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At least 667 records · Page 37Linked to original sources
PubMed1992

Hair shaft elongation, follicle growth, and spontaneous regression in long-term, gelatin sponge-supported histoculture of human scalp skin.

In order to better understand the molecular mechanisms of human hair growth control and to test hair growth-modulatory drugs, appropriate in vitro models are required. Here, we report the long-term growth, shaft elongation, and spontaneous regression of human hair follicles in histoculture of intact scalp skin. Human scalp skin with abundant hair follicles in various stages of the hair growth cycle was grown for up to 40 days in a gelatin sponge-supported histoculture system at the air/liquid interface. Isolated follicles placed in the gelatin-sponge matrix also supported hair shaft elongation, with the hair follicle cells remaining proliferative and viable for very long periods. Hair shaft elongation occurred mainly during the first 10 days of histoculture of both intact skin and isolated follicles. However, hair follicles were viable and follicle keratinocytes continued to incorporate [3H]thymidine for up to several weeks after shaft elongation had ceased as shown by fluorescent-dye double staining, measured by confocal laser scanning microscopy, and by histological autoradiography of [3H]thymidine incorporation, respectively. Hair follicles could continue their cycle in histoculture; for example, apparent spontaneous catagen induction was observed both histologically and by the actual regression of the hair follicle. In addition, vellus follicles were shown to be viable at day 40 after initiation of culture. In the histocultured human scalp we demonstrated the association of mast cells with anagen follicles and macrophages with catagen follicles, suggesting a role of these cells in the hair cycle. This histoculture technique should serve as a powerful tool for future hair research in the human system as well as a screening assay for compounds that can perturb the hair cycle.

Culture Techniques↗
PubMed2006

Attention effects at auditory periphery derived from human scalp potentials: displacement measure of potentials.

It is known in humans that electrophysiological measures such as the auditory brainstem response (ABR) are difficult to identify the attention effect at the auditory periphery, whereas the centrifugal effect has been detected by measuring otoacoustic emissions. This research developed a measure responsive to the shift of human scalp potentials within a brief post-stimulus period (13 ms), that is, displacement percentage, and applied it to an experiment to retrieve the peripheral attention effect. In the present experimental paradigm, tone pips were exposed to the left ear whereas the other ear was masked by white noise. Twelve participants each conducted two conditions of either ignoring or attending to the tone pips. Relative to averaged scalp potentials in the ignoring condition, the shift of the potentials was found within early component range during the attentive condition, and displacement percentage then revealed a significant magnitude difference between the two conditions. These results suggest that, using a measure representing the potential shift itself, the peripheral effect of attention can be detected from human scalp potentials.

Acoustic Stimulation↗
PubMed2006

Scalp localization of human auditory cortical activity modified by GSM electromagnetic fields.

PURPOSE: This study attempted to determine whether there is a localized effect of GSM (Global System for Mobile communications) microwaves by studying the Auditory Evoked Potentials (AEP) recorded at the scalp of nine healthy subjects and six epileptic patients. MATERIALS AND METHODS: We determined the influence of GSM RadioFrequency (RF) on parameters characterizing the AEP in time or/and frequency domains. A parameter selection method using SVM (Support Vector Machines)-based criteria allowed us to estimate those most altered by the radiofrequencies. The topography of the parameter modifications was computed to determine the localization of the radiofrequency influence. A statistical test was conducted for selected scalp areas, in order to determine whether there were significant localized alterations due to the RF. RESULTS: The epileptic patients showed a lengthening of the scalp component N100 (100 ms latency) in the frontal area contralateral to the radiation, which may be due to an afferent tract alteration. For the healthy subjects, an amplitude increase of the P200 wave (200 ms latency) was identified in the frontal area. CONCLUSIONS: The present study suggests that radiofrequency fields emitted by mobile phones modify the AEP. Nevertheless, no direct link between these findings and RF-induced damages in brain function was established.

Adult↗
PubMed2000

A gene for hypotrichosis simplex of the scalp maps to chromosome 6p21.3.

Hypotrichosis simplex of the scalp (HSS) is an autosomal dominant form of isolated alopecia causing almost complete loss of scalp hair, with onset in childhood. After exclusion of candidate regions previously associated with hair-loss disorders, we performed a genomewide linkage analysis in two Danish families and localized the gene to chromosome 6p21.3. This was confirmed in a Spanish family, with a total LOD score of 11.97 for marker D6S1701 in all families. The combined haplotype data identify a critical interval of 14.9 cM between markers D6S276 and D6S1607. Localization of the locus for HSS to 6p21.3 is a first step toward identification of the gene. The gene will give important insights into the molecular and cellular basis of hair growth on the scalp.

