Influence of long-term aldose reductase inhibitor therapy on autonomic dysfunction of urinary bladder, stomach and cardiovascular systems in diabetic patients

The effects of the aldose reductase inhibitor (ARI) sorbinil (250 mg/day) were tested in an open-label pilot study over 1 year, in eight diabetics with peripheral neuropathy, seven of whom had symptomic autonomic neuropathy (AN). Autonomic function studies of the urinary bladder, stomach and cardiovascular system were performed at baseline, 6 and 12 months. Six patients reported improvement in symptoms of AN by 6 months which was maintained or further improved by 12 months. Bladder sensation, as measured by cystometrographic parameters, improved at 6 months (P less than 0.02- less than 0.04), but by 12 months had reverted to baseline. Residual urine volume decreased at 6 months (P less than 0.06) and 12 months (P less than 0.06). Vagally mediated gastric acid secretion improved at 6 months (P less than 0.06); the subgroup of patients with subnormal secretion showed improvement to the normal range at 6 months (P less than 0.03). Gastric emptying of solid food was normal in six of eight subjects and showed no significant change at 6 months. Both patients with delayed emptying normalized. No change in beat-to-beat variability in heart rate with respiration was noted. Resting minimum heart rate decreased at 12 months (P less than 0.05). Glycohemoglobin levels showed no statistically significant changes. No toxic reactions were observed. These data suggest a beneficial effect of ARI treatment on symptomatic and asymptomatic manifestations of diabetic autonomic neuropathy and indicate a need for large controlled trials.

Developmental regulation of DNase I-hypersensitive sites in Dictyostelium discoideum

We have studied two regions of Dictyostelium discoideum chromatin and identified several DNase I-hypersensitive sites in these regions. One of these sites is located about 300 to 500 bases upstream of the transcriptional start site of a gene that is expressed at all stages of development. This site is present in both vegetative cells and postaggregation cells. Another hypersensitive site is associated with a gene that is expressed only after the multicellular stage. This site is located about 400 bases upstream of the start site, and it is present only in postaggregation cells. Thus, much like higher eucaryotes, D. discoideum contains DNase I-hypersensitive sites that may be involved in the regulation of the genes with which they are associated.

Natural cell-mediated cytotoxicity to cells infected with infectious bovine rhinotracheitis virus

Cell-mediated cytotoxicity against viral-infected cells was demonstrated in a 6-hr 51Cr release assay. Peripheral blood mononuclear leukocytes from both infectious bovine rhinotracheitis virus (IBRV)-infected and noninfected cattle exhibited preferential lysis against IBRV-infected primary bovine embryonic kidney (BEK) cells compared to cells infected with pseudorabies virus and noninfected BEK cells. Addition of specific antibody to the assay did not enhance cytotoxicity. The effector cell was a nonadherent cell which was either spontaneously enriched or generated during in vitro cultivation. Maximal cytotoxic activity was detected in peripheral blood mononuclear cells cultured for 3 to 5 days. Several factors affected the magnitude of cytotoxicity during the assay: target cell type, concentration of viral inoculum, duration of effector and target cell contact. It is suggested that target cell lysis was a form of natural cell-mediated cytotoxicity mediated by a cell which has different characteristics from the typical human and murine NK cell.

Directional control of site-specific recombination by bacteriophage lambda. Evidence that a binding site for Int protein far from the crossover point is required for integrative but not excisive recombination

Phage lambda controls its integration and excision by differential catalysis of the forward and reverse reactions. The lambda Int protein is required for both directions, but Xis for excision only. To investigate the substrate requirements for directional control, we have characterized two mutations of the phage attachment site that are defective in integrative but not excisive recombination. Both of these mutations produce the same base change in the P'3 binding site for Int protein 79 base-pairs from the center of the crossover region for site-specific recombination. We infer that differential utilization of this distant binding site is crucial for directional control of recombination.

Monoclonal antibodies to cystic fibrosis antigen

A series of monoclonal antibodies has been prepared against a granulocyte antigen previously shown to be present in the serum of individuals homozygous or heterozygous for the cystic fibrosis (CF) gene. The specificity of the monoclonals was established by their ability to remove the antigen (CF antigen) from serum. The monoclonals defined at least two epitope regions on CF antigen, thus permitting the establishment of a two-site sandwich enzyme-linked immunosorbent assay (ELISA). Using the ELISA significant differences in levels of CF antigen were demonstrated in serum samples from CF homozygotes, CF heterozygotes and normal controls.

