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Biomedical subjects

D R Cahill

Publications and source records attributed to D R Cahill.

At least 37 records · Page 2Linked to original sources
PubMed1993

Supraclavicular nerve block: anatomic analysis of a method to prevent pneumothorax.

Supraclavicular nerve blocks are technically easy to perform, but may be associated with pneumothorax. The objective of this study is to define the parasagittal anatomy important to our modified technique of supraclavicular nerve block designed to decrease the incidence of pneumothorax and to determine whether this technique is anatomically sound. Two cadaver specimens were studied. One embalmed specimen was dissected to establish the relationship of the brachial plexus to our modified needle entry site. The neck and upper thorax of an unembalmed cadaver were frozen, and parasagittal serial sections were made to establish the relationship of the brachial plexus to surface features and the chest cavity. Additionally, 12 volunteers underwent magnetic resonance (MR) imaging and anatomic measurements of their supraclavicular anatomy important to our modified block. MR imaging showed that in no instance using our modified technique was the lung contacted by the simulated needle before entering either the subclavian artery or contacting the brachial plexus. Our technique has been used in more than 110 patients without pneumothorax. The combination of our cadaver and magnetic resonance data suggests that our plumb-bob technique of supraclavicular nerve block is anatomically sound and may minimize the development of pneumothorax during supraclavicular block.

Brachial Plexus↗
PubMed1989

Sectional anatomy of the larynx: implications for the transcutaneous approach to endolaryngeal structures.

A transcutaneous, transcricothyroid membrane approach to endolaryngeal structures is used for several techniques such as placement of electrodes for laryngeal electromyography and transcutaneous Teflon injection of the paralyzed vocal fold. The purpose of this study is to examine the sectional anatomy of the larynx with respect to the cricothyroid membrane and describe a suitable transcutaneous approach to endolaryngeal structures. Sixteen whole organ cadaveric larynges were frozen in clear gelatin to facilitate sectioning. Specimens were sectioned in the transaxial, sagittal, and coronal planes as well as 30 degrees, 45 degrees, and 60 degrees from the transaxial plane. For clinical orientation, the transaxial plane was defined as 90 degrees from the most anterior plane of the cricothyroid membrane. Sections were examined and angles and depths of penetration were measured with respect to the transcutaneous approach to endolaryngeal structures.

Female↗
PubMed1988

Magnetic resonance imaging of the wrist: normal cross sectional imaging and selected abnormal cases.

Using a small surface coil and limited field of view, the authors have generated 13 contiguous, 3 mm, transverse sections of the wrist of a cadaver. The identity of the structures recorded has been established by subsequent dissection of the cadaver. The article presents the 13 MR sections together with drawings identifying the recorded structures at each level. These anatomic sections are amplified by 7 transverse MR images showing alterations of the normal anatomy in clinical examples of wrist pathology.

Giant Cell Tumors↗
PubMed1988

Developmental changes in the extracellular matrix of the dental follicle during tooth eruption.

Eruption of the third and fourth mandibular premolars in the dog begins at 15 weeks of age, is dependent upon the dental follicle, and is complete by 23 weeks. Our study covered the period from 12 to 20 weeks, and revealed several changes in extracellular matrix structure and organization of the follicle which correlate with specific physiological events in eruption. First, the average DNA content per follicle reached a maximum at 14 weeks. Two weeks later, follicle size had increased 1.3- to 2.4- times. Second, the collagen content of follicles increased 2.5-fold over the study period, with two-thirds of this increase over the last four weeks. Type I collagen was the major collagen at all stages of follicular development. The amount of proteoglycan rose 45% from 16 to 20 weeks of age. Third, the ultrastructure of the dental follicle prior to eruption (12 weeks) indicated a disorganized interstitial connective tissue matrix; during eruption, two size classes of fibrils were observed which clustered together in linearly aligned bundles. Fourth, gel electrophoretic analyses resolved more than twenty follicle proteins with the major species a Mr = 95k glycoprotein. Immunoblotting demonstrated only one minor component was derived from serum. Comparison of noncollagenous proteins from different aged follicles indicated that three small polypeptides (Mr = 20-25 k) were present primarily at 16 weeks, the same time at which root elongation begins. A different sequence of changes was exhibited by two other proteins of Mr = 13 and 15 k. These findings may serve as biochemical markers of stages of dental follicle development and facilitate a search for local control mechanisms.

