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A re-evaluation of biochemistry in medical school curricula is presented, with reference to designing more effective courses. Responses to a survey conducted among 103 medical students enrolled in two general biochemistry courses indicated that basic biochemistry would be considered more relevant to the medical curriculum if clinical applications were emphasized over basic principles. A majority of students (91%) expressed interest in applying biochemical principles to pathological conditions. They recommended that the biochemistry curriculum should include lectures on the significance of biochemistry in medical practice and its role in the life processes, laboratory comparisons of normal and pathological specimens, and course titles that reflect a more clinical orientation.
A report on the progress of the M.Sc. courses in clinical biochemistry run at the University of Surrey over the past 7 years is given. The previous experience and qualifications of the students and their careers subsequent to taking the course are analysed. A description of the course structure and syllabus is given. It is concluded that the course has been useful in attracting both science graduates and medical graduates of high calibre, in providing them with a sound laboratory-based training in clinical biochemistry, and in stimulating their interest in following a career in clinical biochemistry and chemical pathology.
The amount of laboratory time devoted to anatomy, biochemistry, and physiology has decreased substantially while lecture time has remained essentially unchanged. Most laboratories consist of student conduction of assigned exercises with a sprinkling of demonstrations, conferences, and seminars. Various objectives for laboratory programs are discussed. A great percentage of the student's final anatomy grade (approximately 40%) still depends on his laboratory performance, while in biochemistry and physiology, lab work contributes only 12% and 10%, respectively, toward his final grade. There is great reluctance to abandon the laboratory program, however, because of the significant role it is thought to play in medical education.
Plasma biochemistry often presents significant limitations in diagnosing borderline metabolic disorders, particularly within complex neurodevelopmental phenotypes. Here, we present the clinical genomic evaluation of a six-year patient presenting with early-onset hypotonia and severe gastrointestinal complications whose newborn screening panel did not evaluate biotinidase (BTD) activity. While initial baseline plasma biochemistry yielded borderline residual BTD function (46% of the population mean), targeted sequencing identified a novel, compound heterozygous hypomorphic variant (p.Thr459Met) in trans with the common p.Asp424His allele. In vitro functional validation confirmed that p.Thr459Met induces severe protein misfolding and intracellular retention, impairing enzyme secretion. Biotin supplementation triggered a documented and favorable therapeutic improvement, establishing this borderline enzymatic background as an actionable metabolic vulnerability unmasked by chronic gastrointestinal stressors. This study underscores the critical value of functional genomic characterization over static enzymatic biomarkers to identify highly treatable metabolic components within heterogeneous clinical landscapes.
Two forms--a priority test request form and a telephone results form--provide improved communication between the physician and the emergency laboratory of the Clinical Biochemistry Department. The priority test request form contains a list of available tests and it allows the physician to tell the laboratory exactly when emergency test results are required. The telephone results form ensures that the physician will receive a report, by telephone, of a test result although it may not be an urgent test. This allows a greater control of work flow, both routine and emergency, through the laboratory.
The biochemistry of phosphorus is outlined. As this element appears to have no redox reactions in biological systems phosphorus is always handled as phosphate and, as all phosphate compounds are thermodynamically unstable in water, phosphate uptake and incorporation are associated with energy consumption. The subsequent use of phosphate in metabolism and synthesis is illustrated by metabolic pathways and DNA (RNA) polymerizations, respectively. The importance and unique chemical significance of phosphorus in biology cannot be overestimated.
A complex stimulation regimen (visual, auditory, and somesthetic-kinesthetic with forced movements, 30 times for 30 min each within 14 days) increased significantly the amplitudes of visual cortical evoked potentials (EPs) in adult rats if applied during the second postnatal fortnight. The EP increase after stimulation during the first 14 days after birth was not significant. Visual stimulation alone was compared with complex stimulation (visual plus forced movements) during the 2nd postnatal fortnight. More specific local changes in the visual cortex were revealed in brain biochemistry (lower DNA concentration, more RNA and protein per cell) and cortical electrogenesis (enhanced visual EPs) after visual stimulation alone, whereas complex stimulation induced more diffuse changes and rather profoundly influenced higher nervous functions (viz., memory retrieval - improved 24-h). Involvement of both specific and nonspecific mechanisms in the aftereffects of early stimulation is indicated.
