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Biomedical subjects

R Westerman

Publications and source records attributed to R Westerman.

13 recordsLinked to original sources
PubMed2003

Transcriptome analysis of the cowpea weevil bruchid: identification of putative proteinases and alpha-amylases associated with food breakdown.

We describe here the first systematic work to discover insect genes involved in food breakdown using a cDNA library enriched for gut-expressed transcripts from Callosobruchus maculatus. A total of 1056 clones were screened for cDNA insert-containing plasmids, and 503 nonredundant open reading frames were discovered. Twenty-three inferred genes potentially involved in digestive processes in cowpea weevil were identified, including proteinases and amylases. The predicted catalytic sites were identified in the inferred cysteine and aspartic acid proteinases, and in alpha-amylases. Transcriptome analysis of the cowpea bruchid will potentially permit gene discovery in other beetles, an insect order of major economic and ecological importance that is poorly represented in genomic databases.

Amino Acid Sequence↗
PubMed2003

Neurological effects of radiofrequency radiation.

BACKGROUND: The health effects of radiofrequency radiation (RFR) and the adequacy of the safety standards are a subject of debate. One source of human data is case reports regarding peripheral neurological effects of RFR, mainly noxious sensations or dysaesthesiae. AIM: To investigate health effects, neurophysiological mechanisms and safety levels for RFR. METHODS: We conducted a literature search for case reports and case series associated with mobile phone technology as well as other RFR sources using specific search terms on PubMed. RESULTS: We identified 11 original articles detailing case reports or case series and matching the search criteria. Five of the identified papers were written by at least one of the authors (B.H. or R.W.). CONCLUSIONS: Cases have arisen after exposure to much of the radiofrequency range. In some cases, symptoms are transitory but lasting in others. After very high exposures, nerves may be grossly injured. After lower exposures, which may result in dysaesthesia, ordinary nerve conduction studies find no abnormality but current perception threshold studies have found abnormalities. Only a small proportion of similarly exposed people develop symptoms. The role of modulations needs clarification. Some of these observations are not consistent with the prevailing hypothesis that all health effects of RFR arise from thermal mechanisms.

Cell Phone↗
PubMed2002

Neurological changes induced by a mobile phone.

Dysaesthesiae of the scalp after mobile phone use have been previously reported, but the basis for this has not been clear. We report a case of a 34-year-old journalist who complained of symptoms associated with use of a mobile phone. She agreed to a provocation study with her phone. Current perception threshold testing before and after exposure showed marked changes in the C-fibre nerves of the affected area compared with the opposite side. The case is supportive of a neurological basis for some cases of dysaesthesiae associated with mobile phone use.

Adult↗
PubMed2001

Neurological abnormalities associated with CDMA exposure.

Dysaesthesiae of the scalp and neurological abnormality after mobile phone use have been reported previously, but the roles of the phone per se or the radiations in causing these findings have been questioned. We report finding a neurological abnormality in a patient after accidental exposure of the left side of the face to mobile phone radiation [code division multiple access (CDMA)] from a down-powered mobile phone base station antenna. He had headaches, unilateral left blurred vision and pupil constriction, unilateral altered sensation on the forehead, and abnormalities of current perception thresholds on testing the left trigeminal ophthalmic nerve. His nerve function recovered during 6 months follow-up. His exposure was 0.015-0.06 mW/cm(2) over 1-2 h. The implications regarding health effects of radiofrequency radiation are discussed.

Adult↗
PubMed2000

Neurological abnormalities associated with mobile phone use.

Dysaesthesiae of the scalp after mobile phone use have been previously reported but the pathological basis of these symptoms has been unclear. We report finding a neurological abnormality in a patient after prolonged use of a mobile phone. He had permanent unilateral dysaesthesiae of the scalp, slight loss of sensation, and abnormalities on current perception threshold testing of cervical and trigeminal nerves. A neurologist found no other disease. The implications regarding health effects of mobile phones and radio-frequency radiation is discussed.

Aged↗
PubMed1999

Radiofrequency electrocution (196 MHz).

Radiofrequency (RF) electrocutions are uncommon. A case of electrocution at 196 MHz is presented partly because there are no previous reports with frequencies as high as this, and partly to assist in safety standard setting. A 53-year-old technician received two brief exposures to both hands of 2A current at 196 MHz. He did not experience shock or burn. Progressively over the next days and months he developed joint pains in the hands, wrists and elbows, altered temperature and touch sensation and parasthesiae. Extensive investigation found no frank neurological abnormality, but there were changes in temperature perception in the palms and a difference in temperature between hands. His symptoms were partly alleviated with ultra-sound therapy, phenoxybenzamine and glyceryl trinitrate patches locally applied, but after several months he continues to have some symptoms. The biophysics and clinical aspects are discussed. It is postulated that there was mainly surface flow of current and the micro-vasculature was effected. Differences to 50 Hz electrocution are noted. Electrocution at 196 MHz, even in the absence of burns may cause long-term morbidity to which physicians should be alerted. Safety standards should consider protection from electrocution at these frequencies.

