Selective secretion of annexin 1, a protein without a signal sequence, by the human prostate gland

Annexins are primarily intracellular proteins as would be predicted from their lack of hydrophobic signal sequences. However, we now report that the human prostate gland selectively secretes high concentrations of annexin 1 (also called lipocortin 1 and p35) and a proteolytic cleavage product, des1-29-annexin 1, into seminal plasma. Secreted annexin 1 had a blocked amino terminus and was structurally indistinguishable from intracellular annexin 1. Although annexin 1 and the structurally related protein, annexin 4, co-localized to many of the same cells of the ductal epithelium of the prostate, annexin 4 was not secreted. Thus, the secretion of annexin 1 appears to involve a highly selective mechanism that does not involve targeting to the endoplasmic reticulum by a hydrophobic signal sequence.

Maintenance of local cerebral blood flow after acute neuronal death: possible role of non-neuronal cells

In brain, a major factor regulating local perfusion is local neuronal activity. However, we have recently discovered that, in rat, five days after selective neuronal destruction in the parietal cortex by local microinjections of the excitotoxin ibotenic acid, local cerebral blood flow, within the lesion, remains in the normal range. We studied whether proliferating non-neuronal cells and/or local changes in microvascular density participate to maintain local cerebral blood flow. Rats were anesthetized (halothane 1-3%), ibotenic acid (10 micrograms in 1 microliter) was locally microinjected in a restricted region of the parietal cortex, and animals were allowed to recover. Three, five, seven, 11, 30 days later local cerebral blood flow was measured autoradiographically under chloralose anesthesia (40 mg/kg, s.c.) by the [14C]iodoantipyrine technique. Cellular density or microvascular area were determined on sections stained with Thionine or processed for the endothelial marker alkaline phosphatase, respectively. Local neurons were destroyed by 24 h after microinjections of ibotenic acid. However, from three to 11 days after lesion local cerebral blood flow was unchanged (P greater than 0.05; n = 5), thereafter declining so that by 30 days blood flow was 48 +/- 6% of control (P less than 0.05; n = 5). Cellular density increased within the lesion by 17.5-fold at seven to 11 days (P less than 0.01) and declined to a 11.7-fold elevation above control at day 30 (P less than 0.01). New cells consisted of macrophages, endothelium and glial fibrillary acidic protein-positive astrocytes. The microvascular area increased 4.2-fold from three to 11 days (P less than 0.01). The patency of the presumably newly formed vessels was determined by the presence of intravascular red blood cells, which were revealed histochemically. The area occupied by red blood cells within cerebral microvessels, in contrast to microvascular area, did not increase until seven days after lesion, reaching a 3.2-fold increase at 11 days. Thus within the lesion, local cerebral blood flow remains constant during the phase in which cellular and microvascular density increases. The presumably newly formed vessels cannot contribute to maintain local cerebral blood flow since during this phase they are not patent; rather patency develops coincident with the decline in local cerebral blood flow. We conclude that non-neuronal cells, most likely activated macrophages, may be an important factor regulating local cerebral perfusion, after acute neuronal death.

Glutamate in the spinal sympathetic intermediolateral nucleus: localization by light and electron microscopy

Glutamate immunoreactivity was examined in the sympathetic intermediolateral nucleus (IML) of the thoracic spinal cord using an antibody (Hepler et al., J. Histochem. Cytochem., 36 (1988) 13-22) to hemocyanin-conjugated L-glutamate and the peroxidase-antiperoxidase (PAP) technique. Glutamate labeling was seen in punctate varicosities throughout the IML, in IML neurons and their dendritic processes extending into the lateral funiculus, and diffusely in the IML neuropil. Glutamate labeling was unaffected by preabsorption of the antibody with a conjugate of L-aspartate (100 micrograms/ml) to bovine serum albumin (BSA), but was abolished by similar treatment with a conjugate of L-glutamate (1.7 microgram/ml) to BSA. Glutamate immunoreactivity in the IML was eliminated caudal to T3 spinal transection, while that in the dorsal horn was preserved. Ultrastructural examination of the IML revealed that glutamate was localized within round clear vesicles in axon terminals ranging in diameter from 0.6 to 2.5 microns, and containing several mitochondria, but no dense-core vesicles. Glutamate-containing terminals made primarily asymmetric synapses on small dendrites of IML neurons. These synapses were usually enveloped by processes of astrocytic glia which could also contain glutamate immunoreactivity. The findings provide an anatomic substrate for glutamatergic excitation of sympathetic nerve discharge through a descending spinal pathway terminating in the IML. These data support the hypothesis that sympathoexcitation elicited by stimulation of the rostral ventrolateral medulla may be mediated by a direct glutamatergic pathway to the IML.

Evaluation of the Du Pont HERPCHEK herpes simplex virus antigen test with clinical specimens

The HERPCHEK herpes simplex virus (HSV) antigen test (Du Pont, Billerica, Mass.) is a biotinstreptavidin-amplified enzyme-linked immunoassay for the detection of HSV antigen directly in clinical specimens. In a total of 200 mucocutaneous specimens, predominantly lesions from nongenital sites, HERPCHEK had a sensitivity of 90% and a specificity of 99% compared with the shell vial tissue culture method which uses primary rabbit kidney cells. Five false-negative results by HERPCHEK were found with specimens that contained a low percentage of positive cells by the direct immunoperoxidase stain used in a tissue culture method (1 to 9%). The absorbance values of the clinical specimens by the HERPCHEK test do not correlate well with the percentage of positive cells. Our results indicate that the HERPCHEK HSV antigen test, when performed with specimens from lesions, is a sensitive and specific test as compared with shell vial culture.

Concurrent determination of hepatic bioavailability of salicylamide by three techniques in the dog

Three methods of measuring hepatic first-pass metabolism of salicylamide in dogs that had undergone portacaval transposition were compared. The drug in both its radiolabeled (0.74 MBq) and unlabeled (20 mg/kg) forms was infused concurrently into forelimb and hindlimb veins, respectively. Because of the transposition, drug from the hindlimb is subject to first-pass metabolism in the liver. Bioavailability is a complementary measure of the extent of this metabolism. The three methods of determining bioavailability were continuous withdrawal of blood to determine the ratio of the areas under the plasma concentration versus time curves, ratio of specific activities in plasma after all the drug had been administered, and the conventional method, measurement of the ratio of areas determined from sequential plasma concentrations. The three techniques were found to give virtually identical values for bioavailability. Each method has its own advantages, limitations, and possible applications. The continuous withdrawal technique is potentially most applicable for drugs with short half-lives. The ratio of specific activities may be the preferred method for drugs with long half-lives. The conventional method is limited by the number of samples needed, but is potentially useful under those conditions in which data following test and intravenous routes of administration are available.