The renin-angiotensin system has an important role in maintaining elevated blood pressure levels in certain forms of experimental and human hypertension. Renin, an enzyme produced by the juxtaglomerular cells of the kidney, acts on a protein substrate found in the alpha 2-globulin fraction of the plasma to produce a decapeptide, angiotensin I. This decapeptide is not directly pressor, but on passage through the pulmonary circulation is converted to an octapeptide, angiotensin II, a very potent pressor substance which acts by causing constriction of arteriolar smooth muscle. In addition to its direct action which increases blood pressure, angiotensin II acts on the adrenal cortex to cause the release of the sodium-retaining hormone aldosterone. Recent evidence suggests that this action may be mediated by the heptapeptide, angiotensin III. Both renin and its protein substrate exist in multiple forms and renin may also exist as a high molecular-weight "pro-hormone," although the physiologic significance of these forms is not clear. The elucidation of the biochemistry of the renin-angiotensin system has provided us with inhibitors which allow the system to be blocked effectively in vivo. Thus, angiotensin antagonists such as Sar 1, IIe 8-angiotensin II and converting enzyme inhibitors such as BPP 9a (SQ 20881) have proved useful in the study of experimental and human hypertension.
Intranasal irrigation of mice with 0.17 M ZnSO4 solution results in the immediate and total loss of the ability to find a buried food pellet. This anosmia persists for 6 weeks in at least 80% of the treated mice and for 4 months in half of the animals. This marked behavioral effect is matched by a long-term reduction of the levels of carnosine synthesis and transport in the primary olfactory pathway. These biochemical parameters are virtually undetectable at two weeks after treatment and even at one year after treatment do not exceed 5-10% of average control values. Light microscopic observations of tissues of the primary olfactory pathway at various times after treatment are consistent with these observations and indicate a substantial destruction of the olfactory epithelium with subsequent atrophy of the olfactory bulb. At very long intervals after treatment, some receptor regeneration is apparent with accompanying reinnervation of the olfactory bulb. Estimates from microscopy and biochemistry suggest that much less than 10% of the normal complement of functioning receptor cells is adequate to give apparently normal food-finding behavior.
Results of a survey of accuracy and precision of weighing in a sample of clinical biochemistry laboratories in the U.K. are reported. 101 laboratories each carried out eight weighings. 94% of weighings were subject to errors of not more than 1.7 mg at the 2 g level and not more than 1.0 mg at the 100 mg level. However, 9% of the laboratories produced results which were consistently subject to larger errors.
The biochemistry of zinc has come under intensive investigation at the molecular level during the past 20 years. More than 70 zinc metalloenzymes are now known, and they span a broad range of biologic activities. Substitution of zinc by cobalt, for example, serves to locate a paramagnetic probe at the active site of the enzyme which can then provide information regarding the coordination properties of the metal and the active site environment.
