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Biomedical subjects

S L Michel

Publications and source records attributed to S L Michel.

At least 19 recordsLinked to original sources
PubMed2001

Solitaire and gemini metallocene porphyrazines.

We report the synthesis and physical characterization of a series of peripherally functionalized porphyrazines (pzs) of the forms H2[pz(A;B3)] and trans-H2[pz(A2);B2], where A is a dithiolene chelate of molybdocene or vanadocene and B is a solublizing group. The precursor pz's 8 and 9, of the form H2[pz(A;B3)], where A = (4-(butyloxycarbonyl)-S-benzyl)2 and B = di-tert-butylphenyl (8) or di-n-propyl (9), have been prepared, deprotected, and peripherally metalated with molybdocene and vanadocene to form 1(Mo(IV)) and 1(V(IV)), prepared from 8, and 2(Mo(IV)) from 9, respectively. Likewise, the protected trans-H2[pz(A2);B2)], where A = (S-benzyl)2 and B = 3,6-butyloxybenzene (12) or A = (S-benzyl)2 and B = (tert-butylphenyl)2 (13), have been prepared and peripherally metalated with molybdocene and vanadocene to give the trans dinuclear complexes, 3(Mo(IV),Mo(IV)), 3(V(IV),V(IV)) (from 12), and 4(V(IV),V(IV)) (from 13). A crystal structure of the trans vanadocene pz 4(V(IV),V(IV)) is presented; the distance between the two vanadium atoms is 14.5 A. The molybdocene-appended pz's are highly redox active and exhibit cyclic voltammograms that are more than just the sum of the metallocene and the parent pz's. Chemical oxidation with FcPF6 gives the Mo(V) species 1(Mo(V)), 2(Mo(V)), 3(Mo(V),Mo(IV)), and 3(Mo(V),Mo(V)). Their EPR spectra are indicative of extensive delocalization from the Mo(V) into the dithiolato-pz. The EPR spectrum of the mononuclear paramagnetic vanadocene pz, 1(V(IV)), shows an expected 8-line pattern for an S = 2 system with hyperfine coupling to a single 51V (I = 7/2) nucleus, but the dinuclear vanadocene pz's, 3(V(IV),V(IV)) and 4(V(IV),V(IV)), exhibit a striking 15-line pattern of the same breadth from the S = 1 state formed by exchange coupling between the S = 2 vanadium centers of a dinuclear complex. Thus, the porphyrazine macrocycle is capable of mediating magnetic exchange interactions between metal ions bound to the periphery, separated by 14.5 A.

Journal Article↗
PubMed2001

Optical, magnetic, and electronic properties of peripherally fused macrocycles: molybdocene porphyrazines.

Metal-free and copper porphyrazines, [H(2)pz] and [Cu pz], have been fused at the periphery with molybdocene dithiolene, [Cp(2)Mo]. The optical, magnetic, and electronic properties of the resulting neutral and cationic complexes are studied, using first-principles density functional theory implemented by the discrete variational method. Analysis of the charge and spin distribution shows that the porphyrazine core is strongly coupled with the peripheral complex. The calculated optical absorption is found to be in reasonable agreement with experimental spectra, lending support to our theoretical model. Under appropriate circumstances one observes interaction of unpaired spins localized in the vicinity of both metal sites. The calculated spin distribution shows that [Cp(2)Mo][Cu pz] and [Cp(2)Mo][H(2)pz](+) have a magnetic moment of 1 micro(B) while [Cp(2)Mo][Cu pz](+) and [Cp(2)Mo][H(2)pz] have no moment, in good agreement with the results of X-band EPR spectra. The Cu-Mo magnetic interaction is antiferromagnetic, being mediated by pyrrol nitrogens, meso nitrogens, carbons, and sulfurs.

Journal Article↗
PubMed1985

Relation of free silicone to human breast carcinoma.