Common acylcarboxypeptidase A intermediates for ester substrates containing different cleaving alcohols

In the carboxypeptidase A-catalyzed ester hydrolysis of the trans-alpha-(benzoylamino)cinnamoyl derivatives of both L-mandelate and L-beta-phenyllactate, kcat stands for the breakdown of an additional enzyme-substrate complex (ES'). The pH dependence of kcat indicates that ES' is the anhydride acylcarboxypeptidase A formed by the nucleophilic attack of Glu-270 for both of the ester substrates. Furthermore, the very similar kcat values for the two ester substrates which share a common acyl moiety strongly suggest that common acylenzyme intermediates are involved, whose breakdown process is little affected by the cleaved alcohol portions. This provides the most direct evidence that has been reported for the nucleophilic mechanism of the carboxypeptidase A action.

A monoclonal antibody-based immunoassay for human lactoferrin

Monoclonal antibodies against human lactoferrin define at least 3 and possibly as many as 6 different epitopes. A sandwich enzyme-linked immunoassay, using monoclonals against different epitopes, has been optimised for the measurement of serum lactoferrin. In 35 samples from healthy adults the mean lactoferrin content of serum from blood clotted overnight was 0.54 +/- 0.26 micrograms/ml.

Dictyostelium transposable element DIRS-1 has 350-base-pair inverted terminal repeats that contain a heat shock promoter

DIRS-1 is a 4.7-kilobase-pair repetitive and apparently transposable Dictyostelium genetic element that is transcribed during differentiation or after heat shock. The terminal regions of DIRS-1 are inverted repeats of 330 base pairs. The repeats are highly conserved both within a given element as well as between different members of the family (less than 10% divergence). At the distal end of all left repeats is a 32-nucleotide sequence composed almost entirely of A and T residues. In addition to this 32-base A + T sequence, the distal region of all right repeats is extended by a 28-base-pair A + T-rich sequence that is identical in all copies. The sequences flanking each DIRS-1 sequence are completely dissimilar, and there appears to be no duplication of the genomic DNA sequence at the presumed point of DIRS-1 insertion. The terminal repeats can also be found interspersed in the genome independently of the complete element. In addition, the terminal repeats carry a 15-nucleotide sequence that greatly resembles the Drosophila consensus heat shock promoter and may be involved in the transcriptional induction of the DIRS-1 sequences.

A repetitive and apparently transposable DNA sequence in Dictyostelium discoideum associated with developmentally regulated RNAs

Dictyostelium discoideum AX3 genomic DNA contains about 40 copies of a 4.5 Kb sequence. Each has the same restriction map, suggesting that they are all very similar. The sequences are scattered throughout the genome, and each of the six representative copies we cloned have different flanking sequences. Partial fragments of the 4.5 Kb sequence also are scattered throughout the genome. The DNA sequences flanking the 4.5 Kb repetitive sequences are different in different strains of Dictyostelium suggesting that the 4.5 Kb sequence is a transposable element. Each sub-region of this 4.5 Kb sequence is associated with a large number of mRNAs, all of which are developmentally regulated, but whose function is not known.

Transcriptional control of gene expression during development of Dictyostelium discoideum

During development of the cellular slime mold Dictyostelium discoideum, approximately 2,000 to 3,000 regulated mRNAs are induced when amoebae enter multicellular aggregates. We used in vitro transcription in isolated nuclei to follow the synthesis of individual mRNA precursors during development; these were quantitated by hybridization to cloned cDNAs or genomic DNAs. Those RNAs that are present at all stages of development--the common RNAs--were transcribed by nuclei from cells at all stages of development. By contrast, those RNAs that are present only after cells begin to aggregate--here called aggregation stage RNAs--were transcribed only by nuclei from cells at the aggregation and postaggregation stages of development. The temporal pattern of in vitro transcription correlated well with the time course of accumulation of different aggregation stage mRNAs. Continued expression of aggregation stage genes normally depends upon cell-to-cell contact or cyclic AMP (cAMP); when cells are disaggregated, the regulated mRNAs are rapidly and specifically degraded. When cAMP is subsequently added to the disaggregated cells, most of the mRNAs reaccumulate. We show here that disaggregation reduced 2- to 10-fold the relative transcription of several aggregation stage RNAs, whereas addition of cAMP to disaggregated cells reinduced the level of regulated gene transcription to values approximating those found in normal postaggregation cells. These results indicate that a representative set of Dictyostelium aggregation stage genes are under transcriptional control; both the transcription and the stability of these mRNAs require either continued cell-to-cell interactions or cAMP.

