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Biomedical subjects

M C Hawkins

Publications and source records attributed to M C Hawkins.

8 recordsLinked to original sources
PubMed1989

New high-flow "cloud" catheter for safer delivery of contrast material.

The authors describe a new angiographic catheter, which delivers equal flow rates through the side holes and reduced flow through the end hole compared with conventional catheters. Computer analysis of catheter-flow models revealed that placement of larger side holes proximally and smaller side holes distally produces more uniform flow rates out of the holes. This decreases the risk of potentially hazardous delivery of high-pressure jets of contrast material from the end hole. The flow pattern is so uniform that it resembles a cloud of contrast material on injection. This catheter design is particularly applicable for 3-5-F catheters, which require high-pressure injections. Clinical testing in 50 cases revealed no extravasations or unintentional selective injections with use of this catheter.

Angiography↗
PubMed1988

Retractable-barb needle for breast lesion localization: use in 60 cases.

A needle system with a retractable barb was developed for localization of nonpalpable breast lesions. The system can be repositioned without major adjustments and strongly anchors to breast tissue, eliminating failure due to dislodgment or transection of the localizing wire. Its use may necessitate fewer confirmatory radiographs, resulting in decreased radiation exposure. In addition, the needle can be retracted during surgery, to ease extraction of the specimen.

Biopsy, Needle↗
PubMed1984

A new deflector handle for catheter exchange.

The standard deflecting handle and deflecting wire have been modified to permit deflectors to be used as exchange wires. The spherical knobs are removed from the proximal end of the deflecting wire, and simple inserts are attached to the deflector handle. The handle can be used with deflector wires that have various length extensions (J or straight floppy tips) and with guidewires of variable stiffness.

Angioplasty, Balloon↗
PubMed1984

New monofilament and soft-wire baskets for stone removal.

A new-design basket for stone removal uses a standard Teflon catheter with radially positioned holes at its tip to hold either monofilament or soft wire. The strands are positioned to form a basket that will change in both size and shape simply by advancing or retracting these strands. This basket is much safer, can be changed in size during maneuvering , will transmit instruments for stone fragmentation, and can be advanced over a guide wire. It has been effective both in vitro and in the retrieval of biliary and urinary tract stones in 20 patients, several of which could not be retrieved by standard methods.

Animals↗
PubMed1984

Single-step placement of a self-retaining "accordion" catheter.

The "accordion" catheter was developed as an adjunct to the Hawkins needle guide to provide safe single-step percutaneous drainage. The Hawkins needle guide is a long, 22-gauge "skinny" needle-cannula system that can be used like any other skinny needle. It can also be used for drainage catheter placement. The accordion catheter is a 6.5 French Teflon catheter with a sigmoid tip. With the use of monofilament, the sigmoid tip can be retracted into a "T" configuration to prevent dislodgment. The 22-gauge needle guide, preloaded with an accordion catheter, can be manipulated safely while the drainage target is located. Then the accordion catheter can be advanced into the target over the needle guide. The "accordion" is easily formed, even in small targets. Successful drainage was achieved in 127 of 131 drainage procedures in which this technique was used. Sepsis did not occur as a complication in any of these procedures.

Abscess↗
PubMed1983

New coaxial exchange guide wire with a variable-length tip.

A new coaxial exchange guide wire, which has a variable-length, flexible "J"-shaped tip for exchanging drainage catheters in both large and small structures, is described. The design provides a gradual transition from the softness of the tip to the stiffness of the cannula. The system is presently available in two sizes (0.89 mm [0.035 in.] and 0.64 mm [0.025 in.]) and can also be used as a catheter end-hole dilator.

Biliary Tract↗
PubMedDate not supplied

Perinatal upregulation of benzodiazepine receptor ontogenesis: "fearless" and more efficient goal-directed behavior of adult rat progenies.

Pregnant and subsequently lactating rats had ad lib access to drinking water which contained either a benzodiazepine antagonist, Ro 15-1788 or diazepam (DZ). On the average, the rats consumed 2.9 mg/kg/day of Ro 15-1788 or 5.3 mg/kg/day of diazepam over the time period of 3 weeks, from gestation day 14 through postpartum day 14. The control group consumed equivalent volumes of the drug vehicle in water. While Ro 15-1788 had no apparent toxic effects, the numbers of viable pups in the DZ group were significantly reduced. The mean weight of the viable pups, and their gross behavior were not different in all three groups. However, the fully mature 4.5-month-old male progenies exposed to Ro 15-1788 were much more efficient in the radial arm maze test than the control or the diazepam-exposed animals; they rapidly habituated to the novel environment, their exploratory activity was uninhibited by distracting visual and auditory stimuli, they made fewer "working memory" errors in collecting baits, had a much better control over their emotional responses and the autonomic nervous system, as shown by very low defecation/urination scores, and, at the age of 5 months, they had a significant (66%) increase in the density of benzodiazepine receptors in the hippocampal formation, as compared to the control or the diazepam-exposed progenies. In conclusion, the upregulation of benzodiazepine receptor ontogenesis is retained in adult animals and resulted in improved "working memory" and better control over emotional responses that were particularly evident when the animals were challenged by novel and "intimidating" environmental stimuli.

Animals↗