Of 12 women with carcinoma of the breast and coexistent silicone mastopathy, nine had had injections of liquid silicone for breast augmentation; three had leaking silicone-gel prostheses. The clinical findings indicated that early diagnosis was obscured by the silicone-induced mastopathy, which rendered the interpretation of physical findings and mammograms difficult. The pathologic findings were suggestive of a possible adverse effect of the presence of free silicone within the breast tissue, axillary nodes, and axillary fat. Although no causal relationship between silicone and breast carcinoma is implied, a heightened awareness of the possible coexistence of silicone mastopathy and breast carcinoma is necessary.

Adult↗
PubMed1984

Hamartomas of the spleen.

A study of 12 cases of splenic hamartomas, rare benign lesions of the spleen, included one case of spontaneous rupture of a hamartoma that required emergency operation and two cases of hamartomatosis with splenomegaly. An increased incidence of accessory spleens was also noted. Therefore, although rarely symptomatic, hamartomas may occasionally be of clinical importance. Surgeons should be aware of these lesions in the differential diagnosis of splenic tumors that appear as filling defects on scintiscan or as splenic masses on abdominal exploration. Since it may also be a source of spontaneous splenic rupture, it should be considered as one of the rare causes of such an occurrence.

Adult↗
PubMed1984

Surgical procedures in nonagenarians.

During the hospital course of 225 nonagenarian patients who underwent 285 major operations-80% on the general, vascular, orthopedic and urologic services-overall morbidity was 37% and mortality 7.5%. The 100 emergency operations were associated with a higher morbidity and mortality rate. Nonsurvivors were more likely to have associated cardiac or cerebral medical conditions, higher utilization of intraoperative invasive hemodynamic monitoring and greater use of surgical intensive care units. Compared with all surgical patients, the nonagenarians were admitted twice as often to the surgical intensive care unit, required twice the number of hospital days, underwent intraoperative hemodynamic monitoring twice as frequently and incurred 200% greater hospital charges. We conclude that with careful evaluation and management, a nonagenarian patient presenting with a surgical condition can safely undergo necessary operative procedures.

Aged↗
PubMed1983

Melanosis coli. Changes in appearance when associated with colonic neoplasia.

In 30 cases of colonic neoplasia associated with melanosis coli, proliferating or neoplastic colonic epithelium was notable within the melanotic colons by virtue of a striking absence of pigmentation. Microscopically this characteristic was found to be due to an absence or diminution of pigment-laden macrophages in the lamina propria underlying such lesions. Therefore, the absence of pigment-laden macrophages can be considered a marker for abnormally proliferating epithelium. This characteristic may denote a cellular or humoral change mediated by macrophages in association with neoplastic epithelium.

Colonic Diseases↗
PubMed1983

The left transverse colostomy.

The right transverse colostomy is the one traditionally performed for distal colonic obstructive tumors, perforated sigmoid diverticulitis, distal colonic injuries, or for the protection of precarious low colonic anastomoses. However, the right transverse colostomy has a tendency to prolapse; its effluent is frequently liquid; it cannot be performed without producing adhesions in the right upper quadrant; and it obligates the surgeon generally to three operations when done as the first part of a staged colonic resection. The left transverse colostomy has the advantages of a reduced incidence of prolapse, an increased length of absorptive surface, absence of adhesions in the right upper quadrant, and the possibility of a two-stage resection. Fifteen instances in which left transverse colostomies were performed with diverse indications formed the basis for this report.

Colonic Diseases↗
PubMed1983

Emergency minilaparoscopy in abdominal trauma. An update.

In 106 cases of blunt abdominal trauma, the emergency minilaparoscope was used as a diagnostic tool. In 57 patients (53.5 percent), the findings proved to be negative. In 22 patients (20.8 percent), the laparoscopic findings were corroborated by exploration. But, in 27 instances (25.4 percent), minimal to moderate hemoperitoneum was found and the laparoscopic view indicated that these patients could be treated nonoperatively with close observation. None of these patients required subsequent exploration. There were no complications of laparoscopy which required surgical intervention. In our opinion, minilaparoscopy is more diagnostically accurate than lavage. It is a fast and safe examination which can be performed at the bedside with the patient under local anesthesia. The number of unnecessary abdominal explorations in severely injured patients can be reduced to a negligible figure, thus decreasing morbidity, hospitalization time, and costs.

