Chronic measurement, using a Doppler probe, of uterine artery flow in the gravid guinea-pig

A chronic animal model is described which permits for the first time the continuous measurement of uterine artery blood flow velocity in the pregnant guinea-pig by using a miniaturized Doppler flow probe. Preliminary validation revealed that alterations in actual blood flow are directly and proportionally related to the change in the Doppler shift (r = 0.984) from 0 to 100 ml/h. The velocity signal baseline was as stable as that of systemic blood pressure. Depending upon the individual animal's flow velocity, a deviation of 2-5% from baseline was statistically significant. With experience, greater than 90% of preparations were successful and a 30-day interval was often available for study. Uterine artery flow velocity increased steadily between 45 and 55 days of gestation. Instrumentation did not result in fetal growth retardation. A reduction in flow velocity occurred during general anaesthesia using ketamine and the antianxietal xylazine. In agreement with the reports of other investigators using a different model, both hydralazine and angiotensin II increased uterine blood velocity and adrenaline reduced it.

Functional domains of the nicotinic acetylcholine receptor

The nicotinic acetylcholine receptor is a multisubunit, membrane-spanning protein that contains a gated, cation-conducting channel. Our approach to the understanding of the function of this receptor in molecular terms has been to locate its functionally significant sites in the sequences of its subunits and in its three-dimensional structure. In addition, we have tried to correlate transitions in the properties of these sites with functional transitions of the receptor. On binding acetylcholine, the nicotinic acetylcholine receptor enters at least two transient states, the open state and the rapid-onset desensitized state, and, in the continued presence of agonist, finally subsides into the slow-onset desensitized state. The transitions of the receptor between these various states are susceptible to regulation by acetylcholine and its congeners acting at one type of site and by a broad class of noncompetitive inhibitors (NCIs), including local anesthetics, acting at other sites. The chain composition of the receptor is alpha 2 beta gamma delta. The two acetylcholine binding sites are on the alpha chains, and two residues contributing to these sites, Cys-192 and Cys-193, have been identified. Furthermore, these adjacent Cys residues are cross-linked by a disulfide bond. In the quaternary structure of the receptor, the chains appear to be arranged in the order alpha gamma alpha beta delta around a central channel. Both the alpha and beta chains contribute to functionally significant NCI binding sites. The addition to receptor-rich membrane from Torpedo electric tissue of agonists (but not competitive antagonists) renders these NCI sites susceptible to photolabeling by the NCI quinacrine azide (QA). Furthermore, this susceptibility is transient, arising in milliseconds and subsiding in hundreds of milliseconds. These transiently susceptible sites are protected by other NCIs against photolabeling by QA. The time-course of the susceptibility and its dependence on agonist-concentration suggest that it might be the transient, rapid-onset desensitized state of the receptor that is most susceptible to photolabeling by QA.

Stereospecific antibodies to propranolol

The beta-adrenergic antagonist propranolol was activated through its side chain, coupled to bovine serum albumin, and injected into BALB/c mice. After fusion of the splenocytes from these immunized mice with the NS-1 myeloma cell line, two hybridomas, producing monoclonal anti-propranolol antibodies, were isolated. Clone P-49 was monospecific for propranolol, with a significant preference for the 1-stereoisomer, as compared to the d form. On the other hand, clone P-28 cross-reacted with alprenolol as well as some other beta-antagonists. Both classes of antibodies competed with A431 epidermoid carcinoma beta 2-adrenoceptors for the binding of [3H]propranolol. When ascites cells from clone P-28 were fixed with glutaraldehyde, the anti-propranolol monoclonal antibody became cell bound. These cell-bound P-28 antibodies bind propranolol and other beta-adrenergic ligands with a similar ranking order to the soluble monoclonal antibody. The cell-bound antibody displayed a 5-fold higher affinity towards 1-propranolol than the soluble monoclonal antibody. The practical implications of these findings are discussed.

