Search PubMed⌕ Search

Biomedical subjects

J Hoffman

Publications and source records attributed to J Hoffman.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

Effectiveness of HIV risk reduction initiatives among out-of-treatment non-injection drug users.

While attention has been paid recently to the effectiveness of HIV/AIDS interventions among injection drug users, less focus has been given to out-of-treatment noninjecting drug users. This study examines the the NIDA Cooperative Agreement standard intervention versus an enhanced intervention for HIV/AIDS risk among noninjecting drug users. Data come from five sites of the NIDA-funded Cooperative Agreement on HIV risk behaviors. The sample is comprised of those who never injected drugs or reported not injecting in the 12 months prior to the interview; and who completed a three-month follow-up assessment. Three risk behaviors in the prior 30 days were analyzed: frequency of crack/cocaine use, number of sex partners, and frequency of condom use. The levels of both baseline and follow-up risk were analyzed. Individuals remaining at low risk or decreasing risk behaviors were classified as "improved." Those increasing risk behavior or remaining at moderate or high levels were classified as "worsened." Of the 1,434 noninjecting crack/cocaine users, 82% improved crack/cocaine use at the follow-up. The enhanced intervention group showed more improvement in crack/cocaine use than the standard intervention group. Overall, 76% reported reducing sexual partners, maintaining a one-partner relationship, or abstaining from sex at both time periods. Women in the enhanced intervention group improved more than women in the standard intervention (81% versus 75%). In terms of condom use, more respondents worsened than improved (55% versus 45%). This study confirms that HIV/AIDS interventions can reduce crack/cocaine use; however, high-risk sexual behaviors are more difficult to change. Reasons for this lack of improvement and suggestions for future interventions are discussed.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

HIV prevention protocols: adaptation to evolving trends in drug use.

Applied research in HIV prevention with out-of-treatment substance abusers takes place in a constantly changing environment. Researchers must be able to identify changes in drug use and sexual risk patterns, develop and evaluate appropriate interventions to respond to those changes, and find ways to make effective use of new technologies as they are developed. An example of this process is the collaborative revision made to NIDA's Standard Intervention for HIV prevention by the final six study sites funded under the NIDA Cooperative Agreements for AIDS Community-Based Outreach and Intervention Research. To illustrate the process of responding to changes in the substance abuse environment, to advances in knowledge about risk, and to newer technologies, this article provides an overview of the history of two federally funded HIV-prevention programs for out-of-treatment substance abusers and reviews recent changes made to the Standard Intervention protocol. The rationale for the changes is discussed, and the substance abuse population in the study is described.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Glyconeogenesis and urea synthesis in the toad Bufo viridis during acclimation to water restriction.

Metabolic consequences of osmotic stress were investigated in the toad Bufo viridis. Toads were acclimated either to terrestrial conditions in the absence of free water or to being partially immersed in 250 mmol L-1 NaCl, which was achieved by gradually increasing the salinity of the bath. This slow acclimation evoked little metabolic response, whereas the immediate osmotic challenge of water restriction resulted in a significant increase in the concentration of urea in the plasma and in liver glycogen. Urea accumulation, involving a transient increase in its rate of synthesis, allows the toads to lower their body water potential and thereby to absorb soil-bound water. The metabolic cost of this response is reduced by conserving the resulting by-product, glucose, as glycogen stored in the liver for future use.

Acclimatization↗
PubMedDate not supplied

Fertility drug therapies: past, present, and future.

Throughout the last 30 years there has been an evolution of drug therapies aimed at the treatment of infertility. These agents primarily address the induction of ovulation or enhancing ovulation by allowing more oocytes to mature simultaneously. As this evolution has progressed, drugs have moved away from human products to the advent of the recombinant or genetically engineered technology. The drugs have not cured infertility, but they have affected positively the quest of families confronted by infertility.

Adult↗
PubMedDate not supplied

Development of a computerized screening system to identify substance abuse in primary care.

The Drug and Alcohol Problem Assessment for Primary Care (DAPA-PC), developed under a contract from the National Institute on Drug Abuse, is a comprehensive screening system developed for quickly identifying and addressing substance abuse and related problems in a primary care setting. The DAPA-PC system includes a two-level screening instrument, resources for scoring and reporting results, motivational messages, treatment referrals, and informative links, which together address the multifaceted needs of patients dealing with addiction problems and their providers. The need for such a system, preliminary reactions to the instrument, and future course of research are discussed.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Pancreatic tumour marker anti-mucin antibody CAM 17.1 reacts with a sialyl blood group antigen, probably I, which is expressed throughout the human gastrointestinal tract.