Abdominal Injuries↗
PubMed1979

'Malignant' diverticulitis: a clinical entity.

A form of severe diverticulitis exists that is characterized by (1) phlegmonous inflammation of the sigmoid and rectosigmoid colon, often extending below the peritoneal reflection, (2) frequent fistulization to skin, urinary bladder, and small intestine, (3) frequent colonic obstruction, and (4) high postoperative morbidity and mortality. The clinical similarity to granulomatous colitis is very apparent, but pathologic findings are consistent with severe diverticulitis rather than granulomatous colitis. The term "malignant" diverticulitis is suggested because of the progressive nature of the disease process and the frequency of severe morbidity associated with it. Seventeen patients have been studied since 1965, comprising approximately 7% of patients operated on for diverticular disease at Cedars-Sinai Medical Center.

Aged↗
PubMed1977

Control of hepatic bleeding with microfibrillar collagen.

Microfibrillar (Avitene) is a new absorbable topical hemostatic agent whose mechanism of action is platelet entrapment and activation of platelet clotting factors. It adheres to moist tissue surfaces to form a firm, flexible hemostatic coagulum. It has been used clinically in 36 patients with hepatic bleeding of diverse etiology, including bleeding from the gallbladder fossa, lacerations, resectional surfaces, biopsy sites, capsular denudations, and hepatic tumors. Although not intended to control major hemorrhage were major vessel ligation or resection is properly indicated, its topical use for diffuse small vessel bleeding may be life-saving. It is exceptionally useful in such conditions as cirrhosis and in thrombocytopenic or thrombasthenic coagulopathies. One treatment failure out of 36 occurred.

Aged↗
PubMed1977

'Routine' liver biopsy in upper abdominal surgery.

Liver biopsy was done at the time of operation in 125 consecutive upper abdominal procedures to assess the incidence of unsuspected or undiagnosed hepatic abnormalities. Specifically excluded were hepatic lesions unexpectedly identified at laparotomy. Sixty-seven percent of the liver biopsy specimens were abnormal, the most frequent findings being fatty metamorphosis, cholestasis, triaditis, fibrosis, inflammatory infiltrate, cholangitis, cirrhosis, and hepatitis. The most frequent operation performed was cholecystectomy. In 63 patients with chronic cholecystitis, there was a 51% incidence of abnormal liver histology, while in nine patients with acute cholecystitis, the incidence was 78%. In 83% of all other operations, abnormal liver biopsy specimens were identified. Bile leakage, hemorrhage, and infection did not occur in this series, despite inclusion of patients with severe biliary obstruction, abnormal clotting factors, and intra-abdominal sepsis. New techniques of histochemical enzyme analysis and electron microscopy are expected to enhance the clinical correlation of occult hepatic lesions. We conclude that liver biopsy in a safe, informative adjunct to all upper abdominal procedures.

Abdomen↗
PubMed1976

Fruit pit obstruction. "The propitious pit.".

Ingestion of fruit pit must be a frequent and innocuous phenomenon, judging from the expected frequency of such occurrences and the relative dearth of medical reports to the contrary. Reported here are four cases in which fruit pits of varied nature completed an otherwise incomplete intestinal obstruction. On of these was in the terminal ileum, with incomplete obstruction due to regional ileitis, in which the offending pit was seen radiologically but was not recognized as such. The other three were in the transverse colon, at the site of annular carcinomatous lesions. The completion of the obstruction by the fruit pits eventuated in earlier symptoms, diagnosis, and treatment. In one case, the fruit pits were multiple; in the remainder, they were single.

Aged↗