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  <head>
    <title>087-03 Cofactors, biochemical regulation, pathway control, and molecular measurement</title>
    <ownerName>Integrated Medical Foundations</ownerName>
  </head>
  <body>
    <outline text="Cofactors, regulation, pathway control, and measurement">
      <outline text="Vitamin-derived cofactors">
        <outline text="Deficiency impairs enzymes sharing a task"/>
        <outline text="Excess adds little once enzymes saturate">
          <outline text="Stored fat-soluble vitamins can be toxic"/>
        </outline>
        <outline text="Status depends on absorption through clearance"/>
      </outline>
      <outline text="B vitamins in energy metabolism">
        <outline text="Thiamine pyrophosphate">
          <outline text="Oxidative decarboxylation, transketolase"/>
          <outline text="Brain and heart; lactic acidosis"/>
        </outline>
        <outline text="Riboflavin forms flavins">
          <outline text="Yellow urine mainly reflects excretion"/>
        </outline>
        <outline text="Niacin forms NAD and NADP">
          <outline text="NAD catabolic, NADP biosynthetic"/>
          <outline text="Skin, gut, nervous system"/>
        </outline>
        <outline text="Pantothenate: coenzyme A and thioesters"/>
        <outline text="Pyridoxal phosphate and amino-group transfer">
          <outline text="Neuropathy, seizures, sideroblastic anaemia"/>
        </outline>
      </outline>
      <outline text="Carriers of carbon and one-carbon units">
        <outline text="Biotin carries activated carbon dioxide">
          <outline text="Avidin binding, immunoassay interference"/>
        </outline>
        <outline text="Folate carries one-carbon units"/>
        <outline text="B12: methionine synthase and mutase">
          <outline text="Folate trap causes megaloblastic change"/>
          <outline text="Folate fixes anaemia, not nerve damage"/>
        </outline>
      </outline>
      <outline text="Other vitamins and metals">
        <outline text="Vitamin C: hydroxylases and non-haem iron"/>
        <outline text="Vitamin K: gamma-carboxylation, warfarin"/>
        <outline text="Vitamins A and D act via nuclear receptors"/>
        <outline text="Magnesium, zinc, iron, copper, selenium, others"/>
        <outline text="Free transition metals drive harmful redox"/>
      </outline>
      <outline text="Mechanisms of regulation">
        <outline text="Substrate availability sets flux">
          <outline text="Saturating in-vitro assays can miss defects"/>
        </outline>
        <outline text="Allosteric effectors report cell state">
          <outline text="Feedback inhibition of committed step"/>
          <outline text="Feed-forward activation"/>
          <outline text="Reciprocal regulation prevents waste"/>
        </outline>
        <outline text="Covalent modification by kinases, phosphatases">
          <outline text="Phosphorylation has no universal meaning"/>
        </outline>
        <outline text="Proteolysis: activation and removal">
          <outline text="Synthesis and degradation set abundance"/>
        </outline>
      </outline>
      <outline text="Compartments, hormones, and control">
        <outline text="Compartments separate competing pathways">
          <outline text="Cytosolic and mitochondrial NAD pools"/>
        </outline>
        <outline text="Insulin stores; glucagon, catecholamines mobilise"/>
        <outline text="Longer-term hormones change capacity"/>
        <outline text="Metabolic control is distributed">
          <outline text="Slowest step not automatically rate-limiting"/>
          <outline text="Control shifts with feeding, exercise, disease"/>
        </outline>
        <outline text="Energy charge and redox ratios">
          <outline text="Hard to infer from plasma"/>
        </outline>
      </outline>
      <outline text="Assay principles">
        <outline text="Direct measurement or coupled inference"/>
        <outline text="Spectrophotometry and Beer-Lambert relation"/>
        <outline text="Mass spectrometry is highly specific"/>
        <outline text="Immunoassays: competitive or sandwich">
          <outline text="Cross-reaction, heterophiles, hook, biotin"/>
          <outline text="Precise yet systematically wrong"/>
        </outline>
        <outline text="Accuracy versus precision"/>
        <outline text="Detection limits versus clinical sensitivity"/>
        <outline text="Calibration and traceability"/>
      </outline>
      <outline text="Interpreting results">
        <outline text="Pre-analytical variation exceeds instrument error">
          <outline text="Haemolysis raises potassium, lactate dehydrogenase"/>
          <outline text="Ongoing metabolism consumes glucose"/>
        </outline>
        <outline text="Reference intervals are not treatment thresholds">
          <outline text="Healthy people fall outside by chance"/>
        </outline>
        <outline text="Dynamic tests probe regulation">
          <outline text="Normal baseline, abnormal response"/>
        </outline>
        <outline text="Omics reveal patterns and hypotheses">
          <outline text="Multiple testing, batch effects, validation"/>
        </outline>
        <outline text="Specify reaction, compartment, time, assay"/>
      </outline>
    </outline>
  </body>
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