Arthralgia↗
PubMed1992

Simultaneous measurements of cardiac noradrenaline spillover and sympathetic outflow to skeletal muscle in humans.

1. Muscle sympathetic nerve activity (MSA) was recorded in the peroneal nerve at the knee by microneurography in ten healthy subjects and determinations were made simultaneously of intra-arterial blood pressure, and whole-body and cardiac noradrenaline spillover to plasma. Measurements were made at rest, during isometric handgrip at 30% of maximum power and during stress induced by forced mental arithmetic. 2. At rest there were significant positive correlations between spontaneous MSA (expressed as number of sympathetic bursts min-1) and both spillover of noradrenaline from the heart and concentration of noradrenaline in coronary sinus venous plasma. 3. Both isometric handgrip and mental arithmetic led to sustained increases of blood pressure, heart rate and MSA. Plasma concentrations of noradrenaline and spillover of noradrenaline (total body and cardiac) increased. In general the effects were more pronounced during handgrip than during stress. 4. When comparing effects during handgrip and stress the ratio between the fractional increases of MSA and cardiac noradrenaline spillover were significantly greater during handgrip. 5. The data suggest (a) that there are proportional interindividual differences in the strength of resting sympathetic activity to heart and skeletal muscle which are determined by a common mechanism and (b) that handgrip and mental stress are associated with differences in balance between sympathetic outflows to heart and skeletal muscle.

Adult↗
PubMed1991

Effects of desipramine on sympathetic nerve firing and norepinephrine spillover to plasma in humans.

In isolated organs, or when given in low dose intra-arterially, tricyclic antidepressant drugs are known to block reuptake of norepinephrine into sympathetic nerve varicosities, with a resultant increased norepinephrine washout. On the other hand, systemic administration of such drugs in humans reduces norepinephrine spillover to plasma. To clarify these seemingly contradictory findings, we have measured concurrently muscle sympathetic activity in the peroneal nerve (microneurography) and rates of norepinephrine spillover to plasma for the body as a whole and for the heart, the kidneys, and the forearm (radiotracer technique), both before and after intravenous infusion of desipramine, 0.5 mg/kg. Desipramine lowered the overflow of norepinephrine to plasma for the body as a whole and from the forearm and the kidneys (by 30-50%) but increased cardiac norepinephrine spillover by 25%. Both the number of sympathetic bursts per min in the peroneal nerve and their mean voltage amplitudes were markedly reduced after desipramine; total activity (bursts/min x mean burst amplitude) fell by approximately 90%. The effects of desipramine on norepinephrine spillover are explicable in terms of inhibition of central sympathetic outflow, balanced against the local blockade of transmitter reuptake. In most sites, the predominant effect is a reduction of norepinephrine overflow. For the heart, where reuptake is so important in transmitter disposition, the net effect is increased overflow.

Adult↗
PubMed1988

Non-invasive tests of neurovascular function: reduced axon reflex responses in diabetes mellitus of man and streptozotocin-induced diabetes of the rat.

The prevalence of neuropathy and microangiopathy complicating diabetes mellitus led to our development of non-invasive tests of neurovascular function. On the foot dorsum of consenting normal subjects, diabetic patients, normal and streptozotocin-induced (STZ) diabetic rats, transcutaneous electrical nerve stimulation (TENS) with 1, 2, 4, 8, 16 pulses at 150 V, 0.75 ms, at 2 Hz, evokes transient cutaneous axon reflex vasodilatation measured by a laser Doppler (Periflux Pfld). This tests the integrity of both the polymodal nociceptor/primary afferent nerves and microvessels in the skin. TENS-evoked axon reflexes are reduced in diabetics (particularly with neuropathy) and progressively in rats 40-100 days after STZ administration. This could be reversed in rats by a single injection of 3 units of soluble insulin at 100 days post STZ. The microvascular endothelium and smooth muscle are tested in man by measuring vasodilatation induced by iontophoretic application of 2 mC acetylcholine (ACh) and 4 mC sodium nitroprusside (NaNP), respectively. Diabetics show reduced ACh-evoked endothelium-dependent vasodilator responses, but the direct smooth muscle (endothelium-independent) responses evoked by NaNP are not reduced. Such functional neurovascular disturbances probably underlie many complications of diabetes mellitus, and the potential for these to be reversible with appropriate therapy can now be examined with such neurovascular tests.

Animals↗
PubMedDate not supplied

Bilateral infective endocarditis.

Two patients presenting with simultaneous right- and left-sided infective endocarditis requiring surgical intervention are reported. One patient developed aortic and pulmonic valve endocarditis following dental extraction, while the second patient developed mitral and tricuspid valve endocarditis secondary to a large body burn. The bilateral semilunar valve endocarditis was treated by porcine aortic valve replacement and debridement of the pulmonic valve. The bilateral atrioventricular valve endocarditis was treated by mitral and tricuspid valve replacement with porcine valves. The frequency and clinical settings in which this condition is likely to present are discussed.

Adolescent↗