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Biomedical subjects

M E Klein

Publications and source records attributed to M E Klein.

17 recordsLinked to original sources
PubMed2003

Microsecond pulsed optical parametric oscillator pumped by a Q-switched fiber laser.

We report on what is to our knowledge the first optical parametric oscillator (OPO) pumped by microsecond pulses from a wavelength-tunable solid-state laser. The singly resonant OPO (SRO) is based on a periodically poled LiNbO3 crystal and pumped with 2.1-micros-long pulses from an actively Q-switched Yb fiber laser. At an average fiber laser power of 3.6 W, the SRO generates 1.9-micros-long pulses with a repetition rate of 25 kHz and an average power of 560 mW at 3360 nm. The SRO was tuned from 1518 to 1634 nm (signal) and from 3145 to 3689 nm (idler) via the crystal temperature and poling period. By all-electronic tuning of the fiber laser wavelength over 19 nm, tuning of the mid-infrared idler wavelength over 195 nm was achieved.

Journal Article↗
PubMed2003

Rapidly tunable continuous-wave optical parametric oscillator pumped by a fiber laser.

We report on rapid, all-electronically controlled wavelength tuning of a continuous-wave (cw) optical parametric oscillator (OPO) pumped by an ytterbium fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled lithium niobate crystal in a four-mirror ring cavity. By tuning of the fiber-laser wavelength over 33 nm through an intracavity acousto-optic tunable filter, the OPO idler wavelength is tuned from 3160 to 3500 nm in 330 micros, corresponding to an idler frequency-tuning speed of 28 THz/ms. At a fiber-laser power of 6.6 W at 1074 nm, the singly resonant OPO generates 1.13-W cw idler radiation at 3200 nm.

Journal Article↗
PubMed2001

Fertility treatment in the forty and older woman.

PURPOSE: To determine the outcomes and logical progression of fertility treatment in women forty years and older using their own oocytes. METHODS: This was a retrospective study in which 401 completed treatment cycles in 152 women aged forty and older were reviewed. RESULTS: Assisted reproductive technology (ART) cycles (n = 58) were reviewed, comprising both in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT). Intrauterine insemination (IUI) cycles (n = 343) were reviewed, consisting of 38 unstimulated natural cycle-IUI (NC-IUI), 194 clomiphene citrate-IUI (CC-IUI), and 111 injectable gonadotropins-IUI (INJ-IUI) cycles. The live birth rate of 15.5% for ART cycles was significantly higher than the live birth rate of 3.2% seen for all IUI cycles (p = 0.0007). There were no differences among treatment groups in spontaneous abortion, preterm delivery, or ectopic pregnancy rates. CONCLUSIONS: For women > or = 40 years of age who wish to use their own eggs, ART offers the best chances for conception and delivery.

Adult↗
PubMed2000

EGO-1 is related to RNA-directed RNA polymerase and functions in germ-line development and RNA interference in C. elegans.

BACKGROUND: Cell-fate determination requires that cells choose between alternative developmental pathways. For example, germ cells in the nematode worm Caenorhabditis elegans choose between mitotic and meiotic division, and between oogenesis and spermatogenesis. Germ-line mitosis depends on a somatic signal that is mediated by a Notch-type signaling pathway. The ego-1 gene was originally identified on the basis of genetic interactions with the receptor in this pathway and was also shown to be required for oogenesis. Here, we provide more insight into the role of ego-1 in germ-line development. RESULTS: We have determined the ego-1 gene structure and the molecular basis of ego-1 alleles. Putative ego-1 null mutants had multiple, previously unreported defects in germ-line development. The ego-1 transcript was found predominantly in the germ line. The predicted EGO-1 protein was found to be related to the tomato RNA-directed RNA polymerase (RdRP) and to Neurospora crassa QDE-1, two proteins implicated in post-transcriptional gene silencing (PTGS). For a number of germ-line-expressed genes, ego-1 mutants were resistant to a form of PTGS called RNA interference. CONCLUSIONS: The ego-1 gene is the first example of a gene encoding an RdRP-related protein with an essential developmental function. The ego-1 gene is also required for a robust response to RNA interference by certain genes. Hence, a protein required for germ-line development in C. elegans may be a component of the RNA interference/PTGS machinery.

