PubMed Health⌕ Search

Biomedical subjects

J Lugo

Publications and source records attributed to J Lugo.

15 recordsLinked to original sources
PubMed2004

The relationship between temperature and neuronal characteristics.

The purpose of this study was to determine a relationship between surface temperature of the limb and neuronal characteristics of the median and ulnar nerves in non-impaired individuals. Previous literature demonstrates that there is a negative correlation between distal latency and amplitude and temperature while a positive correlation exists between nerve conduction velocity and temperature. It is a common clinical practice to externally manipulate the temperature of a cold limb. Thirty-six participants (21 male, 15 female,) with an age range between 20-38 years old (mean age = 26.6) completed the study. Temperature of the limb was not manipulated by the researchers prior to testing and was measured at the distal wrist crease using a surface probe. Relationship was determined using a Pearson product-moment coefficient of correlation. A significant negative correlation existed for median distal sensory latency (DSL), ulnar DSL, ulnar motor amplitude (CMAP), and ulnar sensory amplitude (SNAP). The investigators conclude that temperature is a factor to consider when performing nerve conduction studies. The researchers suggest using mathematical correction factors to compensate for a cool limb rather than external heating.

Adult↗
PubMed1998

Benefits and costs to community-based physicians teaching primary care to medical students.

The purpose of this study was to determine the benefits and costs to community-based primary care physicians teaching medical students in their offices. Survey data were collected from 185 preceptors between 1990 and 1996. Respondents reported increases in their enjoyment of the practice of medicine (82%), time spent reviewing clinical medicine (66%), desire to keep up with recent developments in medicine (49%), and patients' perception of their stature (44%). However, 61% reported a decrease in the number of patients seen when a student was present. We conclude that despite the costs associated with teaching medical students in their offices, preceptors derived many benefits.

Clinical Clerkship↗
PubMed1997

Differential expression of the intermediate filament peripherin in cutaneous neural lesions and neurotized melanocytic nevi.

Peripherin is an intermediate filament involved in growth and development of the peripheral nervous system, and is produced by neurons and the beta cells of the islets of Langerhans. Recently, malignant melanomas and some melanocytic nevi have been shown to express peripherin. It is unknown if Schwann cells, also derived from the neural crest, express peripherin. Expression of peripherin was evaluated by immunohistochemistry in cutaneous lesions characterized by a prominent Schwann cell component including 26 neurofibromas (NF), 10 schwannomas (SCH), seven granular cell tumors, and five palisaded encapsulated neuromas (PEN); 13 neurotized melanocytic nevi (NMN) also were evaluated because these lesions contain Wagner-Meissnerlike structures and type C nevus cells, which exhibit a "schwannian" phenotype. Peripherin was detected in the axons of normal peripheral nerves. NF and PEN contained numerous axons dispersed throughout the lesions, whereas only scattered small nerves were seen in GCT. In SCH, only rare axons were labeled, mostly at the periphery of the lesions. All other cells in these four types of lesions, therefore including Schwann cells, were not labeled. In most NMN, labeled axons were identified within the lesions. In a few cases, rare epithelioid melanocytes within the superficial portions of the nevi were labeled. The Wagner-Meissnerlike structures and type C nevus cells (schwannian) were not labeled in any lesion; however, numerous labeled axons invested these areas. Because there are different relative numbers of peripherin-labeled axons throughout NF, PEN, some nevi, and SCH, analysis of peripherin expression may be helpful in the diagnosis of these lesions. Neurons and some epithelioid melanocytes, in contrast to type C nevus cells and Schwann cells of NF and SCH, express peripherin, providing further evidence for a transition from a more neuronal to a more schwannian phenotype during the normal maturation sequence of melanocytes in nevi.

Axons↗
PubMed1997

The intermediate filament peripherin is expressed in cutaneous melanocytic lesions.