The presented paper describes the role of enzyme histochemistry in cell biological investigations. In the first chapter a general discussion has been given about enzyme histochemistry as a connecting link between biochemistry and morphology. The methods available for determination of enzymes in a particular cell or cell compartment have been reviewed. In this respect the characteristics of enzyme histochemistry have been discussed. Furthermore, attention has been paid to the possibilities and limitations of enzyme histochemistry. In chapter two a comparison has been made between histochemically judged and biochemically determined enzyme activities. Some fundamental differences between the biochemical and the histochemical approach in cell biological investigations are dealt with. To correlate histochemically and biochemically determined enzyme activities, a description has been given of the application of histochemical methods on isolated fractions and sucrose-ficoll gradients of these fractions. Several experimental results are described concerning the question whether a relation exists between histochemically and biochemically determined activities of respectively alkaline phosphatase, glucose-6-phosphatase, 5'-nucleotidase and 3ss-hydroxysteroid dehydrogenase. From these results the conclusion could be drawn that in general a good correlation exists between histochemically judged activity per volume (area X thickness) and biochemically determined activity per gram tissue. In chapter three the role of enzymes as markers of cellular particles and as parameters of metabolic pathways is described. Histochemical methods are available for most marker enzymes. Only activities of key enzymes can be regarded as parameters of metabolic pathways. The distribution in sucrose-ficoll gradients of enzymes, regarded as markers of mitochondria, lysosomes, endoplasmic reticulum and plasma membranes has been given. The changes occur ing under different experimental conditions for a number of marker enzymes in rat liver are described. Attention has been given to the contibution of enzyme histochemistry in the study of the heterogeneity of mitochondria, the dual localization of some (lysosomal) enzymes, the complexity of the microsomal fraction, the function of the Golgi apparatus and the heterogeneity and function of plasma membranes. Based on these results and on literature findings the possible role of some marker enzymes in cell metabolism has been discussed. In chapter four problems coherent with species and sex differences in enzyme activities are described. The interpretation of histochemical and biochemical results in view of these differences is discussed. Enzymes characteristic for a given cell type -3ss-hydroxysteroid dehydrogenase in steroid producing cells, ATP-ase in liver plasma membrane surrounding the bile canaliculi - do show less variations between species and sexes than enzymes not directly involved in specialized functions...
Actins and myosins similar to the major proteins of muscle are the major molecular components of intricate mechanochemical systems that perform numerous vital motility and structural functions in all eukaryotic cells. In this article, after a brief summary of the morphological distribution and ultrastructure of actin, myosin, and interrelated proteins of nonmuscle cells, our present knowledge of their biochemistry is critically appraised from the perspective that understanding complex cellular processes depends ultimately on the identification, purification, and biochemical characterization of the proteins involved. Although few conclusions are reached, possible molecular mechanisms for cellular regulation of actin polymerization, filament association, actomyosin ATPase activity, and mechanochemical coupling are discussed and a number of potentially fruitful directions for further research are suggested. These include comparative biochemical investigations and the study of the interaction of heterologous proteins, but particular emphasis is given to the need for quantitative studies at the molecular level of motility proteins purified from a single cellular source.
Sequential evaluations were made of the morphology and biochemistry of trigeminal nerves from control and ethylnitrosourea (ENU)-exposed rats from 1 day to 6 months of age. Distinct increases in cellularity were evident as early as 20 days after exposure to ENU. Corresponding increases in N-acetyl-beta-glucosaminidase and beta-glucuronidase were detected at the same time. Transplantation studies were performed with grossly normal trigeminal nerves from 32-, 63-, and 91-day-old control and ENU-exposed rats. One of eight nerves from the 32-day-old ENU-exposed donors developed into neurinomas at the site of transplantation. No tumors developed from nerves of controls. These results indicate that the early increases in cellularity and acid hydrolase activities represent neoplastic rather than preneoplastic changes.
In the past two decades, biochemistry and molecular biology have demonstrated the existence of potentially exploitable biochemical differences between etiologic agents of disease and their hosts. Known differences between organism and host with respect to metabolism and polymer structure point to the detailed characterization of key proteins as the focus for the development of potential inhibitors. In the last decade, the methodology of the isolation, characterization, and inactivation of proteins and enzymes has been advanced. The present scientific and technological base suggests that new efforts toward the development of selective chemotherapeutic agents for infections caused by bacteria, viruses, protozoa, and higher eukaryotes should exploit the known differences in proteins or other specific biopolymers serving crucial structural or metabolic roles in the economy of the parasite.
The analytical goals inferred desirable by a group of clinicians for the imprecisions of a wide range of analytes have been studied by survey. The goals required have not in general become more stringent in the past decade and are not as demanding as those promulgated by laboratory professionals. Clinical biochemistry laboratories can now attain analytical imprecisions which satisfy the general demands of clinicians except for analyses of calcium and of low levels of glucose. The lack of published data on analytical goals does not allow wide comparison of criteria for performance standards with the results of this study.