Amino Acid Sequence↗
PubMed1996

trans-2-phenylcyclopropylamine is a substrate for and inactivator of horseradish peroxidase.

Horseradish peroxidase (HRP) is well known for mediating the electron-transfer oxidation of electron-rich aromatic 'donors' such as phenols and anilines, but has not been described to oxidize aliphatic amines. We here confirm the inability of HRP to oxidize typical aliphatic amines, even those which would exist significantly as free bases at the operative pH. In contrast, trans-2-phenylcyclopropylamine (2-PCPA) is both a substrate (turnover product is cinnamaldehyde) and a time-dependent inactivator of HRP. These activities of 2-PCPA are consistent with either a concerted or rapid sequential one-electron-oxidation/ring-opening to give an intermediate capable of covalent binding to the enzyme. 2-PCPA is the first known example of a simple aliphatic amine which serves as a substrate for HRP under turnover conditions.

Amines↗
PubMed1995

Haemoprotein-mediated metabolism of enamines and the possible involvement of one-electron oxidations.

1. Microsomal metabolism of 1-benzylpiperidine (1-BP), its cis-2,6-dimethyl (cis-2,6-DMBP), 4,4-dimethyl (4,4-DMBP), and alpha, alpha-dimethyl (alpha, alpha-DMBP) analogues, and phencyclidine (PCP) has been studied to assess the involvement of P450 oxidation of the enamine tautomers of the initial endocyclic iminium metabolites. 2. The selective prevention by cyanide of the metabolite production of 1-benzyl-3-piperidone but not 1-benzyl-3-piperidinol from 1-BP is consistent with the enamine as the source of the 3-one metabolite. 3. The parent amines and particularly the independently prepared iminium species induced a pattern of metabolism-dependent irreversible inactivation of P450 benz-phetamine demethylase activity, consistent with involvement of enamine C-3 oxidation in the inactivation process. 4. Substrate activity of the endocyclic enamines and alpha-aminoketones (presumably the enol-enamine tautomers) for horseradish peroxidase under conditions where simple aliphatic amines display no activity is consistent with metabolic one-electron oxidations of the enamines.

Amines↗
PubMed1990

Transcutaneous bilirubinometer: intermeter reliability.

This study examined intermeter reliability on two transcutaneous bilirubinometers on 30 white prephototherapy infants between 36 and 42 weeks' gestation with birthweights greater than 2500 g. All infants were screened with both meters, on the forehead, within a 5-minute period. Meter readings were taken within 30 minutes following infant heelstick for serum bilirubin. The Pearson correlations between serum bilirubin and jaundice meter measurements were .75 for meter 1 and .76 for meter 2. The correlation between jaundice meter indices from the two meters was .87, leaving 13% of the variance in one meter not accounted for by the correlation with the other meter. An examination of the differences between the two meters revealed that in the upper range (greater than or equal to 16) meter 1 was always higher than meter 2 by, on the average, 2.6 points (SD = 1.3). In readings of 15 or less, the differences between the meters were inconsistent. Additionally, in 16 of 30 cases, the action levels from the two meters led to the same conclusion; in the remaining 14 cases, meter 1 gave a positive reading (indicating the need to determine serum bilirubin) while meter 2 gave an equivocal reading (indicating user discretion in deciding whether serum bilirubin should be determined). These data indicate that each meter should be individually evaluated to determine action indices, and that jaundice meters should not be used interchangeably on the same infant.

Bilirubin↗
PubMed1986

[Hemorrhagic internal pachymeningitis. A clinical study of 131 cases].

Between 1980 and 1985, 131 patients suffering from haemorrhagic internal pachymeningitis had undergone surgery. Mean patient age was 59 years (range: 16-90 years). Operation technique was burr-hole craniotomy with closed-system drainage in 124 cases. In five cases primary, in 24 cases secondary removal of the capsule was performed. An Ommaya reservoir was implanted in eight cases. All patients were re-examined after an average of six months and classified into six groups according to the neurological findings. Comparison of initial findings and final results showed an improvement in the patients' condition in 83 cases (63%). There was no change in 20 patients (15%) and deterioration in seven (5%). Twenty-one patients (16%) died during the observation period.

