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At least 577 records · Page 32Linked to original sources
PubMed1998

Ultrastructure of human scalp hair shafts as revealed by freeze-substitution fixation.

Human scalp hair is important as a diagnostic clue to many diseases, in medical jurisprudential investigations, and also as a subject of cosmetic treatments. While many ultrastructural studies of the human hair root including the hair follicle have been reported, few studies have been done on the human hair shaft. We report here the ultrastructure of human scalp hair shafts prepared by a rapid-freezing technique followed by freeze-substitution fixation that allows the observation of fine cell structures. Healthy scalp hair shafts from Japanese females 12-13 years of age were rapid-frozen and then freeze-substituted in OsO4-acetone. In addition, this technique was applied to the study of some changes of the hair shafts (i.e., hair damaged by thioglycolic acid cold permanent waving and white hair). By this method, the hair shaft was rapid-frozen throughout without appreciable ice damage although the hair shaft was nearly 100 microm in diameter. The rapid-freezing technique resulted in excellent preservation of the ultrastructure of the hair shafts: lamellar structures in the cuticle and fine fibrous ultrastructures in the cortex were observed without chemical treatments. Thioglycolic acid treatment affected the ultrastructure of both the cuticle and the cortex. Except for the absence of melanin granules, no significant differences in the ultrastructure were observed between white hair and black hair. The rapid-freezing technique followed by freeze-substitution fixation appears to be the most reliable approach for the morphological evaluation of fully keratinized cells and tissues.

Adolescent↗
PubMed2001

Fine-needle aspiration diagnosis of unusual cutaneous neoplasms of the scalp in HIV-infected patients: a report of two cases and review of the literature.

We report on two unusual, non-AIDS-defining scalp neoplasms, Merkel-cell carcinoma (MCC) and malignant melanoma, in 2 men with acquired immunodeficiency syndrome (AIDS). In the first patient, metastatic MCC was initially diagnosed by fine-needle aspiration (FNA) of a posterior cervical lymph node, based on the cytomorphology and the characteristic immunohistochemical and ultrastructural features. No skin lesion was initially apparent, but a 0.3-mm scalp primary was found during the ensuing neck dissection. In the second patient, recurrent and metastatic malignant melanoma from a Breslow 1.3-mm scalp primary was diagnosed by FNA. Both patients developed generalized disease in a relatively short time, despite their small primaries. These cases illustrate the occurrence of Merkel-cell carcinoma and melanoma in AIDS patients, and stress the need to consider these unusual cutaneous neoplasms when evaluating lymph node FNA samples from HIV-positive patients, especially since both may present as metastases from clinically occult primaries.

Biopsy, Needle↗
PubMed1988

Congenital scalp defects with distal limb anomalies (Adams-Oliver syndrome): report of ten cases and review of the literature.

We describe one family with 5 affected persons in 4 generations, another family with 2 affected brothers and 3 sporadic cases of the rare syndrome of congenital scalp defects with distal limb deficiency. The manifestations of this syndrome are highly variable. Review of the literature showed 11 families and 19 sporadic cases. In most families the disorder clearly follows an autosomal dominant pattern of inheritance, but in some families with reduced penetrance. Important differential diagnoses are the syndrome of scalp defect and postaxial polydactyly, the syndrome of scalp defect and split-hand defect, amniotic band sequence, and epidermolysis bullosa dystrophica type Bart.

Female↗
PubMed1991

Hereditary hypotrichosis of the scalp.

Hypotrichosis of the scalp was found in 4 individuals of a 6-generation Caucasian family. This congenital phenomenon is a rather rare subtype of hereditary hypotrichosis and affects only scalp hair. The hairs of the scalp were generally sparse and short vellus type from childhood and thinned progressively with age. Morphologic studies showed poor imbrication of cuticles and dysplastic bulbar structure of the anagen follicles. The density of hair follicles per/cm2 area was comparatively lower than that of normal individuals. The genealogical study and histomorphometrical findings of this autosomal dominant trait are discussed along with previously reported causes of hypotrichosis.

Adult↗
PubMed2005

Hypothelia, syndactyly, and ear malformation--a variant of the scalp-ear-nipple syndrome?: Case report and review of the literature.

The scalp-ear-nipple syndrome is a rare autosomal dominant condition that involves lesions of the scalp, malformed external ears, and absence of rudimentary nipples and breasts. We report a case of a woman with hypothelia, bilateral mildly malformed ears, and syndactyly of the hands and feet, and review the literature on the hypothelia/athelia phenotype. This case may represent a mild phenotype of the scalp-ear-nipple syndrome or a newly recognized entity.

Abnormalities, Multiple↗
PubMed2001

Atypical fibroxanthoma of the scalp.

