Biomedical subjects

D H Han

Publications and source records attributed to D H Han.

At least 19 recordsLinked to original sources

PubMed2006

Embolization of wide-necked aneurysms with using three or more microcatheters.

BACKGROUND: A new and relatively simple endovascular technique, in which more than three microcatheters are used for endovascular treatment of cerebral aneurysms for the first time, is described. METHOD: Eight patients with wide necked aneurysms were successfully treated with detachable coils using the multiple microcatheter technique. Three patients presented with subarachnoid haemorrhage and five were unruptured. The aneurysm locations were superior hypophyseal artery (2), posterior communicating artery (2), middle cerebral artery bifurcation (1), distal anterior cerebral artery (1), basilar artery (1) and vertebral artery (1). The average neck size was 7.4 +/- 2.8 mm (3.5-12 mm), average width of the aneurysms was 10.6 +/- 5.7 mm (6.2-23 mm) and depth was 8.9 +/- 5.8 mm (3-22 mm). Three microcatheters (7 patients) and four microcatheters (1 patient) were introduced and used for coil delivery. Three or four coils were deployed and intermingled to stabilize the whole coil mass as well as to occupy the aneurysmal sac. When a relatively stable coil frame was formed, one coil was detached and subsequent coils were inserted. After the coil mass became more stable, other coils were also detached and all microcatheters were used for subsequent coil deployment. FINDINGS: All aneurysms were successfully treated without complications. Postemboilzation angiograms showed no contrast filling in 5 cases (100% occlusion) and a very small residual neck in 3 cases. There was no procedure related complication. CONCLUSION: The multiple microcatheter technique can be one technical option for the endovascular treatment of wide necked aneurysms.

Adult↗

PubMed2006

Clinical analysis of vertebrobasilar dissection.

BACKGROUND: The natural history of vertebrobasilar artery dissection (VAD) is not fully known. The purpose of this study was to review the clinical outcome of the patients with VAD, then to propose an appropriate management strategy for VAD. METHOD: From 1992 to 2004, 35 VAD patients admitted to our institutes were retrospectively reviewed. There were 28 men and 7 women, whose age ranged from 4 to 67 years with a mean age of 44 years. Angiography was assessed to document the shape, and location of the dissecting aneurysm with respect to the posterior inferior cerebellar artery (PICA). A modified Rankin score was assigned for functional outcome. The functional outcome scores were analyzed according to the patient's age, gender, hypertension history, the pattern of initial manifestation, angiographic shape of VAD, angiographic location of VAD, treatment modality. FINDINGS: There was no statistically significant difference between the functional outcome with age, gender, trauma history and past medical history of hypertension. Of 35 patients, 22 presented with SAH, 11 with ischemic symptoms and 2 were incidentally detected. The patients without SAH had a better functional outcome than those with SAH (p = 0.029). There was statistical significance between Hunt-Hess (H-H) grade and clinical outcome (p = 0.032). The shape and location of VAD was not significantly related to the functional outcome (p = 0.294, 0.840). But all the cases of rebleeding and mortality (except one case with initially poor H-H grade) developed exclusively in patients with aneurysms. There was no statistically significant correlation between the treatment modality and the outcome (p = 0.691). CONCLUSION: The VAD patients with SAH would be recommended to be managed by either surgical or endovascular treatment, but those without SAH, could be managed conservatively with antiplatelet therapy and/or anticoagulation.

Adolescent↗

PubMed2003

Hyperventilation-induced limb shaking TIA in Moyamoya disease.

The authors present a case of hyperventilation-induced left upper limb shaking from an underlying Moyamoya disease. Video EEG monitoring and SPECT study were performed. Leptomeningeal collateral circulation was investigated by conventional angiography and by SPECT study with acetazolamide. Limb shaking in Moyamoya disease may result from a transient hypoperfusion of the contralateral frontoparietal cortex rather than basal ganglia.

Acetazolamide↗

PubMed2003

Aplasia of the internal carotid artery.