Synthesis and stability of developmentally regulated dictyostelium mRNAs are affected by cell--cell contact and cAMP

Postaggregation Dictyostelium discoideum cells contain 3000 mRNA species that are absent from preaggregation cells; these aggregation-dependent sequences comprise 30% of the mass of mRNA in these cells. We show that the synthesis and stability of these regulated mRNA sequences are affected by both cell--cell contact and cAMP. Three independent assays are used to quantitate these mRNAs: in vitro translation followed by two-dimensional gel analysis of the protein products; hybridization of gel-separated RNAs to cloned DNAs; and hybridization of mRNA to a cDNA probe specific for the population of regulated sequences. In postaggregation cells, the half-life of both the developmentally regulated mRNAs and the constitutive mRNAs present throughout growth and differentiation is the same--about 4 hr. Following disaggregation, all of the late mRNA sequences are degraded and decay with a half-life of 25 to 45 min. The constitutive species are unaffected; 2.5 hr after disaggregation, the ratio of late to constitutive mRNAs is about 6% that of normal plated cells. Addition of cAMP to cells that have been disaggregated for 2.5 hr (or longer) restores the level of most late mRNAs within 3 hr. We conclude that cAMP stimulates the synthesis of these mRNAs and may also act to stabilize them in the cytoplasm. This effect of cAMP is dependent on the cells having been in contact with other cells; cAMP has no effect on the levels of mRNA in suspension-starved, aggregation-competent cells that have never formed cell--cell aggregates.

Isolation and characterization of nuclear ribonucleoprotein complexes from Drosophila melanogaster

The isolation of total nuclear ribonucleoprotein particles from Drosophila melanogaster embryos, using a pH 8.0, 01 M NaCl extraction of purified nuclei, is described. When the extract is fractionated on isokinetic sucrose gradients, at least six major classes of nuclear ribonucleoprotein complexes, differing in RNA and protein content as well as sedimentation behavior, are observed. The two largest complexes are preribosomal complexes. The remaining four major classes of RNPs sediment at roughly 6S, 8S, 12S and 30S. A minor class at 17S is also observed. The 30S fraction is 200-250 A in width and appears to be analogous to the mammalian monoparticle. It is composed primarily of polypeptides at about 36 000 and 37 000 daltons, along with 1-2 kilobase RNA fragments. The 6S, 8S and 12S complexes contain a few discrete small nuclear RNAs from 80-600 bases in length, along with a small number of polypeptides, about 50 000, 52 000, 56 000 and 75 000 daltons. These novel complexes are of the order of a 100 A in width (60-120 A range).

Selection and analysis of cloned developmentally-regulated Dictyostelium discoideum genes by hybridization-competition

We describe a new technique for selection of cloned gene segments which are expressed preferentially at one developmental stage but at a relatively low level. A nitrocellulose filter replica of plaques of lambda phage which contain approximately 8 KB inserts of genomic DNA is prepared; it is hybridized with a small amount of [32p] labeled mRNA prepared from one developmental stage, in the presence of a several-hundred fold excess of competitor RNA from a different stage. We show that clones of Dictyostelium nuclear DNA which form hybrids under these conditions indeed encode developmentally regulated mRNAs. Our previous analysis of Dictyostelium discoideum differentiation indicated that transcripts from about 12% of the genome appear in mRNA at one defined stage of differentiation - the formation of cell-cell aggregates. A number of our new clones are novel, in that they encode multiple discrete mRNA species all of which accumulate only at the cell aggregate stages; others encode one or more mRNAs which appear at the tight aggregate stage and also one or more which are present throughout differentiation. These latter clones, in particular, would be difficult to identify using other selection techniques.