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Biomedical subjects

H J Robertson

Publications and source records attributed to H J Robertson.

At least 19 recordsLinked to original sources
PubMed2001

Determination of enterostatin in human cerebrospinal fluid by capillary electrophoresis with laser induced fluorescence detection.

A capillary electrophoresis (CE) method with laser induced fluorescence (LIF) detection is described for quantification of enterostatin (Val-Pro-Asp-Pro-Arg), a pentapeptide involved in appetite regulation and insulin secretion. Enterostatin and two other pentapeptides belonging to the enterostatin family (i.e. Ala-Pro-Gly-Pro-Arg and Val-Pro-Gly-Pro-Arg) were well separated from each other. The peptides were fluorescently tagged with naphthalene-2,3- dicarboxaldehyde (NDA) and separated by micellar electrokinetic chromatography (MEKC) in the presence of methanol as an organic modifier. Coupled with LIF detection, the method had a detection limit of 4.8 x 10(-6) M for enterostatin. The relative standard deviation was to be 4.0% from five determinations of enterostatin at 37.2 microM in a human cerebrospinal fluid (CSF) sample. Twenty-three human CSF samples were analyzed. The level of enterostatin ranged from 24 microM to 51 microM with a mean (+/- SEM) value of 41.7 +/- 2.0 microM.

Amino Acid Sequence↗
PubMed2000

Acute optic neuropathy and transverse myelopathy in patients with antiphospholipid antibody syndrome: favorable outcome after treatment with anticoagulants and glucocorticoids.

We describe two patients with established antiphospholipid syndrome, who during periods of subtherapeutic anticoagulation, developed acute optic neuropathy and transverse myelopathy. Treatment with optimal anticoagulation and high dose glucocorticoids was followed by resolution of the neurologic deficits.

Acute Disease↗
PubMed1998

Distribution and characterization of enterostatin-like immunoreactivity in human cerebrospinal fluid.

Enterostatins belong to a family of peptides (e.g., Val-Pro-Asp-Pro-Arg, VPDPR; Ala-Pro-Gly-Pro-Arg, APGPR; and Val-Pro-Gly-Pro-Arg, VPGPR) derived from the tryptic cleavage of amino-terminal pentapeptide from procolipase. Pharmacologic studies have suggested a role for these peptides in appetite regulation and insulin secretion. Studies into the distribution of enterostatins or the role of endogenous peptides have not been possible until now due to the lack of a suitable method for assay. Using two polyclonal antibodies raised against VPDPR and APGPR and different chromatographic methods, we have examined the nature and distribution of enterostatin-like immunoreactivity in human cerebrospinal fluid. The results reported here show for the first time the presence of enterostatin-like immunoreactivity in the human cerebrospinal fluid. Further characterization of cerebrospinal fluid enterostatin-like immunoreactivity revealed that it is not due to APGPR, VPGPR, or VPDPR but to another peptide similar to VPDPR.

Adult↗
PubMed1991

Increased cerebrospinal fluid cyclo(His-Pro) content in schizophrenia.

Cyclo(His-Pro) (CHP) is a peptide endogenous to human brain and cerebrospinal fluid (CSF). In animal studies administration of exogenous CHP augments dopaminergic neurotransmission. To explore the role of this peptide in schizophrenia, a disease characterized by a hyperdopaminergic state, we have measured CSF CHP levels in control, never-medicated schizophrenics and medicated schizophrenics. Our data show a 53% increase in CSF levels of CHP in never-medicated schizophrenics (p = 0.015), and a 25% increase in medicated schizophrenics when compared to controls. We speculate that CHP may contribute to the expression of hyperdopaminergic symptoms in schizophrenia.

Adult↗
PubMed1990

Cervical myelography: survey of modes of practice and major complications.

A total of 68 major complications of cervical myelography were reported by 220 neuroradiologists in a mail survey. Two-thirds of the complications were attributed to cervical spine hyperextension and one-third to lateral C1-2 puncture. Narrow sagittal diameter of the spinal canal and severe cervical spondylosis were frequent contributing factors to hyperextension injury of the cervical spinal cord. Clinical and radiographic premyelography screening is suggested, with magnetic resonance imaging performed first in patients with spinal canal stenosis, severe spondylosis, and/or myelopathy of any cause. Neck extension should be minimal during myelography. All C1-2 punctures should be monitored with lateral fluoroscopy for accurate needle positioning and prevention of contrast medium injection into the spinal cord.

Cervical Vertebrae↗
PubMed1988

Occult carotid artery injury related to automobile seat belts.

A 24-year-old woman had a clinically occult injury of the carotid artery from the shoulder seat belt restraint in a motor vehicle accident. Acute thromboembolism and hemiplegia occurred two hours after her admission to the emergency department. There were contusions of the neck and chest (seat belt sign) but no associated injuries of the cervical spine, mandible, larynx, or brachial plexus. The diagnosis was made by carotid arteriography after the occurrence of thromboembolism. Early clinical suspicion, diagnosis, and surgical repair of the artery are necessary to prevent delayed or recurrent thromboembolism and stroke. Carotid artery and duodenal injuries in this patient were related to improperly fitting seat belts. The current useful preventive measures are adjustment of seat belts to individual body habitus and the regular use of snugly adjusted belts.

