Theoretical and experimental investigations of Coulomb blockade in coupled quantum dot systems.

Two strongly coupled quantum dots are theoretically and experimentally investigated. In conductance measurements on a GaAs based low-dimensional system additional features to the Coulomb blockade have been detected at low temperatures. These regions of finite conductivity are compared with theoretical investigations of a strongly coupled quantum dot system and good agreement between the theoretical and the experimental results has been found.

Aneurysms of the carotid arteries associated with von Recklinghausen's neurofibromatosis.

Aneurysms of both common carotid arteries were seen in a patient with neurofibromatosis. Histologic examination of the involved arteries demonstrated a dense proliferation of spindle cells within the arterial walls accompanied by medial cystic degeneration and disruption of the tunica elastica. These changes were also observed in adjacent, grossly uninvolved segments of the blood vessels. Immunohistochemical analysis of the proliferating cells was positive with antibodies against desmin and muscle-specific actin. The findings demonstrate and confirm the smooth muscle origin of the aberrant proliferated cell population in arteries in a patient with von Recklinghausen's neurofibromatosis.

[Diagnosis of Edwards syndrome in newborns]. / Diagnostyka zespolu Edwardsa u noworodków--obserwacje wlasne.

Congenital malformations most useful for the diagnosis of trisomy 18 in the first days of life were defined based on observations of newborns with Edwards syndrome treated at the Child Health Center in 1992-1994. Intrauterine growth retardation, facial skeleton dysmorphy, congenital heart malformation, mainly VSD, extremity malformations, especially of the palms and feet found in the newborn suggest a diagnosis of Edwards syndrome. The need to differentially diagnose trisomy 18 with autosomal recessive syndrome TAR, Roberts and Smith-Lemli-Opitz is stressed.

Expression of keratin 13 in human epithelial neoplasms.

The distribution of the 52 kDa keratin 13 was evaluated immunohistochemically, using the AE8 monoclonal antibody. Various squamous and transitional cell epithelial lesions and representative control tissues were studied. This antibody performed adequately in formalin-fixed and paraffin-embedded tissue, but like keratin immunohistochemistry in general, required protease pretreatment. Keratin 13 was found consistently in the suprabasal layers of squamous epithelia of oral cavity, tonsils, larynx, esophagus, lower female genital tract, and transitional urothelium, but it was absent in the epidermis. Generally, various forms of squamous metaplasia were AE8-positive. In dysplasia, AE8 reactivity was considerably decreased or even absent despite the presence of apparent suprabasal maturation. In differentiated squamous cell carcinomas, AE8 immunoreactivity was usually limited to a few cells in the center of the keratinized foci. However, in 10% of squamous cell carcinomas, a significant number of tumor cells was positive. Only well-differentiated urothelial carcinomas showed AE8 immunoreactivity, while poorly differentiated tumors were negative. Interestingly, a Brenner's tumor showed a high number of AE8-positive epithelial cells. Our results show that the expression of keratin 13, as immunohistochemically determined by AE8 antibody, is significantly down-regulated in squamous cell malignancies. Its possible value as an adjunct to diagnosis of dysplasia should be investigated further.

Patterns of keratin subsets in normal and abnormal uterine cervical tissues. An immunohistochemical study.

We investigated the use of three monoclonal antikeratin antibodies on routinely formalin-fixed and paraffin-embedded punch and cone biopsies of the normal human uterine cervix and its metaplastic and premalignant lesions. Monoclonal antibodies used were AE8, which is specific for keratin 13; 34BE12, which reacts with keratins of the stratified squamous epithelium; and CAM5.2, which is specific for keratin 8. All these antibodies performed well in routinely processed surgical pathology material. AE8 antibody stained the suprabasal layer of the normal squamous epithelium. Squamous metaplasia and dysplasia were stained in 50% of the cases. Normal suprabasal distribution of the keratin 13, however, was lost in all positive dysplasia cases. CAM5.2 reacted with normal columnar cells in all cases, and squamous metaplasia was focally positive in 20% of the cases. Dysplasia showed a positive reaction in 30% to 40% of the cases. The 34BE12 antibody was reacting with the full thickness of the squamous epithelium. Squamous metaplasia and dysplasia were positive in 80% of the cases. In addition, 34BE12 stained reserve cell hyperplasia, making it a useful marker for this condition. Our results demonstrate that keratin immunohistochemistry with the above-listed antibodies gives pathogenetically interesting information on cervical lesions.