CAM 17.1 is an antimucin monoclonal antibody which has recently been proven valuable as a reagent for serological diagnosis of pancreatic cancer. A series of studies have been performed to characterise its epitope. First it was screened immunohistochemically against a wide range of formalin-fixed normal and neoplastic human tissues and showed widespread binding to mucin throughout the gastro-intestinal tract, in both normal and malignant tissues. In pancreas, strong intracellular staining of acinar and ductal cells was found in normal tissue and in carcinoma cells in tumours. Normal stomach showed only weak staining (n = 6), but gastritis with metaplasia showed strong staining (n = 4). Staining of colonic mucosa from patients of known Lewis phenotype showed Le(a+b-) (7/8) and Le(a-b+) (4/6) samples to be positive, but not Le(a-b-) (0/3) samples. CAM 17. 1 agglutinated all donor erythrocytes tested at 4 degreesC regardless of blood group, whereas cord blood red cells were not agglutinated. Since I antigen is the only antigen known to be present on all adult red blood cells but absent from cord blood, this suggests probable involvement of this antigen in the binding site. The agglutination was abolished by sialidase treatment of the red cells and immunoblotting with slot-blotted mucin showed that binding was both acid and sialidase sensitive indicating the involvement of sialic acid in the binding site. These studies show that CAM 17.1 binds to a sialic-acid-containing determinant of mucin, probably sialyl-I, which epitope shows wide distribution throughout the gastro-intestinal tract.

Adult↗
PubMedDate not supplied

Software for real-time control of a tidal liquid ventilator.

The purpose of this project was to develop and test computer software and control algorithms designed to operate a tidal liquid ventilator. The tests were executed on a 90-MHz Pentium PC with 16 MB RAM and a prototype liquid ventilator. The software was designed using Microsoft Visual C++ (Ver. 5.0) and the Microsoft Foundation Classes. It uses a graphic user interface, is multithreaded, runs in real time, and has a built-in simulator that facilitates user education in liquid-ventilation principles. The operator can use the software to specify ventilation parameters such as the frequency of ventilation, the tidal volume, and the inspiratory-expiratory time ratio. Commands are implemented via control of the pump speed and by setting the position of two two-way solenoid-controlled valves. Data for use in monitoring and control are gathered by analog-to-digital conversion. Control strategies are implemented to maintain lung volumes and airway pressures within desired ranges, according to limits set by the operator. Also, the software allows the operator to define the shape of the flow pulse during inspiration and expiration, and to optimize perfluorochemical liquid transfer while minimizing airway pressures and maintaining the desired tidal volume. The operator can stop flow during inspiration and expiration to measure alveolar pressures. At the end of expiration, the software stores all user commands and 30 ventilation parameters into an Excel spreadsheet for later review and analysis. Use of these software and control algorithms affords user-friendly operation of a tidal liquid ventilator while providing precise control of ventilation parameters.

Algorithms↗
PubMedDate not supplied

Recent innovations in total liquid ventilation system and component design.

In addition to partial liquid ventilation (PLV), total liquid ventilation (TLV) is being explored as a potential therapy to mitigate ventilator-associated lung injury and acute lung failure. TLV is ventilation of the completely liquid-filled lung using tidal flow of oxygenated perfluorochemical (PFC) liquid delivered by a "liquid ventilator." Most TLV research to date has focused on "small" lung (animals < 20 kg; vast majority < 5 kg), with primary relevance to its use in children. Recent investigations regarding TLV in larger lungs have helped define new design challenges for liquid ventilator systems to succeed as clinical products. Adult TLV requires the delivery of significantly higher liquid tidal volumes, with proportionately greater O2 and CO2 exchange. Although a simple scale-up of liquid ventilator components such as pumps, tubing, fittings, and gas and heat exchangers might be considered the most straightforward way to compensate for the increased demand, there are a number of practical problems with this approach. These include requirements to: 1) minimize priming volume, 2) minimize PFC evaporative loss, 3) suppress flow-induced cavitation in fittings and components, 4) monitor and control ventilation based on pressure signals exhibiting noise, 5) maintain ability and accuracy of delivered breaths in a fluid mechanical environment having higher inertial forces and pressure losses than for small lung systems, 6) use disposable or sterilizable fluid-contacting components, and 7) maintain PFC materials compatibility. TLV system and component innovations implemented on a new large-animal liquid ventilator prototype are presented. The advantages of new pumps, gas exchangers, and temperature-control components are discussed.

Adult↗
PubMedDate not supplied

Dose monitoring in Partial Liquid Ventilation by infrared measurement of expired perfluorochemicals.

Patients undergoing Partial Liquid Ventilation (PLV) with the perfluorochemical liquid perflubron (PFB) continuously evaporate the drug from the lung during ventilatory expiration. In this study, two infrared (IR) devices, a modified industrial analyzer ("experimental prototype") and a custom-designed device suitable for use in a clinical environment ("clinical prototype"), were calibrated and validated on the bench to measure a range of PFB concentrations (CPFB) in a gas stream. PFB loss from the lung (area under the CPFB-vs-time-curve) could be correlated during PLV simulation with changes in tidal volume, breathing rate, and variable CPFB-vs-time profiles. The two IR devices produced nearly identical measurements for the same CPFB standards (maximum deviation = 1.5%). The experimental IR prototype was tested in 17 anesthetized, paralyzed, and ventilated swine (42-53 kg) to quantify the total amount and rate of evaporate loss of PFB over 12 hours of PLV, both with and without periodic supplemental PFB doses. The residual PFB volumes in the animal lungs at the end of the study, as determined by a gravimetric postmortem lung method, were found to agree on average for all animals to within 10% of the residual PFB volume as predicted by the IR approach. Furthermore, the IR signal of CPFB does not appear to correlate with the absolute amount of PFB in the lungs, but may reflect the relative proportion of PFB-wetted airway and alveolar surface. The authors conclude that IR quantitation of PFB evaporative loss is acceptably accurate for extended periods of PLV and may be a useful tool in the clinic for PFB dose monitoring and maintenance, thereby helping to optimize PLV treatment.