BACKGROUND: Atypical fibroxanthoma occurs most frequently in the head and neck region of the elderly. Previous reports have identified that the condition usually arises at the following sites: the nose, cheeks, forehead, and the ears; its development at other sites is unusual. METHOD: We report a series of 10 cases with lesions all occurring at an apparently unusual site, the scalp, over a 10-year period. We compared the clinical and histologic appearances and behavior of this series with the existing reports of these lesions elsewhere in the head and neck region to investigate whether there were differences with those occurring at a conventional site. RESULTS: Despite the identification of a range of clinical and histologic findings in our cases, we were unable to find any significant differences with those arising at a conventional site. CONCLUSION: This clustering of cases at an apparently unusual site leads us to propose that this condition occurs more commonly on the scalp than current literature suggests. The possibility of its development at this site should be remembered by head and neck surgeons in their differential diagnosis of exophytic lesions of the scalp.

Aged↗
PubMed1993

Total scalp replantation based on one artery and one vein.

A successful replantation of a totally avulsed scalp, including both eyebrows, with only one arterial and one venous anastomosis to the superficial temporal vessels is described. Apart from a small partial skin necrosis of the right eyebrow, the entire transplant survived. Subsequently, the patient required only minor additional skin grafting, correction of scars with a skin expander, and reconstruction of the eyebrow with hair micrografts. Replantation of the total scalp based on two or more vessels has previously been recommended and reported elsewhere. In the present case, complete survival of the scalp on only one artery and one vein was demonstrated, indicating that replantation should be considered even if available vessels for anastomosis are minimal.

Adult↗
PubMed1994

Microvascular replantation of a completely avulsed scalp.

Total scalp avulsion is an unusual injury. To obtain good functional and cosmetic results, immediate revascularization using microsurgical techniques and replacement of the scalp in the correct anatomical position is the procedure of choice. This article describes a case report of successful replantation of a totally avulsed scalp from a 26-year-old male. Bilateral superficial temporal vessel anastomoses were performed using reversed autologous long saphenous vein grafts on the right side and direct repair on the left. Points of technique are discussed and the literature is reviewed.

Accidents, Occupational↗
PubMed2002

Modality-related scalp responses after electrical stimulation of cutaneous and muscular upper limb afferents in humans.

To elucidate whether the selective electrical stimulation of muscle as well as cutaneous afferents evokes modality-specific responses in somatosensory evoked potentials (SEPs) recorded on the scalp of humans, we compared scalp SEPs to electrical stimuli applied to the median nerve and to the abductor pollicis brevis (APB) motor point. In three subjects, we also recorded SEPs after stimulation of the distal phalanx of the thumb, which selectively involved cutaneous afferents. Motor point and median nerve SEPs showed the same scalp distribution; moreover, very similar dipole models, showing the same dipolar time courses, explained well the SEPs after both types of stimulation. Since the non-natural stimulation of muscle afferents evokes responses also in areas specifically devoted to cutaneous input processing, it is conceivable that, in physiological conditions, muscle afferents are differentially gated in somatosensory cortex. The frontocentral N30 response was absent after purely cutaneous stimulation; by contrast, it was relatively more represented in motor point rather than in mixed nerve SEPs. These data suggest that the N30 response is specifically evoked by proprioceptive inputs.

Adult↗
PubMed1996

Dermal papilla cells derived from beard hair follicles secrete more stem cell factor (SCF) in culture than scalp cells or dermal fibroblasts.

As stem cell factor (SCF) and its receptor, c-kit, are involved in hair pigmentation, SCF is probably produced in the skin, possibly by the regulatory follicular dermal papilla. Since androgens often alter the type and color of hair, probably via the dermal papilla, they may regulate its SCF production. SCF produced by beard and non-balding scalp dermal papilla cells in the presence, or absence, of 10nM testosterone was assayed by ELISA. After 24 h, beard cells produced significantly (p = 0.001) more SCF than scalp cells, while beard and scalp fibroblasts secreted significantly (p = 0.04) less SCF. Testosterone in vitro had no effect on SCF secretion. These results support the hypotheses that the dermal papilla is a local source of SCF in hair follicles and that androgens would alter SCF production only at specific points of the hair cycle.

Cells, Cultured↗
PubMed1987

Different scalp localization of pattern onset and reversal visual evoked potentials.