Peripherin is an intermediate filament involved in growth and development of the peripheral nervous system and is localized to neurons, some other cells derived from neural tube and neural crest, and some neuroendocrine cells (e.g. beta cells of islets of Langerhans). Peripherin also has been demonstrated in neuroblastomas and cutaneous neuroendocrine (Merkel cell) carcinomas. The expression of peripherin by other cells derived from the neural crest is unknown. We evaluated by immunohistochemistry 74 cutaneous melanocytic lesions including primary invasive malignant melanoma (IMM), melanoma in situ (MIS), atypical nevus (nevus with architectural disorder and cytologic atypia of melanocytes) (AN), spindle and epithelioid cell nevus (Spitz nevus) (SN), blue nevus (BN), and common intradermal benign melanocytic nevus (BMN) for expression of peripherin. Peripherin was detected in a cytoplasmic distribution within tumor cells in 14/14 IMM and 8/10 MIS. For IMM, peripherin localized to both the intraepidermal and invasive dermal components. Peripherin was detected in 10/10 AN and 9/9 SN, being localized to the intraepidermal component and, focally, to the superficial dermal component of the lesions. The dendritic nevus cells in 15/15 BN also expressed peripherin. For most of the BMN, expression of peripherin was absent or limited to rare, scattered cells in the superficial portion of the lesions. Melanocytes in adjacent normal skin were not labeled in any of the lesions studied. These results indicate that expression of peripherin is common in both benign and malignant melanocytic lesions, but not in normal resting adult melanocytes. Among benign lesions, expression of peripherin in the dermal component is rare except in the dendritic cells of BN. These findings provide evidence that the expression of peripherin, a marker of neuronal differentiation, is maintained by IMM, MIS, and BN, but is lost in the normal maturational sequence of the dermal component of other melanocytic lesions.

Adult↗
PubMed1996

CD34-reactive fibrous papule of the nose.

In human skin, the CD34 antigen is expressed on endothelium, periadnexal cells, and a population of reticular dermal interstitial cells. CD34 expression is characteristic of dermatofibrosarcoma protuberans and several other neoplasms, but not of typical fibrous papules of the nose. We describe a 16-year-old white girl with a slowly growing papule on the nose. Histopathology showed a dermal tumor with a superficial component of branched, thin-walled blood vessels and a deeper component of benign-appearing, spindle-shaped cells. These cells uniformly and strongly expressed CD34, but not factor XIIIa or markers of melanocytic, neural, muscular, vascular, or histiocytic differentiation. We consider this lesion a CD34-reactive fibrous papule. This benign tumor must be clearly distinguished from dermatofibrosarcoma protuberans, which also is composed of bundles of CD34-reactive spindle-shaped cells in most cases but has locally aggressive behavior.

Adolescent↗
PubMed1996

Intermediate- and low-molecular-weight keratin detection with the monoclonal antibody MNF116. An immunohistochemical study on 232 paraffin-embedded cutaneous lesions.

Immunohistochemical detection of certain low to intermediate molecular weight keratins often is impaired in routinely processed specimens due to masking of these antigens by formalin fixation. Despite standard enzymatic digestion, AE1:AE3 and CAM 5.2, two of the most currently utilized antikeratin antibody preparations, either stain weakly or fail to stain basal keratinocytes and tumors composed of basaloid keratinocytes in paraffin sections of formalin-fixed tissue. We present here our experience with the monoclonal antibody MNF116 which detects keratins 5, 6, 8, 17, and 19 (DAKO, Carpinteria, CA). We have studied 232 routinely-processed skin lesions with MNF116 and compared the staining with that of AE1:AE3 mixture or CAM 5.2. In normal skin, the staining achieved with MNF116 was particularly strong on the basal cells of the epidermis and adnexae. MNF116 was positive in all 154 epithelial tumors and negative in all but one (a leiomyosarcoma) of 78 mesenchymal and melanocytic tumors. AE1:AE3 mixture was positive in all but four poorly-differentiated squamous cell carcinomas and it was only weakly positive in most basal cell carcinomas. CAM 5.2 was positive in tumors of the sweat apparatus, Merkel cell carcinomas, metastatic carcinomas, and 5/15 basal cell carcinomas. We consider that, in routinely processed specimens, MNF116 is very useful and convenient for detection of cytokeratin expression in cutaneous lesions, and therefore helpful in the evaluation of tumors with small cells and other poorly differentiated neoplasms of the skin.

Antibodies, Monoclonal↗
PubMed1995

Angiotropic metastatic malignant melanoma.

