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Biomedical subjects

M May

Publications and source records attributed to M May.

At least 19 recordsLinked to original sources
PubMed1992

Influence of blood handling techniques on lactic acid concentrations.

Despite the popularity of measuring blood lactic acid concentrations, many of the common variations in technique have not been evaluated. The purposes of this study were to: 1) establish the relationship between plasma and blood lactate concentrations, 2) determine the inter-analyzer reliability, and 3) assess the stability of lactate concentration in blood stored for up to one week. Blood was sampled from 26 volunteers before exercise, at 80% of estimated maximum heart rate, and 5 minutes after a treadmill run to exhaustion. Inter-machine reliability was tested between two Yellow Springs Instruments analyzers with buffer treated with a lysing agent and between two without. Blood lactate levels at all three levels could be predicted from plasma with R2 greater than .95. Correlations between duplicates on the same machine were greater than .96 for blood and .97 for plasma. In the worst cases, between duplicate differences and between machine differences were 2%. Lactate in stored blood was in some cases significantly different after 24 hours of storage. Moderate and high lactate concentrations in plasma were not significantly altered after 2 days of storage.

Adult↗
PubMed1991

Reactivity of pretransplant cytotoxic antibodies to a selected HLA panel is not influenced by cyclosporin A, with or without plasma exchange.

The influence of 6 weeks of cyclosporin A (CYA), followed by a further 6 weeks of this agent in combination with plasma exchange (PE), was defined on panel reactivity and titre of preformed cytotoxic antibodies in stable patients on haemodialysis awaiting renal transplantation. Nine individuals with antibodies to 30% or more of the donor panel were entered into the study, but three failed to complete the programme. Comprehensive data are available on the remaining six patients, one of whom was studied twice. The pattern of reactivity to the panel was unaltered, but antibody titres were significantly reduced (P less than 0.006). In one patient, a lymphocytoxic crossmatch performed between the patient and an HLA-haploidentical sibling in the last week of the trial was positive, suggesting that neither procedure was successful in removing an antibody directed against the HLA antigens of a family donor. Three cadaver renal transplants were performed during or after the trial, and while two of the grafts were unsuccessful, one survives at 60 months, with good function. From these data it is concluded that neither cyclosporin A nor its combination with plasma exchange have any effect on the panel reactivity of preformed cytotoxic antibodies, whereas the titres were significantly reduced. An important and serious side effect of the apheresis procedure was the loss of fistulae in two patients.

Cyclosporins↗
PubMed1991

Unique topography of DNA-protein interactions in the non-coding region of epidermodysplasia verruciformis-associated human papillomaviruses.

The non-coding region (NCR) of the epidermodysplasia verruciformis (EV)-associated human papillomavirus 8 (HPV-8) has been investigated for sequence-specific DNA-protein interactions with nuclear proteins from epithelial HeLa cells. Using DNase I protection analysis 18 footprints could be found within the HPV-8 NCR, covering altogether over 60% of both DNA strands. Several footprints coincided with the known binding sites of transcription factors (NF1, AP1, octamer and PEA3 consensus sequences); the other displayed no obvious similarities in this regard. The overall distribution of sequences involved in DNA-protein interactions differed clearly from the binding patterns reported for other HPVs. Parts of the two binding sites for the viral trans-activator protein E2 were shown to interact with non-E2 factors. The EV-specific NCR motifs M33, M29 and A/T box were all involved in protein binding. By comparing the footprints within the respective motifs of the closely related types HPV-8 and -19, quantitative and qualitative differences were detected for M33 and the A/T box.

Base Sequence↗
PubMed1991

Hypoglossal-facial nerve interpositional-jump graft for facial reanimation without tongue atrophy.

The hemitongue paralysis that occurs as a result of a classic hypoglossal-facial nerve crossover procedure can result in profound functional deficits in speech, mastication, and swallowing. The procedure is not an option in patients with bilateral facial paralysis or those at risk for combined cranial nerve deficits. To address some of the drawbacks and limitations of this classic procedure, we developed the hypoglossal-facial nerve interpositional jump graft (12-7 jump graft) procedure. This procedure involves interposing a nerve graft between a partially severed but functionally intact twelfth cranial nerve and the degenerated seventh cranial nerve, and is often combined with other reanimation procedures. To date, we have performed 33 12-7 jump graft procedures in 30 patients (three were treated for bilateral facial paralysis); this report describes the procedure and its indications, and details the results of 23 procedures performed in 20 patients for whom 24-month follow-up data are available. Twelfth nerve deficits occurred in only three patients in this report. Recovery of facial function began between 3 and 24 months postoperatively. Facial tone and symmetry were achieved in every patient, no patient had significant mass movement, and 13 patients (two of whom were treated for bilateral facial paralysis) had excellent and three had superb restoration of facial movement. These results show the 12-7 jump graft to be a valuable adjunct for facial reanimation in selected patients.