Visual evoked potentials were recorded monopolarly from seven electrodes on a horizontal line from T3 to T4 and bipolarly in one channel from left of the midline to right of the midline. Stimulation of the right and left half-fields was performed with a checkerboard generator of 10 degrees x 13.5 degrees and checks of various sizes at high contrast. The results may be summarized as follows: 1. Source-sink analysis for lateral half-field pattern onset with small checks shows C1, peaking about 80 msec, to have a source on the scalp contralateral to the half-field stimulated with a sink on the midline. 2. To half-field pattern reversal, bipolar recording across the scalp midline indicates an early phase reversal peaking about 80 msec followed by another phase reversal peaking at about P100 latency. Source-sink analysis indicates the first reversal has a contralateral source, while the second has a source on the scalp midline or ipsilateral to the field stimulated. 3. Pattern reversal results vary with check size, with a smaller check size increasing the amplitude of the first phase reversal and decreasing the amplitude of the second.

Evoked Potentials, Visual↗
PubMed1993

The influence of stimulus orientation on the vertex positive scalp potential evoked by faces.

The scalp-recorded "vertex-positive peak" (VPP) evoked by images of faces in humans has previously been shown to be delayed when an originally upright stimulus is inverted or rotated by 90 degrees (Jeffreys 1989a). This paper describes a study of the effects on this scalp potential of smaller face orientation changes (15 degrees increments). The results showed that, under normal viewing conditions of clearly defined facial images, the VPP latency, which was minimal for face orientations within 15 degrees of the vertical (0 degree), increased almost linearly for incremental rotations from 15 up to 90 degrees, but was relatively unchanged or decreased slightly for further rotations from 90 up to 180 degrees. Similar results were observed for clockwise and anticlockwise rotations, and for different facial representations. These stimulus orientation changes did not change the latency of simultaneously recorded, pattern-specific potentials recorded from occipital scalp locations; nor did they greatly affect the VPP amplitude. By contrast, rotations of "Mooney figure" stimuli away from the vertical produced concurrent reductions in both the perception of a face and the amplitude of the evoked VPP. Experiments in which the orientation of both the stimulus face and the subject's head were varied further showed that minimal latency VPP responses were evoked for parallel stimulus and viewing orientations. The speed of response is thus determined by the orientation of the subtended retinal image.

Adult↗
PubMed1990

Organ culture of human scalp hair follicles: effect of testosterone and oestrogen on hair growth.

Whole human scalp hair follicles were cultured. The follicles were dissected from skin pieces of normal scalp and put into 1.5 ml of incubation medium in a closed 5 ml glass tube under an atmosphere of 95% O2 and 5% CO2. The tube was rolled at 15 rpm at 36 degrees C. Remarkable hair growth was noticed for 7 to 8 days. Hair root sheaths also grew with the hair shafts. The structure of the hair bulbs was well maintained for at least 6 days, and then the hair matrix cells started to degenerate. Fetal calf serum was not essential for hair growth in vitro, but increased the growth rate slowly. Testosterone and oestrogen inhibited hair growth in vitro to a similar extent. The minimum effective doses of both hormones to suppress hair growth were around 5 ng/ml, which corresponds well to the normal plasma level of testosterone in adult males in vivo, suggesting that scalp hair growth may be critically controlled by testosterone in adult males.

Autoradiography↗
PubMed1977

On the physiology and biochemistry of the scalp and hair lipids.

Analyses were made of the scalp and hair lipids of 67 test persons. These were the most important results: 1. Seborrhoea is caused on one hand by a high secretion performance of the sebaceous glands. A further cause is that a longer period of time passes before a constant lipid amount is established. 2. There was an average of 19.32% of free fatty acids in the scalp and hair lipids on the 1st day after the hair was washed, and 38.68% on the 10th day. These results allow an assessment of the physiological significance of microbial lipolysis outside the secretory ducts of the sebaceous glands. 3. On the hairy head the percentage of free fatty acids in the scalp and hair lipids is independent of the amount of lipids. Such a difference in the concentration of fatty acids as is found between seborrhoea oleosa and seborrhoea sicca on hairless skin can not be found on the hairy head.

Adolescent↗
PubMed1995

Human scalp hair follicle development from birth to adulthood: statistical study with special regard to putative stem cells in the bulge and proliferating cells in the matrix.

The depths of hair follicle compartments, and in particular of the bulge, the putative site of hair follicle stem cells, have not yet been determined in human scalp skin from infants, children or adolescents. This information is necessary in order to use the scalp safely as a donor site for skin grafts. We therefore investigated the development of the infundibulum, the bulge, Adamson's fringe, the B-fringe and the matrix by measuring the depths of these five follicular compartments in parietal scalp biopsy specimens from 100 patients ranging in age from 2 weeks to 21 years. The thickness of the epidermis and the dermis were also assessed. The correlations of these measurements with age were determined by regression analysis. The regression equation for the bulge was found to be b (microns) = 683.3 + 30.8y (r = 0.73; SEM = 145.5) where y is the age in years, and for the matrix it was m (microns) = 1616.2 + 90.4y (r = 0.76; SEM = 406.5); P < 0.0001 for the null hypothesis. The growth of the inferior portion below the bulge was not parallel but proportional to that of the superior portion. The relative position of the bulge in the dermis was stable, whereas the inferior portion moved progressively more deeply into the subcutis. These findings provide evidence for the postulated biologically advantageous localization of the bulge, and thus is a further argument in favour of the bulge as the site of follicular stem cells.