BACKGROUND: The majority of previous reports on this rare agenesis of the internal carotid artery (ICA) have been limited to reporting upon its association with other congenital anomalies case by case. In order to collectively summarize this congenital anomaly of ICA, we have reviewed nine cases of ICA aplasia and their associated abnormalities. METHODS: Nine cases of ICA aplasia were reviewed. The diagnosis of aplasia or agenesis of the ICA was based on angiographic findings and the presence of an absent or hypoplastic bony carotid canal by temporal bone computed tomography (TBCT). Their presumable embryological aetiologies, initial presenting symptoms, unusual collateral circulations, as demonstrated by angiographies, and various associated anomalies are reviewed. FINDINGS: The initial presentations were; subarachnoid haemorrhage in three patients, headache in one patient and ischemic symptoms and signs in three patients. The remaining two cases were found incidentally during angiography for other diseases. Collateral circulations to the middle cerebral artery ipsilateral to the ICA aplasia were via posterior communicating artery (P-com) or anterior communicating artery (A-com). On TBCT, all cases but one demonstrated agenesis of the bony carotid canal and the remaining case showed a hypoplastic canal. Cerebral aneurysms were found in six patients, four with A-com aneurysm, one with a basilar bifurcation aneurysm, and one with both a right P-com and a left cavernous ICA aneurysm; two incidentally found cases had no aneurysm. Other associated abnormalities were found in four cases; one case of hypoplasia of the common carotid artery (CCA) with an arachnoid cyst at the temporal pole, one case of abnormal origin of the right CCA from the aorta and the right subclavian artery from the descending aorta, one case of congenital temporomandibular joint (TMJ) ankylosis, and one case of nasopharyngeal angiofibroma with atresia of the upper basilar artery. Except for the atresia of the upper basilar artery, all such abnormalities were found on the same side as the ICA aplasia. INTERPRETATION: Agenesis or aplasia of ICA may be entirely harmless. However, associated conditions such as cerebral aneurysm or abnormal collateral channels should alert clinicians to the possibility of deterioration to life-threatening conditions, such as subarachnoid haemorrhage or irreversible ischemia. Other associated anomalies are commonly depicted on the same side as the ICA aplasia and may also give rise to issues of clinical importance.

Adolescent↗

PubMed2003

Changes in vascular responses of the basilar artery to acetylcholine and endothelin-1 in an experimental rabbit vasospasm model.

BACKGROUND: This study aimed to clarify the characteristics of the basilar arteries of rabbits two and seven days after subarachnoid haemorrhage (SAH) and to investigate the influence of hypoxia on vascular responses to acetylcholine and endothelin-1. METHODS: Thirty four New Zealand white rabbits were divided into 3 groups: 1) control (n=6), 2) 2 days post SAH (n=15), and 3) 7 days post SAH (n=13). Rabbits in the groups 2 and 3 underwent vertebral angiography before sacrifice. Harvested vascular rings were suspended in a small vessel myograph system for isometric tension recording in response to vasodilatory and vasoconstrictory stimulation in oxygenated (95% O2/5% CO2) and hypoxic (95% N2/5% CO2) conditions. To investigate the response to a vasodilator, acetylcholine (ACh) (10(-7) to 3 x 10(-4) M) was applied to a basilar artery pre-contracted with histamine (10(-6) approximately 10(-5) M). To investigate the response to a vasoconstrictor, the effect of endothelin-1 (ET-1) (10(-11) to 3 x 10(-8) M) was observed in quiescent rings. FINDINGS: Seven of 15 rabbits that underwent angiography two days after operation showed vasospasm to 64.3+/-11.2% of the original diameter; likewise seven of the 13 rabbits studied seven days after operation showed vasospasm to 64.9+/-10.9% of the original diameter. Hypoxic conditions significantly reduced the relaxation response to ACh but did not influence basilar artery contraction to ET-1. Responses to ACh and ET-1 did not differ significantly in vessels from animals with or without vasospasm at 2 days. In contrast, at 7 days vascular responses to ACh and ET-1 were significantly less in vessels from animals with vasospasm than those without (p=0.029, 0.032), and also less than in vessels from animals with vasospasm at day 2 (p=0.002, 0.004). There was not a significant difference in the vascular responses of basilar arteries from animals without vasospasm. INTERPRETATION: The markedly lower vascular responses of basilar arteries of rabbits to ACh and ET-1 found seven days after SAH may relate to delayed vasospasm in patients with SAH.

Acetylcholine↗

PubMed2002

Radiosurgery of intracranial cavernous malformations.