Three years after excision of a primary malignant melanoma from the lower back, a mass was noted in the right scapular region of a 51-year-old man. Histopathology revealed a malignant spindle-cell neoplasm invading the wall of a deep cutaneous blood vessel. Immunohistochemistry confirmed the diagnosis of angiotropic metastatic melanoma and ruled out primary leiomyosarcoma. Angiotropism is a rare pattern of metastasis of melanoma; the biochemical mechanisms that permit melanoma cells to undergo hematogenous dissemination, and the favorable milieu that the vascular wall offers for melanoma cells, may be responsible for this unusual growth pattern.

Blood Vessels↗
PubMed1995

Differential expression of CD44 in malignant cutaneous epithelial neoplasms.

The CD44 antigen (ECMRIII, Hermes antigen) is a highly glycosylated cell-surface polypeptide involved in diverse cellular functions, including cell adhesion and lymphocyte-homing receptor activity. CD44 is also expressed in vivo by several tumors, including astrocytomas, meningiomas, and colonic adenocarcinomas. In addition, it has been shown that expression of CD44 appears to confer metastatic potential to cell lines derived from certain adenocarcinomas. In the skin, CD44 is normally expressed in epidermal keratinocytes and hair follicular, sebaceous, and eccrine epithelial cells. However, there have been few data with regard to the expression in vivo of CD44 in primary cutaneous neoplasms. Furthermore, there have not been studies in vivo of the possible differential expression of CD44 in primary versus metastatic tumors in the skin. We have examined by immunohistochemistry the expression of CD44 in cutaneous invasive and metastatic squamous cell carcinomas, metastatic adenocarcinomas, and basal cell carcinomas. All invasive and metastatic squamous cell carcinomas, as well as metastatic adenocarcinomas, strongly expressed CD44; however, basal cell carcinomas were nonreactive or showed only focal, minimal reactivity. Adjacent normal skin demonstrated CD44 immunoreactivity throughout the epidermis, including the basal layer. In addition, hair follicles and sebaceous and eccrine glands expressed CD44. The results suggest that expression of CD44 in these cutaneous epithelial tumors is not related to malignant transformation, but instead may be related to tumor progression and the ability to metastasize.

Adenocarcinoma↗
PubMed1995

Nevoid malignant melanoma: morphologic patterns and immunohistochemical reactivity.

The term "nevoid malignant melanoma" (nevoid MM) is used here to describe rare nodular malignant melanomas that may escape detection in routine histological sections due to the lack of a prominent intraepidermal component, sharp lateral circumscription and evidence of partial maturation with descent in the dermis. Nevoid MM mimic ordinary compound or intradermal melanocytic nevi when the melanoma cells are small, or Spitz's nevi when the cells are large. The patterns of HMB-45 staining in 12 nevoid MM were compared with those in 107 melanocytic nevi. HMB-45 staining was strong in the dermal component of the nevoid MM, even in the absence of a junctional component. In common acquired and congenital nevi, the upper dermal component stained less than the junctional component of the lesion. The deepest components of these nevi were negative. Spitz nevi and cellular blue nevi had positive dermal cells, even without a junctional component. Additional staining for a proliferation marker, such as cyclin (PCNA) or Ki-67 (with the antibody MIB-1), can help further in distinguishing a nevoid MM from a Spitz's nevus. Melanoma has strong nuclear staining throughout the lesion. In contrast, Spitz's nevi have more staining at the top of the lesion than at the bottom. The patterns of HMB-45 and MIB-1 staining can be used along with standard histologic criteria for the diagnosis of nevoid MM. Clinicopathologic correlation is needed to distinguish some metastatic melanomas from primary nevoid MM.

Adult↗
PubMed1992

Cutaneous manifestations of measles in AIDS.