Adolescent↗
PubMed1984

An analysis of bowel perforation in patients with intussusception.

A barium colon examination is recommended for the diagnosis and reduction of intussusception in children, except when bowel perforation is evident either radiographically or clinically. In our experience and contrary to recent reports neither radiographic evidence of bowel obstruction nor an age of less than six months is a contraindication. We reviewed 40 patients diagnosed as having had intussusception and found five children aged more than six months with perforations discovered at operation. Three of the five children had plain radiographic findings of small bowel obstruction as did nine other children. In four of the 12 children with evidence of small bowel obstruction a successful hydrostatic reduction of the intussusception was carried out. Barium studies were performed for diagnosis and therapy in eight children with ileo-colic intussusception aged six months or less, four of whom had evidence of small bowel obstruction. In five, including two with obstruction, reduction of the intussusception was successful. The major contraindication to barium examination is radiographic or clinical evidence of perforation.

Adolescent↗
PubMed1981

Cyclophosphamide and dimethylsulfoxide in the treatment of squamous carcinoma of the lung. Therapeutic efficacy, toxicity, and pharmacokinetics.

To determine whether dimethylsulfoxide (DMSO) can potentiate antitumor activity of cyclophosphamide (CYC) in patients with squamous cell carcinoma of the lung, 14 patients were treated with 5 l of a 5% or 6% DMSO solution PO over 3 days and 1,500 mg CYC/m2 IV as a 60-min infusion on the third day of treatment. Serial blood, CSF, and urine samples were collected to assess the pharmacokinetics of CYC. Courses were repeated every 3-4 weeks. No antitumor responses were observed. Toxicity was mainly hematologic and similar to that of CYC alone. There was one death from infection during granulocytopenia. Nonhematologic toxicity was moderate to severe and included nausea (14 patients) and vomiting (five patients). The plasma pharmacokinetics of CYC in this study are similar to previously reported results for CYC alone, but the 24-h urinary excretion of CYC in our study is much lower than previously reported. Further studies in tumors more responsive to CYC may be warranted.

Adult↗
PubMed1978

Carcinoma of the lung and cigarette smoking. Effect on serum ribonuclease activity.

Serum ribonuclease levels were determined in 54 patients with lung carcinoma, 74 long-term cigarette smokers, and 172 nonsmokers. The mean serum ribonuclease level was significantly higher in patients with lung carcinoma and long-term smokers compared with healthy nonsmokers (P less than .001). The serum ribonuclease activity level was not related to chronological age, sex, or race of the smoker or nonsmoker population. Forty (75%) of 53 patients with lung cancer and 49 (66%) of 74 smokers had elevated serum ribonuclease levels compared with 13 (7%) of 179 nonsmoker healthy controls (P less than .001). The highest incidence of elevation was noted in patients with epidermoid carcinoma (95%).

Adenocarcinoma↗
PubMedDate not supplied

Incidence and pattern of jaundice in healthy breast-fed infants during the first month of life.

The incidence and pattern of jaundice in 155 normal, full-term, breast-fed, white infants was examined. Infants were screened for jaundice on Days 2, 3, 5, 7, 9, 11, and 13 following birth using transcutaneous bilirubinometry (TcB). By Day 3, 49.7% of the infants were classified as jaundiced (> 10 mg/dl). Infants with low TcB indices on Days 2, 3, and 5 never developed jaundice as indicated by elevated TcB indices on Days 7, 9, 11, and 13. Hence, it may be possible to target infants at risk for severe jaundice prior to discharge. The observed rate of 10.3% for breast-milk jaundice (jaundice present at Day 13) is significantly higher than the highest reported rate of 2.4% (z = 6.43, p < .01). Furthermore, the pattern of jaundice in these infants does not appear to have two peaks, indicating that it is not possible to distinguish between exaggerated physiologic jaundice and breast-milk jaundice using TcB.

Adult↗