Ectopic ACTH syndrome associated with ovarian steroid-cell tumor.

Several cases of ovarian neoplasms resulting in Cushing's syndrome due to ectopic secretion of ACTH or ectopic secretion of F have been reported. Tumors producing ACTH include adenocarcinoma, androblastoma, Sertoli cell carcinoma, carcinoid tumor and teratoma. Cortisol secretion has been reported in ovarian steroid cell tumor (unclassified steroid cell tumor). We present a case of a 19-year-old woman with Cushing's syndrome in course of an ovarian steroid cell tumor with ectopic ACTH production. To our knowledge, it is the first reported case of ACTH secreting ovarian steroid cell tumor causing Cushing's syndrome.

Expression of blood group antigens H-2, Le(y), and sialylated-Le(a) in human colorectal carcinoma. An immunohistochemical study using double-labeling techniques.

In this study, double-labeling immunohistochemistry was used to gain insight into the coexpression or interrelationship between blood group antigens (BGA) that are differentiation antigens in the normal colon, and BGA that are sequential moieties in the same synthetic pathway. Paired-wise Sialylated-Le(a)/Le(y) and H-2/Le(y) was studied. The Sialylated-Le(a) and Le(y) are synthesized from type 1 and type 2 backbones, respectively. In the normal colon, the Le(y) and Sialylated-Le(a) are expressed by cells at the base and surface of the crypt, respectively, representing undifferentiated and differentiated enterocytes. The H-2 is considered oncofetal in nature, and is considered to be the immediate precursor in the synthesis of Le(y). In individual cancers. Sialylated-Lea and Le(y) were detected in different cancer cells within the same malignant glands, separately in different glands, and in different subcellular compartments of the same cell. Both H-2 and Le(y) were coexpressed in the same individual cells in 92% of cancers expressing both these BGA. In 50% of the cancers, the H-2 and Le(y) also were expressed separately in different malignant glands within individual tumors. These findings indicate that, in colorectal cancers, differentiation antigens (Sialylated Le(a) and Le(y)) are expressed by different individual cells within the same malignant gland somewhat, recapitulating the normal colon crypt. Antigens of different backbones occasionally may be expressed in the same cells but within different subcellular compartments. Precursor accumulation is common in cancers, and antigens in the same synthetic pathway are coexpressed in the same cell. The expression of H-2 and Le(y) in different glands (lack of coexpression) may be explained possibly by aberrant synthesis of Le(y) by an alternate pathway.

Outcomes of vitrectomy for retained lens fragments.

PURPOSE: Retained lens fragments after cataract surgery is an infrequent, but potentially serious surgical complication. The aim of this study is to evaluate outcomes after vitrectomy has been performed for removal of retained lens material. METHODS: A retrospective review was conducted to evaluate all cases of pars plana vitrectomy for removal of retained lens fragments performed at Wills Eye Hospital from April 1991 through August 1994. RESULTS: A total of 121 eyes of 121 patients underwent pars plana vitrectomy with removal of retained lens material over the 3 1/2-year period. Visual acuity on presentation was 20/200 or worse in 95 eyes (79 percent). Visual acuity after vitrectomy was 20/40 or better in 82 eyes (68 percent). The postoperative visual acuity was 20/50 to 20/400 in 21 eyes (17 percent), and counting fingers or worse in 18 eyes (15 percent). Nineteen eyes (16 percent) had retinal detachment (RD), 8 were noted at the time of vitrectomy and 11 occurred after vitrectomy. Of the 19 eyes with RD, visual acuity was 20/200 or worse in 12 (63 percent) and counting fingers or worse in 6 (32 percent) at the time of last follow-up. The use of posterior segment phacofragmentation was associated with higher rate of RD, but the difference did not reach statistical significance. Major causes of poor final visual outcome included RD (6 eyes), cystoid macular edema (4 eyes), and glaucoma (2 eyes). CONCLUSION: The timing of vitrectomy did not have a statistically significant impact on visual outcome. Neither the type of intraocular lens nor the timing of lens implantation significantly altered the final visual acuity. Most eyes with retained lens fragments do well after vitrectomy, with the majority recovering good vision. However, the risk of RD is increased, and visual outcome may be adversely affected if RD occurs.