Adolescent↗
PubMed1993

Ocular artifacts in EEG and event-related potentials. I: Scalp topography.

The ocular artifacts that contaminate the EEG derive from the potential difference between the cornea and the fundus of the eye. This corneofundal or corneoretinal potential can be considered as an equivalent dipole with its positive pole directed toward the cornea. The cornea shows a steady DC potential of approximately +13 mV relative to the forehead. Blink potentials are caused by the eyelids sliding down over the positively charged cornea. The artifacts from eye-movements result from changes in orientation of the corneo-fundal potential. The scalp-distribution of the ocular artifacts can be described in terms of propagation factors--the fraction of the EOG signal at periocular electrodes that is recorded at a particular scalp location. These factors vary with the location of the scalp electrode. Propagation factors for blinks and upward eye-movements are significantly different.

Adolescent↗
PubMed2001

Age-associated changes in integral cholesterol and cholesterol sulfate concentrations in human scalp hair and finger nail clippings.

In contrast to surface lipids originating from the sebaceous glands, membrane-forming integral lipids occur in keratinized tissues of skin, and skin appendages like fingernail plates or scalp hair. After removal of lipids of sebaceous origin by exhaustive solvent extraction, lyophilizing and hydrolyzing fingernail plate and scalp hair samples, fractions of integral cholesterol (CH) and cholesterol sulfate (CS) were quantified using gas chromatography. We studied these bound lipids and the serum lipids of 70 healthy subjects, aged 20.1 to 92.0 years. We observed higher amounts of CS in hair clippings of men than of women (775+/-241 vs 662+/-239 nmol/g hair, respectively). The highest amounts of CS were found in men with serum LDL-CH > 4.14 mmol/L; this subgroup also showed the highest CH values in fingernail clippings (2293+/-621 nmol/g nail). However, analysis of integral lipids of hair and fingernail plate clippings had little significance in detecting hypercholesterolemia in normal persons. An increase in integral CH levels in fingernail clippings with donor age was noted, independently of variations in serum CH or LDL-CH. This correlation proved to be significant in men (R=0.43), but not in women (R=0.38). In contrast, in women but not in men we found donor age correlated with internal CH of hair samples (R=0.43) and with CS of nail plates (R=-0.59), independently of serum CH or LDL-CH variations. This age-dependent decrease in CS levels might explain the previously observed higher incidence of brittle nails in women. Obviously, the metabolism of internal lipids CH and CS in fingernail and scalp hair differs between genders, and shows age-associated changes.

Adult↗
PubMed1998

Dipolar sources of the early scalp somatosensory evoked potentials to upper limb stimulation. Effect of increasing stimulus rates.

Brain electrical source analysis (BESA) of the scalp electroencephalographic activity is well adapted to distinguish neighbouring cerebral generators precisely. Therefore, we performed dipolar source modelling in scalp medium nerve somatosensory evoked potentials (SEPs) recorded at 1.5-Hz stimulation rate, where all the early components should be identifiable. We built a four-dipole model, which was issued from the grand average, and applied it also to recordings from single individuals. Our model included a dipole at the base of the skull and three other perirolandic dipoles. The first of the latter dipoles was tangentially oriented and was active at the same latencies as the N20/P20 potential and, with opposite polarity, the P24/N24 response. The second perirolandic dipole showed an initial peak of activity slightly earlier than that of the N20/P20 dipolar source and, later, it was active at the same latency as the central P22 potential. Lastly, the third perirolandic dipole explaining the fronto-central N30 potential scalp distribution was constantly more posterior than the first one. In order to evaluate the effect of an increasing repetition frequency on the activity of SEP dipolar sources, we applied the model built from 1.5-Hz SEPs to traces recorded at 3-Hz and 10-Hz repetition rates. We found that the 10-Hz stimulus frequency reduced selectively the later of the two activity phases of the first perirolandic dipole. The decrement in strength of this dipolar source can be explained if we assume that: (a) the later activity of the first perirolandic dipole can represent the inhibitory phase of a "primary response"; (b) two different clusters of cells generate the opposite activities of the tangential perirolandic dipole. An additional finding in our model was that two different perirolandic dipoles contribute to the centro-parietal N20 potential generation.

Adult↗