In immunocompetent patients, infection by the measles (rubeola) paramyxovirus produces fever, cough, coryza, Koplik's spots, and, on the skin, a macular erythema that can become confluent. The erythema has a striking cephalocaudal spread and clearing. The diagnosis of measles on a skin biopsy and the distinction from an erythema multiforme type of drug eruption can be difficult. We studied a skin biopsy from a patient with the acquired immunodeficiency syndrome (AIDS) who presented with measles. In contrast to erythema multiforme, the measles biopsy has necrosis of clusters of keratinocytes in the high spinous layer and granular layer of the epidermis, whereas erythema multiforme has necrosis of basal keratinocytes. Multinucleated keratinocytes may or may not be prominent in the measles biopsy. Cytoplasmic swelling of the keratinocytes in the granular layer may be present even when multinucleated cells are sparse. Immunoperoxidase reactivity for measles virus protein is present in intranuclear inclusions and in the cytoplasm of infected upper spinous keratinocytes. There were more cells with positive staining in the biopsy from the AIDS patient than in another biopsy from an immunocompetent patient with measles. The AIDS patient was seronegative for measles throughout the course of the illness. The examination of the skin biopsy can be very important in the diagnosis of measles in AIDS patients or immunocompromised patients who may not develop the usual diagnostic serology.

AIDS-Related Opportunistic Infections↗
PubMed1992

Presence of Aedes (Gymnometopa) mediovittatus in Cuba: a new factor to be considered in the national campaign to eradicate dengue.

To assess the presence of the potential dengue vector Aedes mediovittatus relative to other mosquito species, data were examined from 44,199 larvitraps operating between January 1984 and December 1987 in the town of Mariel, Cuba. Of 1,068 larvitraps containing mosquitoes, 626 (58.6%) were positive for Ae. mediovittatus. Its relative presence increased each year except 1986, going from 37.9% of the positive traps in 1984 to 70.2% in 1987. More larvitraps were positive for Ae. mediovittatus than for Culex quinquefasciatus, which typically dominated breeding sites at the end of the intensive phase of the national campaign against Ae. aegypti in the early 1980s. The results appear to reflect Ae. mediovittatus' gradual infiltration into areas covered by the campaign, a factor that may need to be considered in efforts to control dengue in the Americas.

Aedes↗
PubMed1992

Overexpression of p53 protein in basal cell carcinomas of human skin.

Basal cell carcinoma (BCC) of the skin is the most common human cancer, but its molecular-genetic pathogenesis is unclear. In many other types of cancer, mutations of the tumor-suppressor gene p53 occur frequently and may lead to overexpression of a long-lived mutant form of p53 protein. In this study, overexpression of p53 protein was detected immunohistochemically in 30 (83%) of 36 specimens of BCC of the head and neck. The same regions of tumor typically were reactive both with a monoclonal antibody (PAb240) specific for the mutant protein and with one (PAb1801) directed against an epitope common to both wild-type and mutant p53 protein. Keratinocytes of chronically sun-exposed epidermis adjacent to BCCs also focally overexpressed p53 protein in the majority of cases, whereas those of sun-protected buttock skin did not. Mutation of p53 may form an important part of the pathogenetic sequence in a majority of cases of BCC.

Adult↗
PubMedDate not supplied

Neuronal conduction studies of the median nerve in non-impaired humans: a comparison of accepted techniques.

BACKGROUND AND PURPOSE: There are two commonly accepted techniques used for distal electro-stimulation placement when performing median motor nerve conduction studies. The purpose of this study was to compare latency using two commonly accepted sites of distal stimulation of the median nerve when performing motor nerve conduction studies on non-impaired adult humans. PARTICIPANTS: The sample consisted of 36 non-impaired participants (15 female, 21 male) aged 20 to 40 years. METHODS: Participants were randomly assigned to two groups and tested bilaterally for the median motor nerve. For distal stimulation of the median motor nerve, in the first group, 8 cm was measured from the center of the muscle diagonally to arrive at a point between the flexor carpi radialis and plamaris longus tendons. In the second group, 3.5 cm was measured from the distal wrist crease proximally along the median nerve for the distal stimulation of the median motor nerve. Distal latency of both techniques was obtained. Surface skin temperature of the palm was recorded throughout the procedures. RESULTS: No significant differences were found between the 8 cm and 3.5 cm techniques at p < or = 0. 05 level. COMMENT: Even though no differences were found between the two techniques, the 3.5-cm technique is recommended because of its consistency as an anatomical landmark reducing the potential for measurement error.

Adult↗