Aging↗
PubMed1988

Obturator hernia.

Obturator hernias are relatively rare. In the past 15 years at the Mayo Clinic, eight patients underwent nine operations for repair of 11 obturator hernias, which represented 0.073 per cent (11 of 15,098) of all hernias repaired at this institution. Elderly women with chronic disease were most frequently affected. Symptoms were usually intermittent; mechanical small intestinal obstruction was the most common presenting condition, followed by pain in the thigh or groin area. The Howship-Romberg sign was found in only two patients, and a correct preoperative diagnosis was made in only one patient. Midline abdominal incisions were made in all patients. Incarcerated ileum was the most frequently encountered organ in the hernia sac. Surprisingly, foci of endometriosis in the obturator defect accounted for symptoms in two patients with three obturator hernias. Right-sided obturator hernias outnumbered left, and bilateral obturator hernias were found synchronously in two instances and metachronously in one instance. The often debilitated state of the patients with obturator hernia and the frequent delay of diagnosis combined to produce significant operative morbidity and mortality rates.

Adult↗
PubMed1987

Prostate shape, external striated urethral sphincter and radical prostatectomy: the apical dissection.

In an anatomical study of 64 gross specimens the external striated urethral sphincter was reconfirmed to extend as a single unit from the proximal penile urethra to the bladder base. The configuration of the external striated urethral sphincter was variable and was related to the shape of the apical prostate. Two basic prostatic shapes were recognized, distinguished by the presence or absence of an anterior apical notch. Whether a notch existed depended upon the degree of lateral lobe development and the position of its anterior commissure. In radical prostatectomy knowledge of the variation in the shape of the prostatic apex can help the surgeon to achieve optimal urethral transection with maximal preservation of the external striated urethral sphincter and other tissues of the continence mechanism.

Aged↗
PubMed1987

Anatomy of the sural nerve complex.

The anatomy of the sural nerve complex in 20 cadaveric limbs was determined by dissection. The nerve usually consists of four named components: the medial sural cutaneous nerve, the lateral sural cutaneous nerve, the peroneal communicating branch, and the sural nerve. In most instances (80%), the sural nerve is formed in the distal portion of the leg by the union of the medial sural cutaneous nerve and the peroneal communicating branch. In 20% of cases, the peroneal communicating branch is absent. In such cases, the sural nerve is derived from the medial sural cutaneous nerve alone. The lateral sural cutaneous nerve is laterally situated and usually divides into medial and lateral branches. In a few cases, its medial division may contribute to the sural nerve through the peroneal communicating branch. The peroneal communicating branch can be of substantial caliber and may be useful as a source of nerve graft without complete sacrifice of the sural nerve. We describe a technique of isolation of the peroneal communicating branch for use as a nerve graft.

Humans↗
PubMed1987

Regional control by the dental follicle of alterations in alveolar bone metabolism during tooth eruption.

Tooth eruption is a localized, bilaterally symmetrical series of events which involves resorption and formation of alveolar bone on opposite sides of the tooth and requires the presence of the dental follicle. We examined the effect on eruption of selective surgical removal of parts of the follicle. Removal of either the basal or coronal halves of the follicle prevented eruption. Bone resorption and formation of an eruption pathway did not occur after removal of the coronal part of the follicle and bone formation did not occur after removal of the basal part of the follicle. Exposure and incisions of the follicle had no effect on eruption. We interpret these data to mean that the polarized resorption and formation of alveolar bone that occur around a tooth during eruption are regulated by the adjacent parts of the dental follicle.

Alveolar Process↗
PubMed1986

Ultrastructure of alveolar bone during tooth eruption in the dog.