Adolescent↗
PubMed1991

Differential diagnosis of facial nerve palsy.

The differential diagnosis of facial complex can be complex, but all efforts must be made to identify the cause so that appropriate treatment can be offered. This article presents a review of conditions associated with acute facial palsy and discusses the differential diagnosis of this condition. The focus is on the differentiation of other causes of acute facial palsy from the idiopathic, or Bell's type, which is a diagnosis of exclusion.

Acute Disease↗
PubMed1991

[Invariance in relation to transformations: a comparison of space perception and imagined space].

The present paper is based on the assumption of a functional equivalence between the processes of perception and imagination and a functional isomorphism between physical and phenomenal relations. The intention is to look for systematic deviations between 'measured', 'perceived' and 'imagined' space. Therefore a room was equipped with 32 pieces of furniture, giving it the appearance of a combined library and study room. A miniature model (1:10) of the room was constructed. In a two-factorial design with 10 experimental conditions, subjects performed model-reconstructions. The first factor refers to cognitive modality and represents different amounts of information of the physical layout, the endpoints of the continuum being 'complete insight' and 'no insight'. The second factor is a rotation of the model during the reconstruction (0 degrees vs. 180 degrees). Data analysis is based on location and orientation measures of the objects and distinguishes between 'semantic' and 'geometric' errors. The main results are: Even under conditions of only partial insight the spatial relations of the missing objects can be consensually reconstructed. While the absolute amount of the reconstruction errors largely depends on the two factors (modality and rotation), substantial relations of the original room are preserved under the different experimental conditions. The results are in good accordance with the assumption of functional equivalence and are critically discussed with respect to the concept of functional isomorphism.

Adult↗
PubMed1991

Gadolinium-enhanced magnetic resonance imaging of the facial nerve in herpes zoster oticus and Bell's palsy: clinical implications.

Gadolinium-enhanced magnetic resonance imaging was used in the evaluation of the facial nerve in four patients with idiopathic facial paralysis and six with herpes zoster oticus (HZO). Enhancement of the facial nerve was seen in all patients with Bell's palsy, and 50 percent of patients with HZO. The most consistent area of enhancement in both disorders involved the premeatal and labyrinthine segments. Although the images showed changes consistent with the type of viral process that is known to occur in these disorders, we found no significant correlation between the intensity or pattern of facial nerve enhancement on the images, the severity or duration of the disease, or the patient's prognosis for recovery. Nevertheless, gadolinium-enhanced MRI does have a place in the evaluation and decisions for management of select cases of facial paralysis.

Adolescent↗
PubMed1991

Sequential invasive assessment of fetal renal function and the intrauterine treatment of fetal obstructive uropathies.

Persistent fetal lower urinary tract obstruction carries a very poor prognosis secondary to damaged renal capacity and oligohydramnios, with its related pulmonary hypoplasia. Several attempts in the past several years to divert urinary flow via an intrauterine shunt have generally been disappointing, primarily because of poor patient selection. In this study we report our experiences with aggressive decompression of megacystis in 11 patients, the value in selected cases of sequential evaluations of fetal urine biochemistry, and the success of intrauterine bladder shunting procedures in appropriately chosen patients. Our data suggest that a single fetal urine determination may be insufficient to declare irreversible damage. Following decompression, improvement in urine biochemistry or its lack may be more likely representative of ultimate outcome. Decompression by either needle aspiration or intrauterine shunting is warranted in carefully selected cases and can save fetuses that are otherwise very likely doomed.

Female↗
PubMed1990

Management of the paralyzed lower eyelid by implanting auricular cartilage.