BACKGROUND: The efficacy of radiosurgery in cases of surgically high risk symptomatic cavernous malformations (CMs) for reducing haemorrhagic risk and for seizure control has not been clearly documented and the radiation-induced complications of radiosurgery remain problematic. The authors present a retrospective clinical analysis of 22 cases of CMs treated by radiosurgery. METHODS: Twenty-two patients with symptomatic CMs were treated by linear accelerator (LINAC) radiosurgery or Gamma knife (GK) between 1995 and 1998. Medical records including radiological investigations were carefully reviewed to the last follow-up. The mean age of the patients was 34.1 years (12-56) and the male to female ratio was 12:10. Twenty patients reported at least one episode of bleeding and four had undergone microsurgery before radiosurgery. The remaining two patients presented with seizure without evidence of recent haemorrhage. In 16 cases, the CMs were deep-seated, and the others were located in the cerebral hemispheres; four were located at an eloquent area. LINAC radiosurgery using computed tomography scan was performed in 11 cases until May 1997, after which GK radiosurgery using magnetic resonance (MR) image was performed in 11 cases. The volume of the lesion ranged from 0.09 cc to 4.8 cc (mean 1.42 cc) and the mean marginal dose was 16.1 Gy (8-24). The median follow-up period after radiosurgery was 38.3 months (21-67). The rate of haemorrhage, seizure, and neurological deterioration following radiosurgery was analyzed, and the rate of haemorrhage was compared to that seen in natural course reports. FINDINGS: There was one case of haemorrhage during the follow-up period and the seizure was well controlled with anticonvulsants. In the group with prior haemorrhage, the bleeding rate of cavernous malformation after radiosurgery (1.55%/year) was lower than that of pre-radiosurgical period (35.5%/year, t=1.296, P=0.04). Six patients showed neurological deterioration following radiosurgery, however, the neurological deficits persisted in only two of the patients with LINAC. The radiosurgical modality (LINAC vs. GK) showed a possible correlation to radiation induced neurological deficits (P=0.06). On the MR images at the last follow-up, the lesion was decreased in eleven patients, increased in one, and no change was found in 10 cases. The T2 weighted MR images revealed a perilesional high signal change in nine patients. This signal change was not statistically related to lesion size (P=0.236), location (P=0.658), nor radiation dose (P=0.363), but was dependent on the treatment modality (P=0.02). New-enhancing lesion and a new cyst were each found in one case, respectively, during the follow-up. INTERPRETATION: Radiosurgery may be a good alternative option for treatment of surgically high risk CMs. However, the optimal radiosurgical technique, dose adjustment, and proper delineation of the mass are prerequisites. Radiosurgery induced complications are still problematic and post-radiosurgery MR image changes need to be further elucidated.

Adolescent↗

PubMed2001

Expression of interleukin-1 beta in lipopolysaccharide stimulated monocytes derived from patients with aneurysmal subarachnoid hemorrhage is correlated with cerebral vasospasm.

Cerebral arterial vasospasm is a frequent complication after aneurysmal subarachnoid hemorrhage (SAH). Immunological activation may affect the development of vasospasm. This study measured the cytokines released from lipopolysaccharide-stimulated monocytes of SAH patients. We measured cerebral artery diameters before and after surgery for SAH. The activation index of interleukin-1 beta (IL-1 beta), but not tumor necrosis factor-alpha (TNF-alpha), was higher in patients with symptomatic vasospasm (5.6+/-1.7; n=11) than in patients without (1.8+/-0.4; n=11) (P=0.039). Furthermore, the IL-1 beta activation index was correlated with the degree of the postoperative angiographic vasospasm (correlation coefficient=-0.66, P=0.007). Individual variation in systemic immune activation, measured by monocyte-derived IL-1 beta expression levels after stimulation, may be associated with the development of vasospasm after aneurysmal SAH.

Adult↗

PubMed2001

Development of glucose-induced insulin resistance in muscle requires protein synthesis.

Muscles and fat cells develop insulin resistance when exposed to high concentrations of glucose and insulin. We used an isolated muscle preparation incubated with high levels of glucose and insulin to further evaluate how glucose-induced insulin resistance (GIIR) is mediated. Incubation with 2 milliunits/ml insulin and 36 mm glucose for 5 h resulted in an approximately 50% decrease in insulin-stimulated muscle glucose transport. The decrease in insulin responsiveness of glucose transport induced by glucose was not due to impaired insulin signaling, as insulin-stimulated phosphatidylinositol 3-kinase activity and protein kinase B phosphorylation were not reduced. It has been hypothesized that entry of glucose into the hexosamine biosynthetic pathway with accumulation of UDP-N-acetylhexosamines (UDP-HexNAcs) mediates GIIR. However, inhibition of the rate-limiting enzyme GFAT (glutamine:fructose-6-phosphate amidotransferase) did not protect against GIIR despite a marked reduction of UDP-HexNAcs. The mRNA synthesis inhibitor actinomycin D and the protein synthesis inhibitor cycloheximide both completely protected against GIIR despite the massive increases in UDP-HexNAcs and glycogen that resulted from increased glucose entry. Activation of AMP-activated protein kinase also protected against GIIR. These results provide evidence that GIIR can occur in muscle without increased accumulation of hexosamine pathway end products, that neither high glycogen concentration nor impaired insulin signaling is responsible for GIIR, and that synthesis of a protein with a short half-life mediates GIIR. They also suggest that dephosphorylation of a transcription factor may be involved in the induction of GIIR.