Monoclonal antibodies embedded in their hybridoma cells: an immunodiagnostic concept

Aldehyde fixation of hybridoma cells during active production of monoclonal antibodies (MAbs) resulted in the formation of an insoluble phase because a large number of immunologically active antibody molecules were immobilized on the fixed hybridoma cells. Such MAb preparations specific to large protein molecules and small haptens were used for the development of a homogeneous immunoassay concept.

(o- and p-Nitrobenzyloxycarbonyl)-5-fluorouracil derivatives as potential conjugated bioreductive alkylating agents

A series of (o- and p-nitrobenzyloxycarbonyl)-5-fluorouracil derivatives were synthesized by reacting o- or p-nitrobenzyl chloroformate with 5-fluorouracil in the presence of triethylamine in DMF or Me2SO. The reductive activation of these agents was hypothesized to generate a reactive methide and 5-fluorouracil, two components that are capable of synergistic interaction through complementary inhibition. Measurement of the surviving fractions of EMT6 tumor cells treated with these agents in culture under conditions of hypoxia and aerobiosis resulted in equal cell kill regardless of the state of oxygenation. One of the synthesized agents, 3-(p-nitrobenzyloxycarbonyl)-5-fluorouracil (4), appeared to be superior to 5-fluorouracil in prolonging the survival time of mice bearing intraperitoneal implants of the P388 leukemia and Sarcoma 180.

A systematic approach for detecting high-frequency restriction fragment length polymorphisms using large genomic probes

Thirteen phage clones containing low-copy sequences were isolated from a human DNA library and tested for their ability to detect restriction fragment length polymorphisms (RFLPs). Reported are the RFLPs revealed with each clone, all found in frequencies useful for linkage studies. Cytological data are available for five of the 13 clones, with regional assignments made for three of the markers by in situ hybridization. It is concluded that phage clones containing large unique DNA inserts detect multiple RFLPs with high efficiency. An analysis of the relative efficiency of 20 restriction enzymes for detecting single nucleotide changes is discussed by comparing the observed data to those expected on the basis of recognition and potential site frequencies, as computed from the dinucleotide distribution. Finally, in an effort to facilitate linkage studies using polymorphic DNA sequences, experiments were made with pools of probes from various sources.

Dysphagia as the presenting symptom of tetanus

Tetanus is an infectious disease affecting the neuromuscular system. Two of its most common symptoms, trismus and dysphagia, fall within the expertise of the otolaryngologist, and may result in the patient with the disease seeking his attention initially. Since the diagnosis of tetanus is a purely clinical one and does not involve diagnostic laboratory tests, it is of paramount importance for the practicing otolaryngologist to be thoroughly familiar with the clinical presentation of the disease.

Antibodies to peptides corresponding to a conserved sequence of gonococcal pilins block bacterial adhesion

Antisera generated against each of seven synthetic peptides corresponding to constant and variable sequences of the pilin from gonococcal strain MS11 were assayed for their ability to crossreact with intact pili from both homologous and heterologous strains. The peptides elicited roughly equal antipeptide responses but varied substantially in their ability to elicit antisera that crossreacted with intact pili. Of the antisera to peptides corresponding to regions of conserved sequence, antisera directed against residues 69-84 were the most efficient in binding pili from all strains tested in both solid-phase assays and immunoblots. Anti-69-84 also efficiently precipitated a tryptic fragment of pilin known to bind human endocervical cells. Sera against the two peptides (121-134 and 135-151) previously shown to contain strain-specific epitopes crossreacted with MS11 pili equally well, but differed in their ability to bind pili from heterologous strains. Anti-121-134 was strain-specific whereas anti-135-151 bound all pilin tested. Each of the sera was examined for its ability to inhibit bacterial adhesion to a human endometrial carcinoma cell line. Sera generated against residues 41-50 and 69-84 successfully inhibited a heterologous gonococcal strain from binding. These peptides could be important components of an effective vaccine for the prevention of gonorrhea.