Adolescent↗
PubMed2004

Influence of the scalp thickness on the intracranial contribution to rheoencephalography.

In spite of the great efforts made by the scientific community, up to now there is no agreement about the rheoencephalography (REG) capability to reflect cerebral blood flow (CBF). Moreover, a standard procedure and the optimal electrode arrangement have not been established yet. In a previous study, we found, using a classical four-shell spherical model of the head and solving it by numerical methods that, theoretically, there could exist an electrode arrangement to register an REG II free of extracranial contribution. In this paper, we have studied the influence of scalp thickness on the intracranial contribution to REG II. The study has been performed by solving the head model, using in this case analytical methods, and then estimating the partial contribution of CBF pulsatility to REG for a given set of scalp thicknesses. Although our theoretical results validate the previous finding and suggest that, in some cases, an optimal electrode arrangement to register REG II exists, such an arrangement, and even its existence, is very sensitive to the subject's scalp thickness. According to this, there could not exist a universal electrode arrangement suitable for all individuals to register an REG II free of extracranial contribution, since it depends on the subject's physical constitution. This fact could explain the lack of agreement in the literature about REG interpretation.

Brain↗
PubMed1990

Suitability of fetal scalp electrodes for monitoring the fetal electrocardiogram during labour.

As the limitations of heart-rate based intrapartum monitoring have become apparent, there is renewed interest in analysis of the fetal electrocardiographic waveform as obtained from a fetal scalp electrode. A high quality ECG signal is necessary for waveform analysis. This study examined the suitability of five commonly available scalp electrodes for collecting this signal by examining their physical and electrical characteristics, together with a randomised clinical trial in which the ECG trace quality was assessed in 50 patients. The frequency response of Copeland electrodes was such that they attenuate the ECG signal more than the baseline noise. Difficulties were experienced in obtaining optimum attachment and the long, semi-rigid design increased movement artefact resulting in significantly poorer quality ECG signals. Whilst the Hewlett-Packard double spiral electrode had a near ideal frequency response, certain design features made it difficult to apply and remain secure so the clinical signals were of intermediate quality. The Corometrics and Cetro single spirals had the most stable attachment to the scalp and a near ideal frequency response, so produced significantly better signal quality in the clinical trial. Currently, single spiral electrodes are the most suitable for electrocardiographic data collection.

Electrocardiography↗
PubMed1992

Electrical impedance tomography with cortical or scalp electrodes during global cerebral ischaemia in the anaesthetised rat.

The performance of a prototype impedance imaging (Electrical Impedance Tomography, EIT) system using cortical or scalp electrodes has been assessed in a model of global cerebral ischaemia in the anaesthetised rat. In preliminary calibration experiments using a circular array of electrodes around a tank of saline, the centre of a polythene rod could be localised with a mean error of 4% of the tank diameter, and two such rods could be discriminated when separated by 22% of the tank diameter. Cerebral ischaemia was produced by diathermy of the vertebral arteries and reversible occlusion of the common carotid arteries for 15 min. A bimodal impedance increase of about 50-200% was recorded with a ring of cortical electrodes in the fronto-occipital plane. With a similarly oriented ring of scalp electrodes, a unimodal impedance increase of about 10% was observed. In both cases, impedance reversed after cerebral reperfusion. Similar but irreversible changes were observed post mortem. As the reconstruction algorithm assumes constant initial resistivity, this suggests that modifications to allow for initial conditions would be needed for more accurate imaging with scalp electrodes.

Anesthesia, Inhalation↗
PubMedDate not supplied

Fatty Acid ethyl esters in scalp, pubic, axillary, beard and body hair as markers for alcohol misuse.

AIMS: This study examined the possibility of using hair samples other than scalp hair for analysis of fatty acid ethyl esters (FAEE) as markers for alcohol misuse. METHODS: Samples of scalp and pubic hair and, if available, axillary, beard and body hair of one teetotaller, five moderate social drinkers and 22 fatalities were analysed for FAEE by head-space solid-phase microextraction and gas chromatography-mass spectrometry. The sum of the concentrations of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate (C(FAEE)) in the hair samples was compared with information about the drinking behaviour of the individuals. RESULTS: Although there were large differences in the analyte concentrations in hair from different sites in the same individual, cases of chronic excessive alcohol consumption were characterized by C(FAEE) > 1.0 ng/mg in almost all samples. CONCLUSION: FAEE concentrations in hair other than scalp hair can be used as markers of chronic alcohol misuse.

Alcoholism↗
PubMed2005

Plasma levobupivacaine concentrations following scalp block in patients undergoing awake craniotomy.