Algorithms↗
PubMedDate not supplied

A closed rebreathing system for dose maintenance during Partial Liquid Ventilation.

Partial Liquid Ventilation (PLV), a treatment for acute respiratory failure in which the lungs are filled, either partially or to functional residual capacity (FRC), with perfluorochemical (PFC) liquid while the patient is on mechanical gas ventilation, has progressed to clinical trials using the PFC perflubron (PFB). Because gas expired during PLV is laden with PFB vapor, PFB is lost via evaporation, which increases dose consumption and necessitates periodic redosing. A device has been developed to minimize evaporative loss by confining PFC vapor to a gas volume breathed by the patient, which is isolated from the ventilator. This closed rebreathing system works with the ventilator such that after the lung is filled with PFB, the patient is connected to the rebreathing system, with breathing still "driven" by the ventilator. The rebreathing system consists of two gas circuits, or compartments, separated by a flexible bag (in a box) partition. One compartment is in gas communication with the lung, while the second communicates with the ventilator. The O2 level on the patient side is matched to that on the ventilator side by sensing gas concentrations and by feedback control of O2 introduction. Similarly, air is introduced into the patient side under pressure-based feedback control to maintain a constant gas volume. On inspiration, the ventilator delivers the tidal volume (breath) into the box surrounding the bag, which, in turn, is transmitted through the bag to the lung. On expiration, the process is reversed. Unidirectional circulation of gas in the rebreathing circuit is achieved via check valves, and expired CO2 is removed by a barium hydroxide lime cartridge. Airway humidification is maintained by captive water vapor in the system and water vapor from the CO2 absorber. It is recommended that flow, pressure, O2, and CO2 levels be monitored at the patient "Y," i.e., the proximal end of the endotracheal tube. Performance data from both in-vitro experiments and in-vivo PLV experiments in pigs are presented. The authors conclude that with the closed rebreathing system, the dose can be safely maintained with fewer redosing procedures, and an approximately 90% savings in dose is achieved.

Animals↗
PubMedDate not supplied

Lidocaine hydrocarbonate is not superior to lidocaine hydrochloride in interscalene brachial plexus block.

To determine the effect of carbonation of lidocaine, a comparison of 1.0% lidocaine hydrochloride (HCl) and 1.1% lidocaine hydrocarbonate (CO2), both with 1:200,000 epinephrine, was made in this study of 50 patients receiving interscalene brachial plexus blocks. Sensory block was determined by the response to pinprick in the C2-T2 dermatomes, while motor block was assessed by the development of paresis and paralysis at the shoulder and hand. The percentage of patients developing analgesia (decreased sensation to pinprick) and anesthesia (total absence of sensation to pinprick) at each dermatome level as well as the percentage of patients developing motor block was not significantly different between the two forms of lidocaine. The initial onset of analgesia [lidocaine HCl, 4.0 +/- 2.4 (SD) minutes; lidocaine CO2, 4.3 +/- 3.8 (SD) minutes] and anesthesia [lidocaine HCl, 10.1 +/- 5.7 (SD) minutes; lidocaine CO2, 7.8 +/- 4.4 (SD) minutes] did not differ significantly between the two groups. At the individual dermatomes, there was no difference in the onset of analgesia except at one dermatome level, C7, which was near the level of local anesthetic injection. Anesthesia onset in each dermatome as well as the onset of motor block did not differ between the two groups. It is concluded that lidocaine CO2 does not offer any significant clinical advantage over lidocaine HCl in interscalene brachial plexus block.

Adult↗
PubMedDate not supplied

Transarterial techniques are not effective for subclavian perivascular block.

Although transarterial techniques have been commonly used for axillary block, results with these techniques have not been previously described for subclavian perivascular block. We studied the efficacy and complications of two types of arterial techniques for subclavian perivascular block. In Group 1 (n = 10), the subclavian perivascular injection was made after withdrawing the needle from the subclavian artery (top of artery), and in Group 2 (n = 8), the injection was made after advancing through the subclavian artery (bottom of artery). The local anesthetic used was lidocaine 1.5% with epinephrine 1:200,000 in a volume determined by the formula [ml = (height in inches divided by 2) + 5]. Both techniques were associated with a low incidence (50% or less) of anesthesia throughout the brachial plexus dermatomes. Sixty percent of patients in Group 1 and 63% of patients in Group 2 required supplemental blocks. In view of the low incidence of anesthesia and the frequent need for supplementation, additional patients were not enrolled in the study. Complications associated with the technique included hematoma (12-20%), recurrent laryngeal nerve block (10-25%), Horner's syndrome (0-20%) and phrenic nerve block (75-80%). Despite the relatively high dose of lidocaine used, serum lidocaine levels remained well below the toxic range.

Aged↗