Animals↗

PubMed2001

Radiation technology in the preparation of polyethylene oxide hydrophilic gels and immobilization of proteases for use in medical practice.

This paper deals with the development of a technology for making a hydrophilic gel of polyethylene oxide reception in which radiating ability is employed to cause cross-linking of polymers in a water solution. The gel of polyethylene oxide was shown to be non-toxic, contain 5-50% of polymer and be useful in composite medicinal forms along with biologically active substances including Bac. subtilis proteases. Proteases immobilized in the gel possess high thermal stability and proteolytic activity and are readily applied in medicine. The effect of immobilized proteolytic and glucolytic enzymes of Bac. subtillis (Immozimase) on the warm ischemia-reperfusion (I/R) which can cause hepatic and jejunum injury was also studied. These enzymes were immobilized on water-soluble polymer polyethylene glycol by means of an electron beam. The number of degranulated mast cells as well as serum ALT after I/R in the group with Immozimase was decreased to almost half as compared with the control group. Pretreatment with Immozimase resulted in significant reduction of hepatic and gut neutrophil accumulation as compared with control animals. It was concluded that Immozimase has a protective effect for hepatic and gut ischemia/reperfusion, and this effect seems to be associated with prevention of leukocyte accumulation.

Bacillus subtilis↗

PubMed2001

Prevalence of Gs alpha mutations in Korean patients with pituitary adenomas.

The reported frequencies of Gs alpha mutations (gsp mutations) in growth hormone (GH)-secreting pituitary adenomas are variable (ranging from 4.4 to 43%), and the presence of these mutations in the other pituitary adenomas is still a matter of controversy. Previous clinical and biochemical analyses of patients with GH-secreting pituitary adenomas and gsp mutations produced conflicting results and did not demonstrate obvious characteristics. Therefore, we investigated the prevalence of gsp mutations in Korean patients with pituitary adenomas and elucidated the characteristics of these patients. Forty-four GH-secreting adenomas, 7 prolactin (PRL)-secreting adenomas and 32 clinically non-functioning adenomas were examined for the presence of point mutations in codon 201 and 227 of the Gs alpha gene using a nested PCR and direct sequencing of DNA extracted from fresh tissue or paraffin-embedded pituitary adenoma samples. Seven of the 44 GH-secreting pituitary adenomas had point mutations at codon 201 or 227; of these, five mutations were in codon 201 and two were in codon 227. In patients with gsp mutations, mean tumor size was significantly smaller than in patients without gsp mutations (15.9+/-8.7 mm vs. 24.9+/-14.9 mm, P<0.05). Age, sex, basal GH levels, GH response to oral glucose loading, GH response to octreotide and surgical outcome were not different in the two groups. One of the 32 clinically non-functioning pituitary adenomas had a point mutation at codon 201; none of the seven prolactinomas had these mutations. These results show that gsp mutations are not rare in Korean acromegalic patients and mean tumor size is significantly smaller in acromegalic patients with gsp mutations. Our results also confirm the low frequency of gsp mutations in clinically non-functioning pituitary adenomas and the absence of gsp mutations in prolactinoma.

Acromegaly↗

PubMed2000

A co-operative study: clinical characteristics of 334 Korean patients with moyamoya disease treated at neurosurgical institutes (1976-1994). The Korean Society for Cerebrovascular Disease.