BACKGROUND: Levobupivacaine is an effective local anaesthetic agent for nerve blockade with less systemic toxicity than racemic bupivacaine. The safety and efficacy of levobupivacaine for scalp blockade during awake craniotomy have not been addressed previously. METHODS: Serial arterial plasma levobupivacaine concentrations following scalp blockade were measured to 2 h in 10 patients booked for awake craniotomy for epilepsy or tumour surgery. Bilateral scalp blockade providing surgical anaesthesia was achieved with a mean dose of 177 mg (2.5 mg kg(-1), range 1.6-3.2 mg kg(-1)) of levobupivacaine (0.5%, 5 mg ml(-1)) with epinephrine (5 microg ml(-1)) added immediately before the block insertion. RESULTS: The maximum measured plasma levobupivacaine concentration was 1.58 (0.44) microg ml(-1) [mean (SD)] with a mean time to peak plasma concentration of 12 (4) min. There were no episodes in any of the 10 patients of symptoms or signs suggestive of either CNS or CVS toxicity. CONCLUSIONS: This study demonstrated a relatively rapid rise of plasma levobupivacaine concentration without evidence of cardiovascular or central nervous system sequelae in a sample population of patients who may be particularly prone to perioperative seizures.

Adult↗
PubMed1989

Outer table skull erosion causing rupture of scalp expander.

Many various complications have been reported with tissue expansion since it was popularized by Radovan. As expected with any foreign body implantation, the most frequent complication is infection. Rupture of the expander is relatively rare even in the face of overexpansion or blunt external trauma. Complications from tissue expansion of the scalp are similar to those encountered with the placement of expanders elsewhere in the body. We had a case recently involving rupture of an expander placed in the scalp of an 18-month-old child as a result of erosion of the outer table with bone spur formation. This was a local reaction to the pressure exerted by the expander. We present the following case report to document another potential complication with tissue expansion of the scalp.

Bone Diseases↗
PubMed1990

Avulsion of the scalp: which one is the best artery for anastomosis?

We present a patient who underwent successful replacement of a large avulsed scalp with microvascular anastomosis of one artery and three veins. The left occipital artery in the avulsed scalp and a frontal branch of a right superficial temporal artery in the recipient forehead were anastomosed. Three veins in the occipital area in the avulsed scalp were anastomosed via vein grafts to three veins in the frontal area, respectively. For successful replacement, the selection of the vessels depends on each individual case. To give easy anastomosis, a good cosmetic result, and a comfortable postoperative period, it is not always necessary to reconstruct a previously normal anatomical position.

Adult↗
PubMed1994

The surgical anatomy of the subcutaneous fascial system of the scalp.

The surgical anatomy of the fascial layers and vascularization of the scalp was studied by means of 11 bilateral cadaver dissections. This article is organized as follows: first, a description of the layers and fasciae of the scalp and their relationships with the main vascular structures, and then a description of the histological structure of the subgaleal fascia (composed of multiple connective vascularized sheets that glide over one another) and of its blood supply. In our dissections, we found the constant topographic distribution of the major perforant vessels to the subgaleal tissues as follows: in the temporal region, perforant vessels from the superficial temporal artery near and 10 to 14 cm above the zygomatic arch, where the superficial temporal artery leaves the surface of the galea to enter the superficial subcutaneous tissue, and in the fronto-parieto-occipital region, many small perforant vessels evenly entering the subgaleal plane every 5 to 10 mm. These findings could lead to greater use of fascial or composite flaps from the scalp region.

Arteries↗
PubMed1997

Calvarial deformity and remodeling following prolonged scalp expansion in a child.

A main concern in the use of scalp tissue expansion in the pediatric population has been the risk of skull deformation. Little is known about the long-term effects of tissue expansion on the skull and the ability of the skull to remodel following removal of the tissue expander. We report a recent case in which a 5-year-old boy had a fully inflated tissue expander retained under the scalp for a 15-month period. At surgery for removal of the implant the patient was noted to have a profound skull deformity characterized by severe calvarial depression and ridging. The patient underwent scalp reconstruction. Follow-up at 6 months revealed nearly complete remodeling of the skull with minimal visual deformity. This case demonstrates not only the profound bony deformity that can result from tissue expansion, but also the striking ability of the pediatric skull to remodel.

Bone Remodeling↗
PubMed1997

Treatment of giant pigmented nevus using artificial dermis and a secondary skin graft from the scalp.