Adult↗
PubMed1988

Nonionic contrast media in radiology. Procedural considerations.

Reports of thrombus formation or embolism during angiography with nonionic contrast media were reviewed. Several factors were identified that may contribute to blood clot formation within or on the surface of angiographic catheters. Nonionic contrast media have a mild anticoagulant effect in vitro and in vivo. Careful and correct angiographic techniques are necessary to effectively use the nonionic contrast substances. As a basic principle, blood should not be mixed with the contrast agent prior to intravascular injection. Frequent flushing of the angiographic catheter with heparinized saline is recommended.

Angiography↗
PubMed1987

Thyrotropin-releasing hormone and cyclo (His-Pro)-like immunoreactivities in the cerebrospinal fluids of 'normal' infants and adults, and patients with various neuropsychiatric and neurologic disorders.

Levels of thyrotropin-releasing hormone (TRH) - and cyclo(His-Pro) (CHP)-like immunoreactivities and the activity of enzyme Pyroglutamate aminopeptidase (PAPase) were measured in cerebrospinal fluid (CSF) of over 100 normal adults (NA) and infants, and adult patients with various neurologic and neuropsychiatric disorders (NNDA). Levels of TRH and CHP in CSF of over 70% of the NA group were below 50 and 500 pg/ml respectively. The TRH- and CHP-like immunoreactivities in the remainder of the 30% of NA specimens exhibiting higher peptide concentrations were enzymatically and chromatographically characterized and were found to behave like authentic peptides. The levels of both of these peptides were significantly elevated in the CSF of most of the NNDA patients. An elevation in the CSF level of CHP was significantly correlated with the level of TRH, but not PAPase. Results from this study suggest that CSF elevation of TRH level may be due to a nonspecific response to stress that may be associated with hospitalization, myelogram procedure, and/or the neurologic and neuropsychiatric diseases for which the patients were admitted.

Adult↗
PubMed1987

Is all cyclo(His-Pro) derived from thyrotropin-releasing hormone?

Cyclo(His-Pro), or histidyl-proline diketopiperazine, is an endogenous cyclic dipeptide that is ubiquitously distributed in tissues and body fluids of both man and animals. This cyclic dipeptide is not only structurally related to thyrotropin-releasing hormone (TRH, pGlu-His-ProNH2), but it can also arise from TRH by the action of the enzyme pyroglutamate amino-peptidase (pGlu-peptidase). The data on the distribution of TRH, cyclo(His-Pro), and pGlu-peptidase under normal and abnormal conditions are summarized and potential relationships analyzed. We conclude that all of the cyclo(His-Pro) cannot be derived from TRH. Two additional sources of cyclo(His-Pro) are suggested. It is proposed that 29,247 molecular weight TRH prohormone, prepro TRH, which contains 5 copies of TRH sequence, can be processed to yield cyclo(His-Pro). Thus, both TRH and cyclo(His-Pro) share a common precursor, prepro[TRH/Cyclo(His-Pro)].

Animals↗
PubMed1987

Pyroglutamate aminopeptidase activity in human cerebrospinal fluid decreases with age.

The activity of pyroglutamate aminopeptidase, the major enzyme catalyzing thyrotropin-releasing hormone (TRH) metabolism in human CSF, decreased with age. This decrement is not due to age-dependent appearance of any enzyme inhibitor in CSF. The results of these studies underline the importance of using age-matched controls in assessing abnormalities of TRH metabolism in CSF during disease states.

Adult↗
PubMed1987

Blood clot formation in angiographic syringes containing nonionic contrast media.

Spontaneous thrombus formation may occur if blood is allowed to mix with a nonionic contrast medium in the injection syringe or angiographic catheter. This is probably due to the absence of significant inhibition of the normal blood coagulation mechanism by currently used nonionic contrast media. Careful angiographic techniques will prevent blood from mixing with the contrast medium before injection. The use of a three-way stopcock and connecting tube between catheter and syringe is suggested. Contrast material should be flushed from the catheter immediately after injection. Systemic anticoagulation is not justified as a means of preventing thrombus formation. The potential prophylactic use of heparin added to the contrast medium during angiography or premedication with aspirin, and the attendant risks of these techniques, are discussed.

Angiography↗
PubMed1984

Neuroimaging of the spine.

This article addresses the subject of available technology and techniques of neuroimaging of the spine. It also reviews broad areas of neuropathology such as congenital anomalies, degenerative joint disease, the postoperative spine, disorders of the spinal cord, neoplasia, trauma, and infection. A general approach to the radiographic diagnosis of spinal disorders is covered.

Humans↗
PubMed1983

Cerebellar lesion in myoclonic encephalopathy of infants.

The syndrome of opsoclonus and polymyoclonus developed in an infant who had acute meningoencephalitis with ataxia. A low-density cerebellar lesion was noted by computed tomography, subsequently resolving with residual cerebellar atrophy. The infant recovered completely, except for a mild intention tremor. This was the first documentation, to our knowledge, of an acute cerebellar lesion in this syndrome.

Cerebellar Ataxia↗