these factors should be considered when interpreting results of serum complement levels in a given patient.

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The apical and principal segments of the bovine acrosome contain a stable matrix complex that is bound to the outer acrosomal membrane and exhibits hydrolase-binding activity. The present study was undertaken to determine whether the outer acrosomal membrane-associated matrix complex (OMC) is composed of a unique set of acrosomal proteins and to define its fate during both capacitation and the acrosome reaction. A purified OMC fraction was isolated from ejaculated spermatozoa, and one polypeptide of 32 kDa (OMC32) was purified to homogeneity and used for N-terminal sequence analysis and preparation of monospecific antisera. Immunofluorescence staining of sperm with anti-OMC32 demonstrated that the polypeptide localized specifically to the apical and principal segments of the acrosome. Immunoelectron microscopy further revealed that OMC32 was restricted to the stable matrix assembly and was not associated with the inner acrosomal membrane or the equatorial segment. Immunoblot analyses of sperm lysates and of the purified OMC fraction revealed that anti-OMC32 recognized an antigenically related family of polypeptides between 38 and 19 kDa. These polypeptides exhibited no size processing during capacitation or the acrosome reaction, and they were not released during the acrosome reaction but remained in the particulate cell subfraction, associated with the hybrid membrane complex. N-terminal sequence analysis of OMC32 indicated a structural relationship to the SP-10 polypeptide family of human and baboon spermatozoa. The potential function of the OMC complex and differences in the intraacrosomal distribution of bovine OMC32-related polypeptides from that reported for acrosomal SP-10 polypeptides in other species are discussed.

Prune belly syndrome (PBS), a triad consisting of abdominal musculature hypoplasia, urinary tract malformations, and cryptorchidism, is frequently associated with other congenital malformations. Although it is acknowledged that gastrointestinal (GI) malrotation and mesenteric anomalies are frequent in PBS, other GI anomalies are generally considered to be exceedingly rare. Here we describe 3 autopsy cases with severe malformations of both midgut and hindgut derivatives and review the world literature to evaluate the spectrum of GI malformations associated with this syndrome. The relatively high frequency of distal stenoses and atresias suggests that the anomalous mesenteric attachments may predispose to prenatal volvulus and subsequent anatomic bowel obstruction. Postnatal volvulus is also occasionally observed. Infants with PBS also appear to be at a higher risk for persistence of the common fetal cloaca.

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