A co-operative study was conducted to determine the clinical characteristics of patients with moyamoya disease who were diagnosed and treated at neurosurgical institutes in Korea before 1995. Twenty-six hospitals contributed 505 cases and among them, the clinical characteristics of 334 patients with definite moyamoya disease were evaluated. The number of patients began to increase from the late 1980s, and after that approximately 20 patients were treated each year. There were two age peaks: from six to 15 and from 31 to 40 years of age. Haemorrhagic manifestations occurred in approximately 43% of the patients. The major clinical manifestations were haemorrhage in adults (62.4%) and ischaemia in children (61.2%). Overall 54.5% of the patients experienced decreased consciousness levels, mainly due to intracranial haemorrhage or cerebral infarction. In the patients with ischemic manifestations, the adult patients were more likely to have cerebral infarction than the pediatric patients (80% vs. 39%) and the pediatric patients were more likely to have TIA (61% vs. 25%). Thirty eight percent of the patients underwent bypass surgery and 53% of these procedures were performed bilaterally. Treatment policies, including indications for bypass surgery and commonly used drugs, were somewhat different according to the institution. Overall favorable outcome was 73%, and the most significant factor affecting poor outcome was haemorrhagic manifestation. This article describes the characteristics of 334 patients with moyamoya disease, who were diagnosed and treated at neurosurgical institutes in Korea before 1995.

Adolescent↗

PubMed2000

Skeletal muscle respiratory uncoupling prevents diet-induced obesity and insulin resistance in mice.

To determine whether uncoupling respiration from oxidative phosphorylation in skeletal muscle is a suitable treatment for obesity and type 2 diabetes, we generated transgenic mice expressing the mitochondrial uncoupling protein (Ucp) in skeletal muscle. Skeletal muscle oxygen consumption was 98% higher in Ucp-L mice (with low expression) and 246% higher in Ucp-H mice (with high expression) than in wild-type mice. Ucp mice fed a chow diet had the same food intake as wild-type mice, but weighed less and had lower levels of glucose and triglycerides and better glucose tolerance than did control mice. Ucp-L mice were resistant to obesity induced by two different high-fat diets. Ucp-L mice fed a high-fat diet had less adiposity, lower levels of glucose, insulin and cholesterol, and an increased metabolic rate at rest and with exercise. They were also more responsive to insulin, and had enhanced glucose transport in skeletal muscle in the setting of increased muscle triglyceride content. These data suggest that manipulating respiratory uncoupling in muscle is a viable treatment for obesity and its metabolic sequelae.

Animals↗

PubMed2000

Palliatively treated cerebral arteriovenous malformations: follow-up results.

The purpose of this study was to evaluate the benefits of palliative embolisation of patients with inoperable intracranial AVMs. It involved the analysis of the long-term clinical follow-up results of 27 patients with inoperable intracranial AVMs. Sixteen patients were treated medically and 11 patients received partial embolisation. The mean size of the lesions was 7.2 +/- 2.6 cm, and the mean follow-up period was 99 +/- 44 months (range 52-192 months). There were no significant statistical differences in the sex, age, size, venous drainage pattern, location of the lesions or presented symptoms. The analysis of the long-term clinical follow-up results showed no significant difference in either the risk of haemorrhage or clinical status of the patients in the two treatment groups. Of the 16 patients in the medical treatment group, 8 (50%) showed a clinical improvement, 3 no improvement and 5 (31%) deterioration. Of the 11 patients in the embolisation group, 5 (45.5%) showed clinical improvement, 3 no improvement and 3 (27.3%) deterioration (P = 0.871). Twenty-five percent (4 cases) of patients in the medical group and 45.5% (5 cases) of patients in the embolisation group suffered from haemorrhage during the follow-up period (P = 0.270). Complications related to embolisation occurred in three cases. This comparative study shows that palliative partial embolisation of intracranial AVMs, in all probability does not produce better clinical results than medical treatment.

Adult↗

PubMed2000

Mechanisms underlying impaired GLUT-4 translocation in glycogen-supercompensated muscles of exercised rats.

Exercise training induces an increase in GLUT-4 in muscle. We previously found that feeding rats a high-carbohydrate diet after exercise, with muscle glycogen supercompensation, results in a decrease in insulin responsiveness so severe that it masks the effect of a training-induced twofold increase in GLUT-4 on insulin-stimulated muscle glucose transport. One purpose of this study was to determine whether insulin signaling is impaired. Maximally insulin-stimulated phosphatidylinositol (PI) 3-kinase activity was not significantly reduced, whereas protein kinase B (PKB) phosphorylation was approximately 50% lower (P < 0.01) in muscles of chow-fed, than in those of fasted, exercise-trained rats. Our second purpose was to determine whether contraction-stimulated glucose transport is also impaired. The stimulation of glucose transport and the increase in cell surface GLUT-4 induced by contractions were both decreased by approximately 65% in glycogen-supercompensated muscles of trained rats. The contraction-stimulated increase in AMP kinase activity, which has been implicated in the activation of glucose transport by contractions, was approximately 80% lower in the muscles of the fed compared with the fasted rats 18 h after exercise. These results show that both the insulin- and contraction-stimulated pathways for muscle glucose transport activation are impaired in glycogen-supercompensated muscles and provide insight regarding possible mechanisms.