Chemical synthesis and expression of a calmodulin gene designed for site-specific mutagenesis.

A gene coding for a calmodulin was synthesized and expressed in Escherichia coli. The gene was produced by the enzymatic ligation of 61 chemically synthesized DNA fragments. The gene possesses 27 unique, regularly spaced, restriction endonuclease cleavage sites to facilitate gene mutagenesis by the replacement of specific gene segments with synthetic double-stranded DNA. An expression vector containing the calmodulin gene was used to transform E. coli. Purification and characterization of calmodulin (VU-1 calmodulin) expressed by these transformants showed that it lacks two posttranslational modifications: an amino-terminal blocking group and N epsilon, N epsilon, N epsilon-trimethyllysine at position 115. The cyclic nucleotide phosphodiesterase activator properties of VU-1, higher plant, and vertebrate calmodulins were not statistically different. However, VU-1 calmodulin was found to activate nicotinamide adenine dinucleotide (NAD) kinase to a maximal level that was at least 3-fold higher than that found with higher plant and vertebrate calmodulins. This higher level of activation is also characteristic of calmodulins from Dictyostelium discoideum and Chlamydomonas reinhardtii [Roberts, D. M., Burgess, W. H., & Watterson, D. M. (1984) Plant Physiol. 75, 796-798; Marshak, D. R., Clarke, M., Roberts, D. M., & Watterson, D. M. (1984) Biochemistry 23, 2891-2899]. The only common feature among Dictyostelium, Chlamydomonas, and VU-1 calmodulins not found in higher plant and vertebrate calmodulins is an unmethylated lysine at position 115. The results indicate that the lack of methylation of lysine-115 may contribute to the maximal level of NAD kinase activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Inducible nitric oxide synthase in the bladder of spinal cord injured patients with a chronic indwelling urinary catheter.

PURPOSE: Spinal cord injured patients are at increased risk for bladder carcinoma. Nitric oxide production in areas of chronic inflammation may provide a stimulus for carcinogenesis by serving as a source of nitrosating agents that generate potentially carcinogenic nitrosamines from secondary amines normally present in urine. MATERIALS AND METHODS: To determine whether inducible nitric oxide synthase is expressed as a catalyst for sustained nitric oxide production by cellular elements in chronically inflamed bladder mucosa immunohistochemical studies were performed on mucosal biopsies obtained from 37 adults with spinal cord injury. All participants had required a chronic indwelling urethral or suprapubic catheter for greater than 8 years. RESULTS: Histopathological studies revealed active inflammatory infiltrates in all 37 biopsy specimens, squamous metaplasia in 20, epithelial dysplasia in 3 and carcinoma in 1. Inducible nitric oxide synthase was detected in inflammatory cells localized to the lamina propria. Inducible nitric oxide synthase positive cells were identified as macrophages using monoclonal antibodies to macrophage antigen. There was no inducible nitric oxide synthase expression in the urothelial cell layers. Immunostaining for inducible nitric oxide synthase was not detected in bladder mucosal biopsy specimens obtained from cadaveric organ donors. CONCLUSIONS: Inducible nitric oxide synthase is expressed in inflammatory macrophages in areas of chronic inflammation in the bladder mucosa of spinal cord injured patients with a chronic indwelling bladder catheter. The expression of inducible nitric oxide synthase may potentially lead to the sustained production of nitric oxide and its oxidative products, the nitrosation of urinary amines and the formation of potentially carcinogenic nitrosamines in the bladder.