The success of a procedure to reanimate paralyzed eyelids is determined by the functional and cosmetic results. When the cornea is covered during blinking and sleeping, function has been restored, while a pleasing cosmetic result has been achieved if the eyes appear symmetrical when the lids are open. Several procedures have been developed to restore closure of the paralyzed upper eyelid (implantation of gold weights or open wire springs) or to correct lower lid lagophthalmos and ectropion (lower lid tightening with a Bick procedure or insertion of a closed eyelid spring). In some cases, even a combination of the Bick procedure and insertion of a spring may be insufficient to correct lower lid droop; therefore, we developed a technique to place cartilage into the lower eyelid to correct lid droop. The procedure, suggested by one of us (D.B.S.), has been performed on 51 patients to date. This article reviews our experience with these 51 consecutive patients.

Ear Cartilage↗
PubMed1990

Selective termination: clinical experience and residual risks.

Assisted reproductive technologies have aided thousands of couples, but complications have resulted in multifetal pregnancies creating a bitter irony for infertility patients. In an effort to increase the rate of intact survival, we have successfully performed transabdominal first-trimester selective termination procedures on 22 pregnancies including one octuplet, five quintuplet, twelve quadruplet, and four triplet gestations. There have been eight sets of twins, and two singletons delivered, seven twin pregnancies are ongoing, and one early and four late losses of pregnancies. With experience we now counsel as to a high likelihood of a technically successful procedure, but we still have concerns for late losses. We have tried to balance the arguments about the direct harms of performing selective termination and the obstetric risks of not performing selective termination. We believe that selective termination should not be considered a "social" procedure. Our data do not yet make clear whether one, two, or three is the optimal number of embryos to leave. Therefore, on the basis of both current obstetric risk factors and ethical reasoning we will continue to support our protocol of optimally leaving twins.

Abortion, Induced↗
PubMed1990

Protection from glucocorticoid induced thymic involution by dehydroepiandrosterone.

Dehydroepiandrosterone (DHEA), the most abundantly secreted human adrenal steroid, has no known specific function. In spite of this fact there is an abundance of data associating DHEA with "health" in both man and experimental animals. Research in our laboratory has demonstrated evidence for an antagonistic interaction between DHEA and glucocorticoids (GC) in liver and brown adipose tissue. We hypothesized that DHEA also antagonized effects of GC on the immune system and that this "immune protective effect" might explain the diffuse positive effects of DHEA reported in the literature. Effects of GC on the immune system include involution of the thymus when given in animals in vivo and death of thymic lymphocytes in vivo with exposure to these steroids. We hypothesized that DHEA would block this GC mediated thymocyte destruction in vivo and in vitro. Pretreatment with DHEA for three days blocked approximately 50% of the thymic involution seen with dexamethasone. Results of in vitro experiments confirmed protective effects of DHEA in pretreated animals. (less than 50% of cell death in lymphocytes from pretreated mice compared with lymphocytes from control mice.) We conclude from these studies that DHEA protects against at least one GC anti-immune effect, thymic lymphocyte lysis.

Animals↗
PubMed1990

Early facial reanimation following radical parotid and temporal bone tumor resections.

A retrospective study of 35 patients who underwent early facial reanimation following extirpative parotid and temporal bone surgery requiring facial nerve sacrifice was performed. Regional facial reanimation performed immediately or within several days included 16 patients who underwent temporalis muscle transposition and 27 who underwent gold weight or eyespring lid reanimation with lower lid tightening. Simultaneous nerve grafts or nerve crossover procedures were performed in 22 patients. The authors' favored approaches to facial reanimation are discussed, with an emphasis on the value of early reanimation using properly selected techniques.

Adult↗
PubMed1990

Lumbo-sacral chordoma with high-grade malignant cartilaginous and spindle cell components.

A recurrent lumbo-sacral chordoma with high-grade cartilaginous and spindle cell components is described. The tumor was excised from a 71-year-old man who previously had a conventional chordoma resected from his sacrum 26 years earlier. The original conventional chordoma was treated postoperatively with external beam radiation therapy, and the patient was free of disease until he presented at the age of 71 with leg weakness. Computerized tomography revealed a lumbo-sacral soft tissue mass. This was excised and found to have three distinct histologic aspects. The largest component was that of a conventional chordoma. The second component consisted of islands of malignant cartilage intimately admixed with the cells of the conventional chordoma. The third component consisted of high-grade malignant, poorly differentiated spindle cells. This case suggests that chondroid chordomas do exist and that they may also occur outside of the spheno-occipital region.

Aged↗