3-O-Methylglucose↗

PubMed2000

High-fat diet-induced muscle insulin resistance: relationship to visceral fat mass.

It has been variously hypothesized that the insulin resistance induced in rodents by a high-fat diet is due to increased visceral fat accumulation, to an increase in muscle triglyceride (TG) content, or to an effect of diet composition. In this study we used a number of interventions: fish oil, leptin, caloric restriction, and shorter duration of fat feeding, to try to disassociate an increase in visceral fat from muscle insulin resistance. Substituting fish oil (18% of calories) for corn oil in the high-fat diet partially protected against both the increase in visceral fat and muscle insulin resistance without affecting muscle TG content. Injections of leptin during the last 4 days of a 4-wk period on the high-fat diet partially reversed the increase in visceral fat and the muscle insulin resistance, while completely normalizing muscle TG. Restricting intake of the high-fat diet to 75% of ad libitum completely prevented the increase in visceral fat and muscle insulin resistance. Maximally insulin-stimulated glucose transport was negatively correlated with visceral fat mass (P < 0.001) in both the soleus and epitrochlearis muscles and with muscle TG concentration in the soleus (P < 0.05) but not in the epitrochlearis. Thus we were unable to dissociate the increase in visceral fat from muscle insulin resistance using a variety of approaches. These results support the hypothesis that an increase in visceral fat is associated with development of muscle insulin resistance.

Adipose Tissue↗

PubMed2000

Performance of respirator filters using quality factor in Korea.

A respirator filter of good quality has not only high aerosol collection efficiency but also low air resistance. "Quality factor", which is expressed with aerosol penetration and pressure drop, can be used to rank the performance of respirator filters within the same category. This study focuses on evaluating several respirator filters which are widely used in Korea using quality factor. Two mechanical filters and three filtering facepieces made by different manufacturers were measured aerosol penetrations and pressure drops by an automatic filter tester (CertiTest Model 8110, TSI Inc., St. Paul, USA) at four flow rates of 10, 32, 64 and 85 L/min. NaCl aerosols used were reported to be mean size of 0.1 microm and geometric standard deviation of <1.9. The penetrations and pressure drops of all filters have strong flow rate dependency. The filter quality factors decrease sharply as flow rates are increased. The mechanical filter S and filtering facepiece M are shown better filter quality than others in the same category. Since some certified filters are found to be inappropriate in the workplace exposed to fume, this result suggests that the current certified filter test protocol for respirators should be changed for the new protocol using smaller aerosols.

Aerosols↗

PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗

PubMed2000

Fit factors for quarter masks and facial size categories.

Respirator fit testing is necessary before entering hazardous working environments to ensure that the respirator, when worn, satisfies a minimum fit and that the wearer knows when the respirator fits properly. In the many countries that do not have fit testing or total inward leakage regulations (including Korea), however, many workers wearing respirators may be potentially exposed to hazardous environments. It is necessary to suggest a useful tool to provide an alternative for fit testing in these countries. This study was conducted to evaluate fitting performance for quarter-mask respirators, and fit factors in facial size categories based on face lengths and lip lengths of the wearers. A total of 778 subjects (408 males, 370 females) were fit tested for three quarter masks: Sejin Co. SK-6 (Ulsan, Korea), Yongsung Co. YS-2010 S (Seoul, Korea), and 3 M Co. Series 7500 Medium (MN, USA) masks with a PortaCount 8020 (TSI Co., USA). A facial dimension survey of the subjects was conducted to develop facial size categories, on the basis of face length and lip length. Geometric mean fit factors (GMFFs) of Series 7500 Medium were found to be the highest of the three respirators. All of the respirators were more suitable for males than females in fitting performance. The Series 7500 Medium fitted a large number of the males tested, since the GMFFs for males were above 100 for every box of facial size categories, and high pass proportion rates were shown at an individual fit factor level of 100. The YS-2010 S provides an adequate fit for males in a limited range of facial dimensions. The Series 7500 Medium is more limited in providing adequate fit for females at specific facial dimensions than for males. For adequate fitting performance, the SK-6 is not preferentially recommended for Korean male and female workers due to low GMFFs and pass proportions. The result of this study indicates that after more accurate studies are performed, facial size categories, on the basis of facial dimensions, could be a useful tool to assist in the selection of adequately fitting respirators for workers in the countries having no fit testing requirements.

Adult↗