Previous work from our laboratories has established that eruption of the permanent mandibular premolars in dogs is dependent upon the presence of the dental follicle and that it involves resorption of alveolar bone and the roots of the deciduous predecessor above and formation of alveolar bone below the developing crown. This study illustrates the topography of the bone surfaces of the crypt by scanning electron microscopy and the ultrastructure of the cells on alveolar bone surfaces during tooth eruption. Above the developing crown where the eruption pathway forms, the bone surface is a pitted sheet, the characteristic topographic feature of bone resorption; between the crown and the mandibular canal, the bone surface has numerous interconnecting trabeculae. Transmission electron microscopy of bone cells lining the eruption pathway area of the crypt showed numerous osteoclasts with adjacent mononuclear cells. Both cell types contained specific, membrane-bound cytoplasmic vesicles shown by the work of others to be characteristic features of osteoclasts and their precursors. Basal trabeculated bone in the crypt was covered by plump osteoblasts. These data show that the metabolic events in alveolar bone associated with tooth eruption have the appropriate cellular and bony surface correlates and that the suspected control of alveolar bone resorption by the dental follicle may be mediated by its recruiting and directing to adjacent bone surfaces the mononuclear precursors of osteoclasts.

Alveolar Process↗
PubMed1986

Cross-sectional anatomy of the pericardial sinuses, recesses, and adjacent structures.

Detailed drawings of four cross sections through the mediastinum which pass through the sinuses and recesses of the pericardial cavity, are presented. The drawings depict the location and extent of the pericardial sinuses, recesses, and their closely associated extrapericardial structures. Two previously unnamed recesses within the serous pericardium are defined and named, one the inferior aortic recess of the transverse sinus and the other, the right pulmonic recess of the transverse sinus. The terminology of the pericardial sinuses and recesses has been inconsistent, and the authors propose a nomenclature for standardizing the names of the recesses of the serous pericardium. Important anatomic pericardial relationships with regard to pericardial effusions and lymphadenopathy are discussed.

Diagnosis, Differential↗
PubMed1986

Lymphocytes capable of mediating delayed-type hypersensitivity reactions accumulate within sponge matrix allografts.

The rejection of sponge matrix allografts across H-2 barriers has generally been found to contain specifically sensitized cytotoxic T cells to donor alloantigen. There is one exception: sponge matrix allografts that differ only with respect to class II alloantigens do not contain specifically sensitized cytotoxic T cells. We therefore investigated the capacity of infiltrating cells removed from sponge matrix allografts to generate delayed hypersensitivity reactions after exposure to fresh alloantigen in a footpad assay. Cells infiltrating class I and II allografts were equally capable of eliciting delayed footpad reactions when injected with specific donor alloantigen into the footpads of naive responder strain mice. Allosensitized T-lymphocyte clones of helper or cytotoxic type were also capable of initiating delayed-type hypersensitivity (DTH) reactions in vivo. We conclude that rejecting allografts across class I or II alloantigenic barriers are infiltrated by cells capable of effecting DTH reactions, in addition to their capacity to exert specific helper or specific cytotoxic reactions. The results also support that both helper and cytotoxic T cells can participate in allospecific DTH reactions.

Animals↗
PubMed1985

Supplemental clinical dissections for freshman gross anatomy.

This paper describes a series of nine short clinically oriented dissection exercises as supplements for freshman gross anatomy courses. These procedures heighten and focus student interest, and they do not extensively lengthen the time required to accomplish the regular dissection assignments. The exercises are: lumbar puncture, anterior approach for shoulder arthroplasty, acromioclavicular dislocation, fenestration of the diaphragm, appendectomy, cholecystectomy, display of the facial nerve as in parotidectomy, posterior approach for hip arthroplasty, and injuries to the knee ligaments and meniscectomy.

Acromioclavicular Joint↗
PubMed1985

Ultrastructural features of the dental follicle associated with formation of the tooth eruption pathway in the dog.

The dental follicle is a loose connective tissue layer that surrounds the developing and erupting tooth. The follicle is necessary for tooth eruption in dogs and specific cellular changes occur in the follicle at the onset of tooth eruption. In particular, within the coronal region of the follicle next to areas of subsequent bone resorption there is an increase in mononuclear cells which have the ultrastructure features of monocytes and contain specific granules characteristic of preosteoclasts. The follicle has an extensive microvasculature and monocytes are often seen adjacent to capillaries and venules. Monocytes increase in number in direct proportion to the increase in osteoclasts that form the eruption pathway and decrease in number as soon as this activity is completed. It is postulated that monocytes enter the follicle from the microvasculature and then migrate to the walls of the bony crypt to participate in the formation of the eruption pathway.

Age Factors↗