From January 1994 to October 1995, 5 patients with congenital giant pigmented nevi were treated using artificial dermis with a secondary skin graft from the scalp. The nevus was excised in full thickness and the open wound was grafted with artificial dermis. About 3 weeks later, thin split-thickness skin grafting on the newly synthesized, dermis-like tissue was required. We chose the scalp as the donor of the secondary skin graft. Epithelialization of each donor site was completed within 1 week. In addition, the donor site was not complicated with alopecia or hypertrophic scars. Morbidity at the donor site was minimized and favorable tissue quality of the grafted skin was obtained. The clinical results revealed that the scalp was a favorable donor of a secondary skin graft for the treatment of giant pigmented nevus with artificial dermis.

Adolescent↗
PubMed2002

Free flaps in the treatment of locally advanced malignancy of the scalp and forehead.

Locally advanced cutaneous malignancy of the scalp and forehead is a disease that requires an aggressive approach to resection and reconstruction. Free flap reconstruction in these sites has been advocated because of the advantages of importing large amounts of well-vascularized tissue into a recipient site, which has often been compromised by previous surgery or radiotherapy. A consecutive series of 32 free flap reconstructions in 29 patients with cutaneous malignancy of the scalp and forehead was reviewed. The flap failure rate was 6% (two flaps) and the major complication rate was 10%. Of the surviving flaps, 97% (N = 29) were successful in reconstructing a challenging group of defects. Three patients developed local recurrence of the primary malignancy (mean follow-up, 21 months). The use of a broad repertoire of free tissue transfers in reconstruction of the scalp and forehead defects has allowed effective treatment of locally advanced malignancy of this region. Critical analysis of the results, however, indicates that microsurgical reconstruction is not without morbidity and that there are refinements in the diagnostic and operative steps of management that can maximize the functional and aesthetic results.

Adult↗
PubMed1998

Polarization of the human motor cortex through the scalp.

Direct currents (DC) applied directly to central nervous system structures produce substantial and long-lasting effects in animal experiments. We tested the functional effects of very weak scalp DC (< 0.5 mA, 7 s) on the human motor cortex by assessing the changes in motor potentials evoked by transcranial magnetic brain stimulation. We performed four different experiments in 15 healthy volunteers. Our findings led to the conclusion that such weak (< 0.5 mA) anodal scalp DC, alternated with a cathodal DC, significantly depresses the excitability of the human motor cortex, providing evidence that a small electric field crosses the skull and influences the brain. A possible mechanism of action of scalp DC is the hyperpolarization of the superficial excitatory interneurones in the human motor cortex.

Adult↗
PubMed2003

Dog bites of the scalp, face, and neck in children.

OBJECTIVE: To update the surgical management of injuries from dog bites of the scalp, face, and neck in children. STUDY DESIGN: Retrospective case review. METHODS: A retrospective review of 44 children with dog bites of the scalp, face, and neck was carried out at the University of New Mexico Health Sciences Center (Albuquerque, NM) between January 1, 1995, and December 31, 2000. Data on demographics, hospitalization, surgery, and outcome were collected and entered into an Access 2000 database. RESULTS: The children ranged in age from 1.0 to 12.1 years. The mean age of the study population was 5.2 years (+/-2.9 y standard deviation). Sixteen severely injured children (36%) were hospitalized to repair damage to the airway and blood vessels of the neck or to treat hemodynamic compromise. The length of stay in hospital ranged from 1 to 16 days. The most common injury in these children was a scalp laceration (57%). Twenty-six less severely injured children (64%) were not hospitalized. The most common surgery in these children (88%) was repair of multiple facial lacerations. Attention deficit hyperactivity disorder was noted in the medical records of 12 children (29%). Complications occurred in five children (31%) who were hospitalized and nine children (35%) who were not hospitalized. CONCLUSIONS: The injured child is typically a 5-year-old boy attacked by a familiar dog at home or in the local neighborhood. Children with the diagnosis of attention deficit hyperactivity disorder appear to be at a higher risk of dog bite injuries and should be monitored during interactions with dogs. The goal of surgical management for severely injured children is to avoid immediate mortality and to establish a schedule of multiple-staged procedures for revision surgeries. An optimal cosmetic result is the principal goal for less severely injured children.

Animals↗
PubMed1977

Single-stage rotation of arterialized scalp flaps for male pattern baldness: case report.

We used the Doppler ultrasonic flowmeter to trace the temporal artery and its branches posteriorly to their anastomosis with the occipital vessels. Then we outlined a scalp flap (one on each side) along the course of these vessels. The scalp flaps were raised and transposed to the anterior hairline in one stage, as treatment for male pattern baldness. There was complete survival of both flaps, with immediate, normal, luxuriant growth of hair--which could be combed to cover the entire scalp.

Alopecia↗